Was: 160 degree thermostat for a 1968 Now: cooling off a 1968 DeVille

[cadillacmike68]

Scot, where do you hide your temp gauge, and how is it hooked up (where is the sender located? I really do need to get mi gauge "calibrated. I'll do that when I change the pump (or earlier). We'll just sit there with the IR gun and get actual temp readings at 1/4, 3/8, 1/2, 5/8, and 3/4 (that's as high as i will let it get!). That should shed some light on this.

I'm going to call those FlowKooler folks tomorrow. I have a new ACDelco pump, and it has a similar, if not identical impeller, but it costs half what the FlowKooler one costs ($56 vs $119).  I do like the robert shaw stats though, so I'm definitely getting one one of those.

Chris, I put water wetter in mine too, and do not notice any advantage. Maybe for hot racing applications with no thermostat, but not our cars, i guess.

If the water wetter is really lowering the temps, the stat will just partially close to allow the coolant temp to get hotter. It will still eventually settle on what the stat is calibrated for.

[Scot Minesinger]

Mike,

Not hidden, removable.  Unplug, one bolt and gone - good for shows.  There is a tach in the glove box.  The gauge is way better than the IR gun.  The sensor is under compressor and I lose the warning light - who cares, plus still have the hot block light.

[TJ Hopland]

I used to think who cares about the stock lights too but then I had to re rebuild my engine after the oil pump failed and I always wondered what if I caught it sooner?   Now I have gauges and the lights.  I figure it can't hurt to have both. 

[Scot Minesinger]

On my gauge cluster still have the oil pressure light, but not temp light.  There is a hot block light, and that I still have. 

The hot temp light is not a great value, it basically informs you when there is an extreme situation only.  This is true because when you shut car off on super hot day with a/c running and come back to it in 20 minutes, the temp is past 230'F which means that the warning light probably does not illuminate until say 250'F or so.

The oil press light is probably the same, a real low press situation indicative of a leak.

The gauges help you prevent a future problem.  My volt gauge is the best because it saved me on a bad regulator and a bad alternator - two times it saved me from a possible break down.

[TJ Hopland]

It is nice that the Cads have the metal temp lights.    If I am really feeling like not paying attention my gauge system has a very loud alarm that can be enabled.  I turned it on once, no way you could miss it.  I think its intended for RV's where you may not be near the gauges.

My water light seems to start to glow in the 230 range.   Sometimes I will see it slightly glow just before a hot restart.  Its not the original sender, its one I picked out of a catalog.  I don't remember what the set point was supposed to be, I was not expecting 230 but I am happy with that. 

If you can find an old school parts store that still has older books you can just page through various sensors and pretty much pick the set points you want.   Some industrial engines have oil pressure switches in the teens vs the car stuff that is more like 5.

[chrisntam]

Here's my gauge set up.

["Cadillac Kid" Greg Surfas 15364]

Chris,
I'm going to make a wild guess that you don't spend a lot of time looking at the tach.
Greg Surfas

[chrisntam]

Only after I get done sending a text!!



It's nice look down and see how many revs it is.  I no longer need "shift points", as I have become an old man!  It's more for monitoring...........

chris.

[cadillacmike68]

Those are both nice setups.

[Scot Minesinger]

My tach is in glove box.  Use it to set idle, set timing, and monitor occasionally.  It is also useful impressing my friends who wonder what rpms it requires to reach 70mph.

[cadillacmike68]

Well, I got the FlowKooler pump and RobertShaw stat in.

The Impeller looks like it will move more liquid than even the new ACDelco unit, which also has a round impeller but with shallower vanes and only 6 vanes compared to 10 on the FlowKooler pump. The Delco unt will by my road trip spare. The stat is a unique construction. I'll try to remember to take a couple of pics tomorrow in the daylight before installing it.

We'll try to get it flushed out and installed tomorrow. I'm replacing the upper and lower radiator hoses as well and any suspect looking heater lines. The rad itself is fine as is the heater core. I also have a 1960-70 overflow tank installed. That has really helped the past few years, by preventing coolant loss to the ground.

[cadillacmike68]

Well, the FlowKooler Water Pump and Robert Shaw Thermostat were both installed and while driving back that night all was fine. The next day in blistering 100 plus heat, during a 17 mile traffic jam, it went to 3/4 and a bit over (but didn't boil) and stayed there until I got to my house. It was like a 1,000 car procession, every light required waiting for 2 or 3 cycles to get through, and the light ahead was already red before I got through the one i was on. That was really rough.

When I finally got home, I drove it for about 10 more miles at 55-65 MPH around the development and it cooled right back down to 1/4. An hour later I drew off some coolant to look at the radiator and it looks like the coolant is flowing nicely through the radiator. It also idled for over 30 minutes without going over the 1/4 mark.

