Pre-war (up to 1942) 1939 LaSalle - Overheating, Generator Failure

[39LaSalleDriver]

Where to begin? Just got back from a long run with my 39, and have encountered a series of problems that have me puzzled.

To begin with, I have the typical overheating problems even after doing EVERYTHING that can be done short of pulling the head bolts or rebuilding the engine. Up until my adventures a couple of months ago, everything had been reasonably fine as could be, or at least predictable. Therefore we can skip the wire the shutters open, hose collapse, advance the timing, etc., etc., etc. solutions. That has all been done and this situation is somewhat different. I'll bypass some of the leadup variables which I don't think relevant.

I put in my rebuilt for the second time water pump from the Flying Dutchman (not his fault, it was my mistake) about two and a half weeks ago. Flushed the engine again just to be sure. Trip started out okay, but engine ran a bit hotter than I would have expected. Gauge was reading about 7/8ths, or just shy of HOT (verified true with digital thermometer). Not happy with that, but I could live with it given circumstances.

The problem became that the overheating was inconsistent, it would run cooler at times when I expected it would overheat, and hotter at times when it should have been cool. For example, been running close to hot, stop to get gas, pull out on interstate (no hard starting), tool along for a couple of miles at around 60 mph and it shoots up to HOT. Pull over on side of road and shut it down, let it cool off for 10-15 minutes, start it up (no hard start again), pull out and gauge rides at about 3/4. Then I hit construction work...slow down to about 25-30 mph for about 4-5 miles and the gauge drops down to 1/2 to 5/8ths. Past experience has shown me that that thing should have been burning up in the construction zone on a fairly warm to hot day!

Something else was happening too that I thought odd at the time, but didn't hit me until much later. When the engine would get hot, the ammeter would peg all the way to charge and just stay there. When it was running cooler, it would stay in it's normal range, spiking once in a while when it would kick in charging as per normal and then back down to just above the center mark. Oil pressure gauge was also giving me odd low readings at times that may or may not be connected.

After arriving at destination, I thought maybe the belt was a bit loose on the water pump. I don't get any squealing, and I try to keep it at around 3/4" of play. Tightened that a bit, but still get the same result. Don't know how old the belt is (it came with car), but maybe it's day has come. Replace the belt. Also suspect perhaps an air bubble in the block could be the culprit. Let it sit idling for an hour with the radiator cap off. Gauge eventually goes up to halfway mark and never moves beyond. So far, so good. Go to drive car around town and start to get a bit of belt chirp (expected that) but also a whining noise from the generator as the rpms go up. I have to drive about 30 miles on back roads to my destination. For the first five or so miles (at 45 mph) it starts overheating again and ammeter pegs as well. Had to make a quick stop, and then out of nowhere, all the gauges go back to normal and I complete the rest of the trip with no issues. Next morning, starts up fine, except I'm not really hearing the whining noise, and the ammeter is below the center on the discharge side. Based on headlights not fluxuating and so forth, I'm pretty sure the generator is no longer working.

So...I'm pretty sure the bearings are shot and that's why the generator is acting up (at least I hope it's that simple). Does it sound possible to anyone else that perhaps the generator bearings have been the problem all along? Is it possible the generator has been causing a drag on the belt which has slowed down the ability of the engine to cool? If so, wouldn't the ammeter peg to the discharge side rather than to the charge side? Does any of this make sense? Has anyone else encountered a situation like this?

[Bob Schuman]

Are you sure the ammeter is connected correctly? The car was originally positive ground, and if converted to negative ground as many have been, the ammeter will read backwards unless its wire connections were reversed. Your generator theory of excessive load making the belt slip looks plausible also. Keep us informed what you find-this is a puzzler.

[39LaSalleDriver]

Are you sure the ammeter is connected correctly? The car was originally positive ground, and if converted to negative ground as many have been, the ammeter will read backwards unless its wire connections were reversed. Your generator theory of excessive load making the belt slip looks plausible also. Keep us informed what you find-this is a puzzler.

