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

[Bobby B]

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.

Those reading are Key in troubleshooting your issues. I bet the head is way hotter near the passenger side rear two cylinders. This is where the crud usually gets lodged. Upper/ lower rad hoses shouldn't be more than a 10-15 degree differential.  You'll find it.....
                                                                        Bobby

[39LaSalleDriver]

For those following my adventure, here is the latest. As it turns out, I had to have the generator rebuilt. The guy said that it looked to him like the belt had been tightened too much and caused the armature to rub against the coils. I had hoped it was just the bearings, but hard lesson learned I guess.    So much for the thought that the belt was too loose and causing overheating.

As an interesting side note, they tried to sell me a new voltage regulator and claimed my old one was shot. Told them I didn't need the $130 one they were trying to sell me as I have a spare NOS one. As he handed me my old voltage regulator, he points to the battery terminal and asks "what's this?" I told him it was a voltage regulator fuse...makes me a bit dubious of their "expertise". Turns out, the fuse was indeed blown. Replaced it and the regulator is fine.

Reinstalled generator (keeping the belt a bit sloppier than I would have thought prudent) and everything is back to running fine as far as that goes. Drove it around town on a 90 degree day for a couple of hours, both on highway and city streets in modest traffic. No indication of it overheating at all...Stayed pretty well pegged at the halfway mark (right around 135 degrees). So I don't know...for now I guess I'll just keep an eye on it, and perhaps this winter I'll pull the radiator and have it gone over before I take it on any more serious long hauls.

I also took the time to go ahead and do a compression test with the following results:

Engine Temp          Approx 135 degrees

Cylinder          Dry          Wet (used 3 squirts of oil)

1                     55           70

3                     80           85

5                     65           70

7                     80           90

2                     78           80

4                     80           85

6                     85           89

8                     80           80   

I can't say there's any big surprises to me there, being as I know nothing about the history of whats been done to this engine. Looks to me like I could use a ring job, and probably have the valves ground while I'm at it. Particularly on cylinders 1 and 5. Otherwise, it looks pretty consistent to me. Any other thoughts out there of what I can take from these numbers?   

[bcroe]

I know little of your system, but fuses do not survive well in
a car environment.  That is one reason I prefer to use fusible
links under the hood, they also are much less likely to blow in
case of a mild, non dangerous, short duration overload.  Do
not know when they came into use, maybe mid 70s. 
good luck,
Bruce Roe

[KenZ]

Your overall compression is somewhat low with concern being to the 1 & 5 cylinders.  That being said if it runs OK I would just drive it until you can do the rebuild. Your overheating issue has turned into running too cool by my way of thinking, especially at 90 degrees ambient.  Believe most thermostats on flatheads were supposed to be 180 degrees and that's probably where Cadillac designed the engine run.  There are probably different degree thermostats out there and a lot of people have removed or disconnected pending the year of the flathead.  Is the 135 degree verified by the temp gun?  Do you have the thermostat disconnected?  If so, are the radiator vanes wired open?  The half way mark on my 1936 is aprox 170-180 degrees verified by using a temp gun.  The gauge and sensor are different from your 1939.  Guess the good news is you are not overheating.  I am sure others will share some thoughts...……  Happy Motoring, Ken                         

[Bobby B]

Looks to me like I could use a ring job, and probably have the valves ground while I'm at it. Particularly on cylinders 1 and 5.

That's equivalent to a "rebuild" with a Flathead. Drive it until it breaks, then dive in. Rebuilding a Flathead basically involves doing it all, since it's all in "The Block". Good Luck and Keep Us Posted!
                                                     Bobby

[39LaSalleDriver]

I know little of your system, but fuses do not survive well in
a car environment.  That is one reason I prefer to use fusible
links under the hood, they also are much less likely to blow in
case of a mild, non dangerous, short duration overload.  Do
not know when they came into use, maybe mid 70s. 
good luck,
Bruce Roe

I think we're talking about a different type of fuse here. Do a search for "voltage regulator fuse" on this forum. They are a quite robust metal and ceramic system, plus they are period appropriate.