We checked the temps across the radiator and there is a steady progression from about 195 on the upper hose to 180, 170, 160, 150, 140, etc until just before the return tank and then Wham! 185 degrees F. WTF??

The transmission cooler is in that tank, and sure enough when the car has been driven, those lines get quite hot - and they are taking away all the cooling done across the radiator.  Normal THM400 operating temp is 170, but these lines were 180-185. Hmmmmmm...

The radiator cap was also suspect so I changed it. Not sure what that will do, since it has not boiled over at all, and I have had a 1969-70 coolant recovery tank installed since 2005.

Went to Ocala (approx 75 mi each way) on Sunday,  it warmed up to 1/4 (approx 180 deg) and only rose after it got very hot outside to about 3/8 way. Going home at night it never went over 1/4.

Had the transmission fluid flushed and filter changed. It seemes to run a little cooler. Gauge was slightly Below 1/4 while driving, but still crept to 3/8 while stopped for any length of time.

I'm looking at two last items. First timing; Ineed to make sure base timing is 5 deg BTDC with no vacuum input. Second I need to make sure that the Distributor Vacuum Switch is working. Of course that switch isn't supposed to shift vacuum unless coolant gets to 230F, and that's almost pegged on the gauge. This is the 3 port vacuum switch that is near the distributor (4 ports on 69 & later) and supplies either carburetor or manifold vacuum to the distributor. Again, it is only supposed to switch to MT when the coolant temp gets to 230F, so maybe it hasn't gotten that far yet?? Who knows.

Maybe the car isn't operating out of design parameters. The owner of the shop that flushed the lines, said the car didn't want to overheat, and  the extreme traffic is an abnormality. It's just very unnerving with all the money spent on the overhaul, i don't want to burn any bearings.

If the above doesn't help further, then I'm looking at an aux transmission cooler and an engine oil cooler mounted up front. These should both take a load off the regular cooling system.

I've looked at Hayden and Derale. Does anyone have any experience or opinion on either of these brands? They seem similar and both have light, medium and heavy duty applications.

[Scot Minesinger]

Mike,

The oil cooler is a great idea.  So is the independent trans cooler.  If possible do not make those in series with air flow thru radiator.  If I lived in South FL or TX, probably would do this.  Also you can do a fuel cooler too.  One of the lesser discussed purposes of oil is to cool engine too.

Have not heard from you much about the fan that draws air across a/c cond and radiator.  The fan from commercial chassis is superior air flow than the one for standard chassis.  Try and get one of those.  I did that on my 1970, 5 blade standard (no clutch), 7 blade commercial.  Also, do you have the fan shroud and radiator sealed well so that air drawn by fan cannot by pass radiator?  That rubber sheet piece on the bottom of radiator really helps cooling on a 1970 Cadillac.

Yes check the timing!  That can make a huge difference.  You can tell also a little if your car shifts hard between 1-2 and 2-3, timing may be too retarded.

Keep in mind that the 0.030 inches over bores do tend to run hotter than factory (mine is bored thirty over too, so it is a 478)

My car never gets tested like you described because if it is sunny and 100'F my top is down and a/c is off.  If it rains (usually does at the end of a sunny 100'F day) top goes up and a/c on, so less strain on cooling system. 

I got stuck in a 3 hour sit and idle never go more than 5mph trip home form GN 2013 in sunny afternoon, 95'F in NJ.  Top was down, enjoyed talking with neighboring stranded car occupants.  Temp never crossed 215'F, but a/c was off.

Enjoy your Cadillac,

Scot

["Cadillac Kid" Greg Surfas 15364]

Scott said "Temp never crossed 215'F, but a/c was off.".

With the Air conditioning on, on a ,say 95 degree day, in slow moving traffic, the air going through the condenser will exit the condenser and enter the radiator at somewhere around 130 degrees.  If you are driving at say 65 MPH, there is enough air flow to lower both the condensing temperature and the resulting air flow to the radiator temperature.

The Flow-Kooler pump increases the water flow at low speeds, up to (I believe) 2500 RPM, and the 7 Bladed All steel factory HD Cooling fan increases the low speed airflow.  With these two devices and a correctly running engine and non clogged radiator, a 472/500 motor will stay well within the design temperature the engineers designed it for.  The motors do not stay at an exact temperature but of course vary as the load and conditions change.  That was clearly understood and devices were incorporated to change timing settings when required.  Chasing a numerical "ghost" was the reason that I removed the water temperature gauge from my Eldo decades ago.  If there is an actual problem the "water" light will alert me.  In spite of my car b eing subjected to some of the most demanding conditions from 110 degree phoenix traffic to constant 100+ MPH across the CA desert, the only time the water light stayed lit (it often came on for a moment when the car was re started after a hot weather "heat soak" was when I blew a hot water heating valve.  These cars were meant to be driven by people that had absolutely no knowledge or interest in how they worked mechanically, so ALL systems and devices were designed to be indestructible as long as all fluids, belts and hoses were correct.
Mike,
chasing the temperature gauge can drive you nuts without gaining a thing.  If you have the "water" light installed and operating it will warn you in plenty of time if there is something wrong.
Greg Surfas