Should be correct. Been running it for a year and a half with no problems, i.e. charges when appropriate, discharges when headlights are on and so forth.

[35-709]

For the amount of driving Jon said he did, if the belt were slipping that much to allow the car to overheat, I can't imagine you wouldn't smell hot/smoking rubber from that belt.  If the generator put a big load on the engine without the belt slipping you would certainly feel it in the engine's performance, would you not?

[KenZ]

I would just start by getting the generator fixed and just see what happens after you know the generator is good.  If the generator was locking up, you would hear it and the belt would smoke or get very hot.  If my memory is correct you have had overheating problems prior to this event with dialog on the forum.  Did you ever do a compression check on the cylinders? If you have not pulled the head bolts then its hard to be sure you have no crud build up in the block.  Yes, I realize the risk of breaking the bolts but sometimes you have to do what you have to do.  You probably don't have to pull all of them, just the areas where the crud builds up. Is the coolant level staying full (you are not losing any coolant)?  Good Luck!

[39LaSalleDriver]

For the amount of driving Jon said he did, if the belt were slipping that much to allow the car to overheat, I can't imagine you wouldn't smell hot/smoking rubber from that belt.  If the generator put a big load on the engine without the belt slipping you would certainly feel it in the engine's performance, would you not?

Some of my thoughts exactly, yet here I sit.    Trust me, I've had a lot of time the last few days noodling through what is going on and figured I'd wing it out there to get some fresh perspective. A real puzzler to be sure. At no point have I had any squealing belts, nor smell of hot rubber. Only a whining noise from the generator as I increase rpms.

Here's the way I see it...I have two separate issues going on that may or may not be connected. One is the generator was going kaput and finally did so. The question then becomes what, if any effect that had on the engine overheating? I personally can't really see it, but the correlation between the temperature gauge running at normal, and then pegging at hot at the same time the ammeter runs normal and then pegs to full charge cannot be ignored.

The other issue is the engine overheating. It's not losing water so we can take that off the table. Other than "normal" overheating issues like everyone else has ever had, it never behaved this way until the beginning of June when I had a water pump go bad from a blown seal. The water pump issue has been resolved and my pump rebuilt by the Flying Dutchman then reinstalled about 2 1/2 weeks ago. Unless the job he did was not adequate (which I seriously doubt), I don't see the water pump being the issue, but ultimately can't rule that out yet. I personally have never pulled the radiator or block and had them flushed out. Admittedly, that could be a long term problem, but "long term" is the key phrase. Unless one rust flake too many just happened to tip the engine into catastrophic overheating on an inconsistent basis (runs great for an hour in 92 degree weather, then overheats, then cools off and runs great at idle, then overheats within three minutes from cold the next morning driving down the street at 35 mph in 70 degree weather) I cannot seriously consider that to be the problem. A gradual over time problem keeping the engine cooled at any temperature I can see, but not one day it's running great, then the next it starts acting like this (which is exactly what happened).

Is the temperature gauge faulty? Possibly, but I don't think so. When hot, I was shooting temps on the heads in the 200 degree range consistently around every cylinder.

So here are the components involved that all interact and what I have done:

Cooling System (Keep in mind, I don't know of the car is overheating now or not. I MAY have cured that right before the generator problem became apparent. It could have been the old belt was slipping or an air pocket in the block that I finally worked out. I just don't know yet.)