Is the 135 degree verified by the temp gun?  Do you have the thermostat disconnected?  If so, are the radiator vanes wired open?  The half way mark on my 1936 is aprox 170-180 degrees verified by using a temp gun. 

A couple of months ago I charted my temps by checking the gauge and immediately noting temps at various points on the engine so I could get an idea of what they correlated to (see chart below). Unless something has radically changed, at the halfway mark on my gauge, the average across all of the cylinders is 135 degrees. Of course it may well be different on other folks' engine. I don't hit 170-180 until it is just beyond 3/4 (maybe at 7/8ths) or so up the gauge.  Thermostat is disconnected and louvers are wired open solidly.

That's equivalent to a "rebuild" with a Flathead. Drive it until it breaks, then dive in. Rebuilding a Flathead basically involves doing it all, since it's all in "The Block". Good Luck and Keep Us Posted!
                                                     Bobby

Thanks Bobby, that's pretty much my philosophy as well. I don't feel I'm lacking for hp or anything, always starts fine, and doesn't make any untoward noises other than the slight lifter tick, so for now I'm going to leave well enough alone as far as all that goes. I'd still like to get a handle on the overheating business (IF it's still happening). Will just have to wait until it happens again and see what can be done at that point. For right now, it runs great. Of course wait until I get out in the sticks somewhere cruising down a back road... 

[las39]

For those following my adventure, here is the latest. As it turns out, I had to have the generator rebuilt. The guy said that it looked to him like the belt had been tightened too much and caused the armature to rub against the coils. I had hoped it was just the bearings, but hard lesson learned I guess.    So much for the thought that the belt was too loose and causing overheating.

How does one tighten belt that much? With a crowbar between valve valley cover and gen?
I haven't figured how to tighten generator on mine without scratching or destroying something.

Also fan pulley belt tightening and how notch works is still a mystery to me 

[39LaSalleDriver]

How does one tighten belt that much? With a crowbar between valve valley cover and gen?
I haven't figured how to tighten generator on mine without scratching or destroying something.

Also fan pulley belt tightening and how notch works is still a mystery to me 

Here is an old photo of my generator when I first got the car. I don't know if this is the best way or even a good way but yes, I used the hook end of a crowbar. I inserted it underneath the generator from the direction of the red arrow and wedge it against the block as best I can. It can be tricky as there's not a good stable surface there so it's kind of a hope and pray, preferably two person operation. One to wedge while the other tightens the bolts. It can be done solo if you pre-tighten the bolts enough, but hardly precision. I too have found scratches to be inevitable.

I have also had some luck using an old hatchet handle and inserting the eye portion (minus the head) underneath the generator from the direction of the blue arrow. Just carefully wedging it in to not hit the oil line and hoping it takes up enough tension. If my recent rebuild experience is any indicator, this might be the superior method as I never over tightened it before. Plus, it doesn't scratch anything.

I'm sure there has to be a better way and would certainly entertain other methods.

As for the fan pulley, you've got me there. I too am mystified by that as I haven't seen any info on how it's done. I presume that you have to carefully get a wrench in between the fan and radiator and remove the blades first. All the while hoping you don't mess up and bang into the radiator fins. After that I assume you can loosen the adjusting bolt and let it all slide down. Now how you get it all tightened back up with the proper tension? I have no idea. Perhaps some of the older hands could provide some insight?

[bcroe]

I tend to take about an 18 inch angle iron, and make something on
one end that fits where needed to apply tension.  The same tool got
modified on the other end for holding/turning a crank.  Bruce Roe

[las39]

Hatchet handle, crowbar, angle iron 
I'm sure there is an "official" way to tighten them. I also would like to hear from the experienced.