[Scot Minesinger]

Greg has got to be right and a point we forget about, my Grandmother (she enjoyed a 64, 67 and 73 Caddy SDV) turned on the climate control and drove her Cadillacs everywhere without regard for temp gauge setting.  Never has my caddy run rough or noticed any difference no matter what temp gauge reads.  My light never even glowed before it was disconnected on a heat oak after running on a hot day and restarting after 20 minutes. 

Sometimes when people ride with me and it is 95'F, sunny and top down they complain at the stop light and I turn the a/c on for them, it helps a little.  It does drive the temp gauge up about 5'F after ten minutes at idle.  Conversely, I put manifold vacuum on power servo to drive heater on as an experiment during 90'F day just to see what it will do and it lowers temp gauge about 8'-10'F.  Provide the car is above 180'F on temp gauge to as hot a it ever has gotten, it runs the same when in proper tune.

[35-709]

"Mike,
chasing the temperature gauge can drive you nuts without gaining a thing.  If you have the "water" light installed and operating it will warn you in plenty of time if there is something wrong.
Greg Surfas"

Hear!  Hear!  Been there done that. 

[cadillacmike68]

Mike,
The oil cooler is a great idea.  So is the independent trans cooler.  If possible do not make those in series with air flow thru radiator.  If I lived in South FL or TX, probably would do this.  Also you can do a fuel cooler too.  One of the lesser discussed purposes of oil is to cool engine too.

The mfs all prefer that you run the trans cooler in series with the in-radiator cooler, but they say the tank cooler can be bypassed (they recommend  the next larger size cooler though). I have this under serious consideration and will use either Hayden or Derale, and will use their top tier lines. No cheap-a$$ tube & fin coolers for me. The engine oil cooler being a new addition could only help.

Have not heard from you much about the fan that draws air across a/c cond and radiator.  The fan from commercial chassis is superior air flow than the one for standard chassis.  Try and get one of those.  I did that on my 1970, 5 blade standard (no clutch), 7 blade commercial.  Also, do you have the fan shroud and radiator sealed well so that air drawn by fan cannot by pass radiator?  That rubber sheet piece on the bottom of radiator really helps cooling on a 1970 Cadillac.

I believe my shroud is pretty much airtight, and I have all the splash guards in place (new ones) including the all important one under the radiator.  The fan is a 7 blade with clutch as specified for All AC equipped cars for 1968. There is very good fan draw across the condenser and radiator and good cooling from 195 to 140 or so across the radiator at idle. I also have a 1970 7 blade no-clutch fan, that I might consider, but I think that won't be needed.

Yes check the timing!  That can make a huge difference.  You can tell also a little if your car shifts hard between 1-2 and 2-3, timing may be too retarded. 

I'll check the timing, the Distributor Vacuum switch, and the idle speed up & fast idle this week. I need to find my spring kit from the Crane Cams adjustable vacuum advance kit to reduce the high RPM mechanical advance (needed for the crappy modern fuel). The transmission has always been fine. I don't think it got over 230 from reading the manual.

Keep in mind that the 0.030 inches over bores do tend to run hotter than factory (mine is bored thirty over too, so it is a 478).

Yes, this whole thing might be just the result of the boring out for the overhaul. It did seem to run a little cooler yesterday, but I was in a downpour. I need to get out on another hot afternoon.

My car never gets tested like you described because if it is sunny and 100'F my top is down and a/c is off.  If it rains (usually does at the end of a sunny 100'F day) top goes up and a/c on, so less strain on cooling system. 

I got stuck in a 3 hour sit and idle never go more than 5mph trip home form GN 2013 in sunny afternoon, 95'F in NJ.  Top was down, enjoyed talking with neighboring stranded car occupants.  Temp never crossed 215'F, but a/c was off.
Enjoy your Cadillac,
Scot

The sun here is oppressive, and I had the top up & AC on last week in that jam. 

The Flow-Kooler pump increases the water flow at low speeds, up to (I believe) 2500 RPM, and the 7 Bladed All steel factory HD Cooling fan increases the low speed airflow.  With these two devices and a correctly running engine and non clogged radiator, a 472/500 motor will stay well within the design temperature the engineers designed it for...

...If there is an actual problem the "water" light will alert me...  ...ALL systems and devices were designed to be indestructible as long as all fluids, belts and hoses were correct.