Water Pump - Newly rebuilt and installed. If other steps don't cure my situation, will pull it again...
Water Pump Pulley - Reused old one which I had suspected may be involved in my problems a couple of months ago due to the woodruff key sitting too deep in a Kantor pump I bought in an emergency. Won't rule out this slipping on impeller, but I don't think this is the situation now.
Drive Belt - Replaced with a new one.
Radiator - Has respectable flow from what I can tell at idle. Has never been boiled out to my knowledge. If problem persists, will pull it and have it looked at.
Block - Have no solid proof it has ever removed from car and rebuilt/cleaned. But because it was painted that nasty seafoam green/blue, I suspect it has been out and rebuilt at some point. Digital thermometer readings show consistent temps at all cylinders (within 5-10 degrees) which suggests to me that it is surprisingly clean, though I could be wrong. I have run two batches of Thermocure through the system and pulled the core plug at drivers firewall. Found minimal crud. Inserted pressure washer to blast loose anything it could reach. Head bolts WILL NOT be removed any time soon. Call me a chicken, but I can't afford the gamble of one breaking, as I am in no financial position to be able to have the engine rebuilt or replaced; nor do I have a storage space that I can allow the car to sit for months or years waiting for the day I can afford it. Just ain't happening...If a plugged block is the problem, I'll just have to live with it as is for now and satisfy myself with driving it around the neighborhood a couple of times a week, but realistically, I don't think the block is the problem. Ran chemical block test last month and found no evidence of exhaust in cooling system, nor have I found coolant in the oil, or water vapor in the exhaust. It may have had an air pocket in there which caused the overheating to begin with, but this past weekend I have tried to eliminate that as a possibility, and indeed, may have cured the overheating by doing so.
Hoses - All new, with coil spring installed in lower hose.

Electrical System

Generator - Has failed. Pulled it out today and will take it to a shop tomorrow to have it looked at. Hopefully it's just the bearings that are shot.
Voltage Regulator - Don't know if this is a problem, but pulled it to have the shop test it to be sure.
Ammeter - No indication that it is inaccurate as far as it goes.
Temperature Gauge - No indication that is inaccurate as far as it goes.
Timing - Advanced to about 10 degrees TDC.

So this is where I am right now. I'll be taking my generator and voltage regulator in for testing/repair as necessary. When I get them reinstalled, I'll see if it's still acting up like it has lately. If not, problem solved. If it is, I'll start all over again with flushing the system, pulling the water pump and making sure that's all in order. If it's still acting up, then I'll move on to pulling the radiator and having it boiled out. If I still haven't gotten it fixed by then, I guess I'll be driving around the neighborhood a lot...

[Daryl Chesterman]

Jon I don't know anything about your particular car, but I find it interesting, the correlation between temperature gauge spiking up/down and the Ammeter spiking up/down.  Assuming that the temperature gauge is electric, would not extra voltage, or amperage, make the temperature gauge give a false/higher reading, due to the resistance staying the same(assuming that the engine temperature is actually not changing)?  The spiking ammeter could be due to a direct  short causing the voltage regulator to see an increased load and thus calling for the generator to charge at a higher output, and thus the whining.  This could be verified by a separate gauge or handheld meter.  I think that it would be interesting to see if the voltage spikes up and down with the temperature gauge.  My bet is that there is a short somewhere in the system that is causing all of the problems!  When you get the generator and voltage regulator checked out, you might ask the technician about this possibility.  Generators were not made to run at max output for any length of time, as this would cause them to seriously overheat to the point of melting the solder where the armature windings are connected to the commutator.

I am assuming that the oil pressure gauge is mechanical, not electrical, and its variable reading is an entirely different/separate problem.

Daryl Chesterman

[Bobby B]

Jon,
Hi. Everyone of these radiators that I've seen has been clogged to some degree. Forget about "Hot Tanking" it, or checking the flow while in the tank. I had a clogged one showing 70% flow, so figure that out. They all wind up full of junk. After it's done, run the Gano Filters on your upper hoses and sleep at night. I would Start with the radiator and go from there. I've had a few of these engines apart and the cement-like crud hovering around the back cylinders is no Myth, and has been discussed here and beaten to death. Your engine is no exception. If it wasn't torn down, tanked, picked out with coat hangers, snakes, trans picks, (and other sharp instruments), and tanked again, this is most likely the source of your problem. I spent 2 full days cleaning out my block after it was tanked before machining. Brand new water pump or not, the water isn't reaching around your cylinders properly. If it isn't any of the above, I had the same random spiking problem and it turned out to be hairline cracks between the valve seats overhanging the cylinders, and of course, it was mysteriously in the rear passenger cylinders where all the crud was lodged. I wouldn't continue driving it if I were you, until you get to the bottom of it. You could be doing more damage. Good Luck!
                                                           Bobby