[harry s]

     The idea is to not scratch the paint not the amount of leverage when tightening the belts. There should be at least 1/2" deflection in the properly tensioned belt. neither the generator or fan have any resistance to speak of but do have bearings that are sensitive to too much pressure. I remember when alternators first came on the scene there were instances of non charging due to belt slippage thus requiring more tension.
     Maybe I missed it somewhere in previous comments but the overheating issue  was not definitely resolved. I don't think it was related to the electrical system but don't have any ideas other than those already mentioned. I agree on the compression figures. Yeah a little weak and two cylinders beyond the 10% variance but not a problem. Keep on driving and  deal with at your convenience. Keep us posted.      Harry
       

[bcroe]

     The idea is to not scratch the paint not the amount of leverage
when tightening the belts.    Harry     

Right, a custom tool will allow rubber pads or whatever to protect
the paint.  There is no paint on these parts on my cars.  Bruce Roe

[39LaSalleDriver]

     The idea is to not scratch the paint not the amount of leverage when tightening the belts. There should be at least 1/2" deflection in the properly tensioned belt. neither the generator or fan have any resistance to speak of but do have bearings that are sensitive to too much pressure. I remember when alternators first came on the scene there were instances of non charging due to belt slippage thus requiring more tension.
     Maybe I missed it somewhere in previous comments but the overheating issue  was not definitely resolved. I don't think it was related to the electrical system but don't have any ideas other than those already mentioned. I agree on the compression figures. Yeah a little weak and two cylinders beyond the 10% variance but not a problem. Keep on driving and  deal with at your convenience. Keep us posted.      Harry
     

Thanks Harry. Honestly I'd prefer 1/2" deflection. The day before my generator died completely I put on a new belt in hopes of curing my overheating issue. At that time I adjusted it to have about 3/4" of play, but ultimately, even that may have been too tight. Keep in mind, that right then I was fishing for solutions to stop the overheating and didn't even realize my generator was in jeopardy. It is entirely possible it may have been going out for 2-3 weeks before I realized there was a problem and it finally crapped out. As I have it adjusted right now, there is just enough tension to keep it from squealing and falling off the pulleys.

By the time I got home the water was so muddied from me trying to find solutions that I've just had to sit back and let things settle out to see what happens. Now I can methodically go through things and find out what happened and how to fix it. It was certainly an odd coincidence, but I too now suspect the generator and overheating issues are/were unrelated. When you're several hundred miles from home, the mental gymnastics you go through to try and find answers don't always make sense, but you're willing to latch onto anything. 

[LaSalle5019]

My 1968 Tempest had an overheating problem years ago.  Tried everything and couldn't figure it out.  Eventually found that many of the fins on the radiator cross tubes were no longer secured to the tubes. I'm not sure if it was a quality defect or what.  It only had about 60k miles and body was in great shape so I doubt it was corrosion. They looked fine but you could grab them and move them back and forth.  Re-core solved a problem that took a long time and several parts to diagnose.  Something you could easily check.
Scott

[Jeff Maltby 4194]

I think we're talking about a different type of fuse here. Do a search for "voltage regulator fuse" on this forum. They are a quite robust metal and ceramic system, plus they are period appropriate.


https://www.ebay.com/itm/NEW-VOLTAGE-REGULATOR-FUSE-FOR-ALL-VEHICLES-WITH-20-29-AMP-REGULATORS-6-12-VOLT-/113616226958

[Bob Schuman]

Jon,
Several posts ago you wrote you will not disturb the head bolts. The flatheads often are found to have crud buildup in the water jackets of the block, especially toward the rear of the engine. Cadillac put a flushing procedure in a 1947 Serviceman Bulletin that can do wonders if crud in the block is the overheating cause. It does involve removing one head bolt at a time, starting at the lower rear left head bolt, and flushing while injecting compressed air to dislodge the crud. If your overheating recurs, that may need to be what you do, and it is a really messy job.
If your overheating recurs and nothing else cures it, block flushing may be the answer. I can post a copy of the Cadillac Serviceman procedure if necessary.
Before ever trying to remove any of the head bolts,  they should be smacked squarely on the head with a big hammer to hopefully help dislodge any scale or rust, and lessen the chance of breaking a bolt.