Mike,
chasing the temperature gauge can drive you nuts without gaining a thing.  If you have the "water" light installed and operating it will warn you in plenty of time if there is something wrong.
Greg Surfas

I'm sort of getting to be in agreement.

I don't have the water temp light, the 68s still had the gauge, but from the owners manual, maybe I'm getting too concerned over what is considered normal function. I do have the engine metal temp buzzer and that does work. It activated once in 2005, fortunately i was just stopping the car anyway.

1968 Owners Manual P 10:

"Normally, The gauge pointer will more gradually from the extreme left when the engine is cold to approximately the one-quarter mark. Do not be alarmed if the the pointer registers above the center range in heavy traffic or on long drives during warm weather. The pressure controlled radiator overflow will normally prevent coolant losses up to 259 deg F"

This is exactly what it does - it just seems to be too often for me, but it is very hot here in the summer (and on sunny days in the winter too!). I never lost coolant and have the 69-70 closed system in use. Even with the older RC27 cap, it never blew out the overflow tank.

"The temperature gauge can sometimes register "H" (Hot) under severe operating conditions. However, this is not necessarily cause for alarm unless the the red warning light (the engine metal temp light) is on, and the warning buzzer sounds.

Hmmmm...

The warning buzzer only sounded once, and that was back in 2005, before I had the 4 core radiator put in. The buzzer goes off, and the temp gauge pegs the H. Even in that long traffic jam, while the gauge did indeed get pretty close to the H, the buzzer never went off, and it cooled right back down once I got to a 2-3 mile open road.

I pretty much replaced or serviced the entire cooling system by now. No leaks, radiator flow is fine, fan & clutch are good, new condenser with no blocked / dented fins, good cooling progression across the radiator from upper hose to the other side, new cap & hoses, and now a cleaned out transmission with fresh oil. No vacuum leaks that we can detect (I went through that the past 6 months with the climate control).

I do have two things working against me:

First, the block is bored .030. This makes a difference, but how much???
Second I do have a  mild Comp Cams cam in the car. This is not supposed to affect idle quality, but it might be, and it might be dropping carb vacuum at idle a little thus retarding timing a little. This as I have come to find out can cause the engine to run hotter, so I'll check that when I re-set the timing next week.

I just scored a couple NOS GM ported vacuum switches (in case mine had gone bad), so that'll be covered,

["Cadillac Kid" Greg Surfas 15364]

Mike,
It seems you are satisfied with the car's performance.  Can we close this topic?
Greg Surfas

[cadillacmike68]

If a moderator wants to lock it, fine.

I'd really be satisfied if the gauge never went past 1/4, but that's not going to be the case. I just want to be sure I'm not damaging bearings. I spun a bearing in my old 1970 way back. I didn't know what happened, and in a couple minutes it broke the connecting rod. You don't ever want that to happen. A couple years prior to that, I blew out a freeze plug on the interstate at night, and that's where I probably caused the bearing damage.

I don't want that happening with this car.

After I verify timing is correct and the Distributor Vacuum switch & idle speed up are working correctly, and (IF) I put the coolers in, I'll post those results. There won't be any more postings from me until I make further changes to the car.

[Scot Minesinger]

Mike,

The reason the trans cooler independent of the radiator install instructions is to be in series with radiator is that it does not have a fan more than likely and relies on the car radiator fan for air flow.  This is the same almost as having it integral to the radiator in that ultimately the engine coolant also cools the trans as is the case now.  The trans cooler I probably intended for radiators without a trans cooler. 

You can buy an inexpensive 12V fan from Summit racing and attach it to the trans cooler with a stat powered by ignition on only power source.  Then it will not need to be in series with radiator fan.  This will accomplish your goal of not having the engine coolant absorb the trans heat too.  Make sure you have a high capacity trans cooler, because by your account the trans was a significant source of heat.

BTW same with oil cooler, independent fan too.  The oil does not get cooled otherwise, so anything you add will be a help, contrary to trans were you need to at least equal what the radiator capacity is.

Are you one of those convertible top up guys when it is not raining and gets a little hot?  When I was a kid my Dad would only lower the top on 1970 Oldsmobile convertible when it was 72'F, sunny and no humidity and the car did not have a/c!  I thought he used bad judgment operating the car.  We set out sometime to not repeat our parent's perceived errors when we were kids.  If it is over 50'F and not raining the top goes down.  In 2009GN at LV rented a Mustang convertible and the top was down at mid day 105'F and I loved it.  Just messing around here, but when it is hot and sunny, the solution to your engine running hot issue is drop the top and turn off the a/c.  If a ran my car in 100'F + temps with a/c on in stop and go traffic for hours, I might have started this thread.