[DaveZ]

How long was the water pump off for and where was the car stored while the water pump was off?  If it the car did not over heat before you took the pump off then something happened between the time you took it off and put one back on.  This may sound stupid, but I have found mice in the strangest places. If one of those little bstrd's got into the top of the radiator while the pump was off they could have brought crap in it. Around here you have to cover every hole:-( I currently have one trying to make a nest in my barbecue. Also you said you flushed the block at some point. When you did that did you pump the gano filters in the upper hoses? Anything you loosen will end up in the radiator which was already probably closing up form years of use.  Bobby is correct in boiling the rad. It is of no use. We sent ours to Maine and had a new cores put in both cars. I agree with you on there being two isolated issues between over heating and the electrical.
Best of luck!

[39LaSalleDriver]

Jon I don't know anything about your particular car, but I find it interesting, the correlation between temperature gauge spiking up/down and the Ammeter spiking up/down.  Assuming that the temperature gauge is electric, would not extra voltage, or amperage, make the temperature gauge give a false/higher reading, due to the resistance staying the same(assuming that the engine temperature is actually not changing)?  The spiking ammeter could be due to a direct  short causing the voltage regulator to see an increased load and thus calling for the generator to charge at a higher output, and thus the whining.  This could be verified by a separate gauge or handheld meter.  I think that it would be interesting to see if the voltage spikes up and down with the temperature gauge.  My bet is that there is a short somewhere in the system that is causing all of the problems!  When you get the generator and voltage regulator checked out, you might ask the technician about this possibility.  Generators were not made to run at max output for any length of time, as this would cause them to seriously overheat to the point of melting the solder where the armature windings are connected to the commutator.

I am assuming that the oil pressure gauge is mechanical, not electrical, and its variable reading is an entirely different/separate problem.

Daryl Chesterman

Interesting thoughts. I will definitely raise them when I get to the shop to have them check my parts out. I certainly can't discount the possibility of a short somewhere.

Jon,
Hi. Everyone of these radiators that I've seen has been clogged to some degree. Forget about "Hot Tanking" it, or checking the flow while in the tank. I had a clogged one showing 70% flow, so figure that out. They all wind up full of junk. After it's done, run the Gano Filters on your upper hoses and sleep at night. I would Start with the radiator and go from there. I've had a few of these engines apart and the cement-like crud hovering around the back cylinders is no Myth, and has been discussed here and beaten to death. Your engine is no exception. If it wasn't torn down, tanked, picked out with coat hangers, snakes, trans picks, (and other sharp instruments), and tanked again, this is most likely the source of your problem. I spent 2 full days cleaning out my block after it was tanked before machining. Brand new water pump or not, the water isn't reaching around your cylinders properly. If it isn't any of the above, I had the same random spiking problem and it turned out to be hairline cracks between the valve seats overhanging the cylinders, and of course, it was mysteriously in the rear passenger cylinders where all the crud was lodged. I wouldn't continue driving it if I were you, until you get to the bottom of it. You could be doing more damage. Good Luck!
                                                           Bobby

Thanks for your input. As indicated above, I think the first order of business is to get the generator and possibly voltage regulator issues situated before I do anything else. With those in good order, I can then properly analyze what is going on with the heat, that is, if it still is in fact overheating. I don't know for sure. I may have resolved that somewhat the other day right before I realized I had a problem with my generator. Maybe not.