[39LaSalleDriver]

Jon,
Several posts ago you wrote you will not disturb the head bolts. The flatheads often are found to have crud buildup in the water jackets of the block, especially toward the rear of the engine. Cadillac put a flushing procedure in a 1947 Serviceman Bulletin that can do wonders if crud in the block is the overheating cause. It does involve removing one head bolt at a time, starting at the lower rear left head bolt, and flushing while injecting compressed air to dislodge the crud. If your overheating recurs, that may need to be what you do, and it is a really messy job.
If your overheating recurs and nothing else cures it, block flushing may be the answer. I can post a copy of the Cadillac Serviceman procedure if necessary.
Before ever trying to remove any of the head bolts,  they should be smacked squarely on the head with a big hammer to hopefully help dislodge any scale or rust, and lessen the chance of breaking a bolt.

Bob,

Thanks for the commentary. I am very familiar with that procedure and have all the Serviceman Bulletins. Given my circumstances both financially and feasibility, that solution would be my second to last resort. The last being a complete engine tear down and rebuild. By no means am I afraid of the time involved or mess it may cause doing the Serviceman procedure IF I knew it wouldn't lead to additional trouble. Now it may well be I could get away with it and have no problems. However, an equal (if not greater) possibility is that I could shear off one or more of those bolts and then I'm back to a complete tear down. That really isn't an option for me at this point and I'm not much of a gambler. So if that is indeed the problem, I'll just have to live with it for now.

What I did do back in May was to pop out the drivers firewall core plug and shot up in there with a pressure washer, wire, screwdriver, and fingers. Honestly, I was disappointed that I didn't find much up in there. In fact, I was quite surprised how clean it was. Granted, it could be a false sense of security that I didn't find much; but combining that with the fact that I am getting fairly consistent digital temperature readings at multiple points around all cylinders at temperature suggests to me that buildup in the block is not my issue (157 being the lowest, 166 the highest). While I will admit my assessment could be wrong, I would think that I would have cool spots in areas of buildup and that it would overheat rather consistently regardless of circumstances and I'm just not seeing that. The inconsistency of WHEN it overheats or doesn't overheat is maddening. A block so plugged up would overheat to some level all the time (like any time I drive it for more than say 20 min.) would it not?

Again, for right now it seems I'm not having any more overheating issues, but then again, I haven't run it hard for a three plus hour stretch since this all happened either. Therefore I don't really know if it's still doing it or not. Should I discover that it is, I'm going to start by pulling the radiator and having a pro take a look at it.

[Bob Schuman]

Jon,
I agree completely with your analysis and approach to the overheating, if it even still exists. I just wanted you to be aware of the Cadillac procedure, which you already knew about.
Good luck.

[bill_boos]

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
                                               

Rather old topic, but would appreciate your opinion re  " as close as it can be without scraping?"
My '47 Cadillac is overheating and I just removed the water pump. Impeller seems tight on the shaft and blades are about 1/8" from body. Is this adequate for water flow?

Radiator is reading around 200 and heads 280 to 350 depending on location. Just ran water from each top hose through engine to water pump outlet and got about 30 seconds of rusty water from each side before it began running clear.  This may not be enough to clear passages. Will refill with coolant to see if any improvement. Thermostat temporarily removed. Spark was retarded causing hard start and carb backfiring . Advanced about 1/2" without timing light --- starts in about 2 seconds and no hesitation/backfire when accelerating. Still no pinging.

Any thoughts appreciated. Bill

[DaveZ]

Back to what Bob said about the Cadillac procedure. Just running water through the block will not clean the lower areas of the water jacket where stuff has built up. We took the head bolts out and I made a special copper tubing adaptor for my power washer to go all the way down to the bottom with a split orifice on the end. Realize that what you think is the bottom may not be the bottom because of the build up of crud. It will feel hard. When it is clean you will definitely feel and hear the difference when dropping a metal rod down the holes:-)