But at this juncture I see no sense in immediately jumping from figuratively one day it runs fine and the next day I need to tear down the engine and replace the block. Smaller, less radical diagnostic steps are the order of the day for me right now until I can get a clearer picture of what's going on by addressing one potential failure point at a time. The fact is, it may well have cracks in the valve seats or have a completely clogged radiator and/or block. Or it may not. I just don't know, nobody does, but time will tell. My end goal here is to get it back to running as well as it did before all this mess started back in June. A mess that started not with a clogged radiator or block, or cracked valve seats. No, it started with a blown seal on my water pump.

Before that as far as could be told, everything was fine. It would overheat sitting in traffic too long. It would get hot in 90+ degree weather, but come back down with airflow. Things that I would expect with one of these engines and could live with. Figured I'd wing this all out there to see if anyone had had a similar circumstance vis a vis the overheating connected somehow to a generator output spike and how it all may be interconnected.

If I'm lucky, once the generator gets fixed, maybe my other issues will go away or have been resolved as well.

[39LaSalleDriver]

How long was the water pump off for and where was the car stored while the water pump was off? 

About as long as it took to take one off and install the other, so I don't think that would be a factor

Also you said you flushed the block at some point. When you did that did you pump the gano filters in the upper hoses? Anything you loosen will end up in the radiator which was already probably closing up form years of use.  Bobby is correct in boiling the rad. It is of no use. We sent ours to Maine and had a new cores put in both cars. I agree with you on there being two isolated issues between over heating and the electrical.
Best of luck!

No, I thought about Gano filters, but after reading around I ended up using a pair of pantyhose donated by my S/O instead. After running that for about a week, I honestly didn't pull much out. Maybe a teaspoon of rusty sludge with somewhat of a mudlike consistency.

If/when I get to the point of pulling the radiator, I'll probably run it over to a guy (old timer) who runs a radiator shop near me and see what he has to say. May well have to have it recored at which point I'll start looking at options. Thanks

[bcroe]

Just a couple comments.  I am pretty sure your generator problems
have nothing to do with overheating.  I run cars well past 200,000
miles, and the temp gauge eventually stops staying at the thermostat
open point.  Then I get the radiator recored, or a new one (probably
a better performer than the original) and the gauge behaves again. 

If that fails, you most likely have an engine problem such as described
above.  Pulling an engine is not a huge project, and even removing
heads does NOT in itself demand a rebuild.  good luck, Bruce Roe

[Bobby B]

Jon,
I didn't mean to scare you into tearing into your engine, which wasn't my point. Pulling the heads is simple enough, but would be the last resort after all options were exhausted. If the water pump was going bad and you replaced it, how long was the car running hot until the water pump finally went? Was it creeping up gradually over time until one day you noticed the temp was not within range? Do you have an infra-red gun so you can check temps at various spots around the engine, radiator, and hoses? I agree with Bruce regarding the Gen problem having nothing to do with your overheating issue. You can narrow this down pretty quickly as to what's causing this. I chased this problem for years, and like others, know that these Flatheads WILL run, even when crippled with problems. There's a reason why they were used in tanks during the war. I ran my car at 70 MPH on the Freeway, not knowing that it was running on 6 cylinders, and it really wasn't noticeable. They are robust engines......
                                                                                             Bobby

[39LaSalleDriver]

Jon,
I didn't mean to scare you into tearing into your engine, which wasn't my point. Pulling the heads is simple enough, but would be the last resort after all options were exhausted.

I imagine it scares me because I know that some day it will likely have to be done...just not today or any other day soon

If the water pump was going bad and you replaced it, how long was the car running hot until the water pump finally went? Was it creeping up gradually over time until one day you noticed the temp was not within range?

Bearing in mind, the first set of problems started on a trip I made back the first week of June. On that occasion I ran roughly 300 miles solid before noticing an overheating situation. That drive involved work zones and modest mountains (east Tennessee). It was then that I discovered that my water pump was leaking. Because of circumstances, I determined to push onward which I achieved by adding water every couple of hours. During this period it ran hotter than I like, but didn't reach the HOT mark. I was able to travel an additional 500 miles in this fashion. By now pump was making noise and I decided a new pump was going to be necessary. Got a replacement pump from Kanter which was only two hours away, (good thing we had a chase car to go pick it up) and installed it in the hotel parking lot the next day. After installing pump, fired it up and drove around block from hotel and the temperature gauge read HOT immediately. Since I knew the engine couldn't really be hot, I determined it must be an air pocket. Over the next day or so of driving only say 5-10 miles I would keep getting the same effect, pegged at HOT, but these were false readings (checked with digital thermometer). On Sunday started heading for home. Drove eight hours straight (nearly 500 miles) with no issues, temperature gauge read at about 3/4 mark. Then out of nowhere while taking exit ramp, gauge pegged to HOT (these definitely were not false readings). Pulled it over, shut it down and let it cool off until we could proceed to the hotel we were staying at. Next morning, drove around town a bit with no problems. Got out on highway and gauge started climbing. Pull over, stop for a while. Drive on, pegged hot within 5 miles. Pull over wait for an hour. Made it nearly 70 miles doing this and finally gave in and called AAA.

Got it home and I sent the old pump to Flying Dutchman (had been rebuilt by him a year before). When I got it back, I pulled the Kanter pump off and put my original one back on. Ran fine for a couple of weeks and then began this trip where I started having further problems.

So no, this wasn't a gradual situation. It literally started overnight with my trip a couple of months ago after replacing my leaking water pump. Before that time, I had had no unexpected or unusual overheating. I have no doubt that I'm still fighting whatever caused the overheating AFTER I put the Kanter pump on. I know it can be easy to blame the Kanter pump, but since it still behaves the same way after putting my original pump back on I don't think it's the pump itself that is the problem.

So you can see why I am so frustrated right now and grabbing at any theory. I just feel it has to be either an air pocket in the block, the belt, pulley, water pump, impeller shaft, or generator that is causing this to happen more or less overnight. A clogged radiator or block would have manifested itself long before this and in a gradual fashion I would think. But if I replace the other components and get no satisfaction, I will then have to turn my attention to more costly options like recoring the radiator, or ***gulp*** pulling the heads.

[z3skybolt]

USNtar,

I have followed your adventures and issues from the time that you began posting. As I have a 1940 LaSalle I've felt a bit of kinship.  It is regretful that you are having all these overheating issues.  Must be frustrating as hell. You have tried and acknowledged all the common fixes and concerns. None seem to have provided the solution.

My heart goes out to you.  I would listen very carefully to Bobby B. and his comments as he is very familiar with these engines and has experienced most of the significant issues with our flatheads. 

I don't feel that you should be afraid of pulling the heads. Even a broken bolt is not an insurmountable problem or very expensive. If your heads have been off in the past and they probably have.... then the bolts may be of little concern.  At least with the heads off you will get a better view of what is going on.

The irregular overheating may be from more than one cause but could be, as Bobby B. says.....gunk in your engine or cracks in the block.   About half of these old engines have cracks from past overheating. Those could cause irregular overheating issues as you have described.

I know that overheating is scary. My newly ($12,000.00+) overhauled engine overheated the day that I drove it home after the engine was reinstalled.  The radiator boiled over. The inoperative louvers had fully closed and caused the engine to overheat.  A couple hundred miles later one of the "freeze plugs" fell out while cruising. The engine dumped out the coolant, went to full hot and even dieseled when I shut her down. A sure sign of excessive overheating.  I was terrified that the block may have cracked. But 6,000 miles later there have been no indications of any issue with the engine.

Believe me I understand financial constraints. But don't hesitate to find the cause . I know that it is scary .....sort of like not having a PSA test for fear of the results. But in the long run.....better not to do further damage and then wait for the day when you are willing/able to make the necessary repairs.

In a few days my wife and I will leave for hiking/camping out west but will follow your progress upon return.

P.S.  I've had both the generator failure(squealing. stopped charging etc.) and water pump failure as you have experienced. In addition: voltage regulator failure,spark plug wire broken, distributor cap, rotor, points and condenser failure. None of which caused any overheating.

Best Wishes,

Bob R.

[KenZ]

USNtar,
Just a couple things to add.  You state that you have never lost any water when running the vehicle.  Do you ever hear any gurgling sounds from the radiator after shutting the engine down?  If its not gurgling and loosing coolant than it may not be overheating.  These old gauges are not always right on.  Also stated when shooting temps on the heads it is in the 200 degree range consistently around every cylinder.  200 degrees on the cylinder heads does not seem overly hot especially on a warm 80-90 degree day. Have you ever observed the radiator temp (top and lower)?   It could still be running hotter than it should and with the unknowns it would be piece of mind (at your convenience of course) to know your radiator and engine block are clean and free from blockage.  Driving the car will be more fun too!  One last thought …. is your radiator cap correct and functional?  My 1936 Cadillac runs on the hot side, at high speeds, with a new radiator and fresh engine but never vapor locks.  I don't really drive it much once it's over 90 degrees due to the Arizona heat.  Please keep us posted.  Thanks,  Ken               

[Bobby B]

Jon,
Are you 100% sure that the Impeller is not slipping once the engine comes up to temperature and the clearance between the impeller and the pump housing is as close as it can be without scraping? Ask me how I know  ........I always "tack" my impellers on after rebuilding. Pontiac 400's always run hot and an easy way to shave 5-10 degrees off your temp is to close up the gap between the pump impeller and the body. It does work. There's no need to spend money troubleshooting this problem.
                                                                                                                                   Bobby
                                                 

[39LaSalleDriver]

USNtar,

I have followed your adventures and issues from the time that you began posting. As I have a 1940 LaSalle I've felt a bit of kinship.  It is regretful that you are having all these overheating issues.  Must be frustrating as hell. You have tried and acknowledged all the common fixes and concerns. None seem to have provided the solution.

My heart goes out to you.  I would listen very carefully to Bobby B. and his comments as he is very familiar with these engines and has experienced most of the significant issues with our flatheads. 

I don't feel that you should be afraid of pulling the heads. Even a broken bolt is not an insurmountable problem or very expensive. If your heads have been off in the past and they probably have.... then the bolts may be of little concern.  At least with the heads off you will get a better view of what is going on.

The irregular overheating may be from more than one cause but could be, as Bobby B. says.....gunk in your engine or cracks in the block.   About half of these old engines have cracks from past overheating. Those could cause irregular overheating issues as you have described.

I know that overheating is scary. My newly ($12,000.00+) overhauled engine overheated the day that I drove it home after the engine was reinstalled.  The radiator boiled over. The inoperative louvers had fully closed and caused the engine to overheat.  A couple hundred miles later one of the "freeze plugs" fell out while cruising. The engine dumped out the coolant, went to full hot and even dieseled when I shut her down. A sure sign of excessive overheating.  I was terrified that the block may have cracked. But 6,000 miles later there have been no indications of any issue with the engine.

Believe me I understand financial constraints. But don't hesitate to find the cause . I know that it is scary .....sort of like not having a PSA test for fear of the results. But in the long run.....better not to do further damage and then wait for the day when you are willing/able to make the necessary repairs.

In a few days my wife and I will leave for hiking/camping out west but will follow your progress upon return.

P.S.  I've had both the generator failure(squealing. stopped charging etc.) and water pump failure as you have experienced. In addition: voltage regulator failure,spark plug wire broken, distributor cap, rotor, points and condenser failure. None of which caused any overheating.

Best Wishes,

Bob R.

Bob,

Thanks for the kind words. I definitely pay heed to everyone's advice here and give everything careful consideration. This is one of the things I most value from this forum is that so many before me have had about every imaginable problem under the sun that they encountered and hopefully resolved. On top of that, they have been willing to help out newer guys like me. I try not to wear everyone out with simplistic stuff like how to change spark plug wires, but sometimes I hit a brick wall and can't figure something out; or like this case, am fishing for angles and solutions that I may not have thought of. We'll see how it all goes.

USNtar,
Just a couple things to add.  You state that you have never lost any water when running the vehicle.  Do you ever hear any gurgling sounds from the radiator after shutting the engine down?  If its not gurgling and loosing coolant than it may not be overheating.  These old gauges are not always right on.

Not offhand.

Also stated when shooting temps on the heads it is in the 200 degree range consistently around every cylinder.  200 degrees on the cylinder heads does not seem overly hot especially on a warm 80-90 degree day.               

Perhaps not, but thus far my policy has been to get it to the side of the road and shut down the second I see the gauge peg to hot. Perhaps excessively paranoid, but I figure better safe than sorry.

Have you ever observed the radiator temp (top and lower)?   

I have, but I can't recall exactly what readings I've gotten (hard to remember some things when you're in a panic on the side of the interstate with trucks zipping by). I seem to recall it being slightly below the heads, perhaps 10-20 degrees lower.

USNtar,
One last thought …. is your radiator cap correct and functional?   

Yes. A 7 lb. RC-13 about a year old.

I don't really drive it much once it's over 90 degrees due to the Arizona heat.  Please keep us posted.  Thanks,  Ken               

I don't like to either. Not so much because of engine overheating, but that the cabin is rather unbearable in those temps.

Jon,
Are you 100% sure that the Impeller is not slipping once the engine comes up to temperature and the clearance between the impeller and the pump housing is as close as it can be without scraping? Ask me how I know  ........I always "tack" my impellers on after rebuilding. Pontiac 400's always run hot and an easy way to shave 5-10 degrees off your temp is to close up the gap between the pump impeller and the body. It does work. There's no need to spend money troubleshooting this problem.
                                                                                                                                   Bobby
                                                 

No, but it's definitely something that has crossed my mind. Not impossible, but I would find it unlikely that two separate water pumps would fail so quickly in such a fashion. Definitely something I will be looking into should this persist. I will also strongly be looking at the pulley itself and the possibility of it slipping on the impeller shaft. In analyzing all of this I have to ask myself, “what changed or stayed the same between my first signs of problems and now?” Water pump “A” ran great other than the blown seal, so I replaced it with water pump “B”. Water pump “B” ran great for 8 straight hours of interstate driving, and the engine began inexplicably overheating. Cause of failure, unknown. Had water pump “A” rebuilt for a second time to fix the blown seal and reinstalled it on car. Water pump “B” was boxed up and placed in trunk for emergency use. Now the possibility exists that water pump “A” is failing too, or is it? It could be fixed now, or it could be an air pocket. Another possibility is that the slot in the pulley has gotten buggered up and allowing it to slip on the impeller shaft. The two things shared by each of the water pumps is the belt (which I've since replaced) and the pulley. When I get my generator reinstalled and IF I discover there is still a problem with overheating, this is one thing I will be looking at for sure. I have another pulley to put on there should it come to that.

[Bobby B]

Jon,
Hi. My money's on the water pumps being OK. HIGHLY Unlikely that 2 water pumps are bad rendering the same results. Betting on a clogged radiator and/ or poor circulation around the cylinders. Do the temp gun thing before you start taking things apart. They are under $30.00 now and are relatively accurate enough to compare temps around your components. Good luck!
                                                                      Bobby

[39LaSalleDriver]

Jon,
Hi. My money's on the water pumps being OK. HIGHLY Unlikely that 2 water pumps are bad rendering the same results. Betting on a clogged radiator and/ or poor circulation around the cylinders. Do the temp gun thing before you start taking things apart. They are under $30.00 now and are relatively accurate enough to compare temps around your components. Good luck!
                                                                      Bobby

I agree, I just can't see the water pumps being the problem, but anything can happen. Definitely have a digital thermometer. Like American Express used to say, "don't leave home without it"

When I get my generator mounted back on I will definitely try to recreate the circumstances (only here around the house rather than a couple of hundred miles away) and shoot as well as notate the readings.