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Flathead overheating -- could it be the under-seat heaters???

Started by Justin Norwood, May 25, 2018, 07:50:31 AM

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Justin Norwood

Friends,
My '47 Flathead has a major overheating issue that I need your help with diagnosing. The symptom is that after even a relatively short drive (e.g. 20-25 mins) at relatively mild/warm weather (e.g. 85 degrees), when I stop the car the fluid in the radiator is boiling over and it vents through the overflow onto the ground. It has been doing this ever since a cosmetic restoration that I did earlier this year, which makes me think that perhaps something either broke or wasn't reassembled properly during the restoration.

So this week I decided to get my hands dirty myself. I replaced the old 180* thermostat with a new 160* thermo, even though I tested the old one and it was working just fine. Then I also replaced the water pump and the radiator. Lastly, I inspected the block for corrosion and passage blockage -- but it looked fine. I drove the car last night, and it overheated again!

In my mind, I am running out of places to check for issues. The only thing I can think of is if there is something to the order/direction in which the hoses that run from the block to the under-seat heaters...and if those were reattached incorrectly, could it be causing an issue with the normal flow of cooling fluid???

I guess my questions are three-fold:
1) Aside from my heater hose theory, is there any other place I should be looking for an issue?
2) Do you think my theory around the heater hoses could be correct?
3) If the answer to #2 is "Yes" -- can anyone advise with a quick diagram (even a back of the napkin sketch) of how the under-seat heater hoses are supposed to be connected? I can't seem to find that info in my shop manual.

Thanks in advance!
-Justin
1947 Cadillac Series 62 Sedan

Hilarius

Hilmar Schneider #26898
1930-162, "353", 4D-SDN-7P
1940-7567, 2D-CCP-2/4P
1948-7519X, 4D-SDN-5P
1952-6019X, 4D-SDN-5P
1973 Mercedes 107R, 2D-CCP-2P
2015 Cadillac SRX, 4D-SDN-5P

Steve Passmore

This type of situation has been discussed a few times. What temperature does it reach?  When you say it puts out water when you stop, do you fill it back up to the top again?  These cars never want to be filled up to the top in the rad. All the cars I have owned would push out a quantity of water and find the correct level which is hard to see in the rad. 
Is it a faulty radiator cap?
Next is a radiator with insufficient or blocked cores. When you say you changed the radiator, was it for a newly built one? or just another old one lying around?
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Bill Ingler #7799

Justin: Just because the radiator looses coolant after you stop, does not mean you have an over heating problem. As Steve wrote, the level of the coolant is very important. Coolant expands as it gets hot so fill the radiator with coolant to the bottom of the top tank, just slightly above the top of the core. Now go drive the car and see if you are still pushing fluid out the overflow. If yes, there are several other possible areas that might be causing over heating.  Do you have the correct radiator cap? RC-7 is the correct cap. It is a 9lb cap. Here are some diagrams which explain the hook up of the cooling/heating system in you car.
Bill

Justin Norwood

Bill, (and everyone)
THANK YOU SO MUCH! In the "Explanation of the Cadillac Automatic Heating System" was the exact diagram that I needed! Furthermore, the associated text reads as follows:
"Reversed connections...to the underseat heaters will affect the temperature distribution at the body."

That's putting it mildly!  ;D

I am 99.9% sure that this is my issue. I will confirm shortly (after the car cools) and revert back to this message.

To answer everyone else's questions:
-Hilmar: Thanks for that thread. I previously saw that and knew that I was correctly connected in the engine bay. My question was more about the connections at the heaters.
-Steve: I went with a brand new, factory spec, remanufactured radiator that came with a radiator cap. And, yeah...I noticed a month back what you are  saying about these radiators not wanting to be completely full...but what happens when my car "overheats" is another matter entirely. It's like it takes a MASSIVE PEE all over the ground in a rather dramatic fashion (not a drip). [Please excuse my colorful description]
1947 Cadillac Series 62 Sedan

V63

The heating system would be a ‘no effect’ unless it’s leaking fluid or pressure.

Steve Passmore

. It's like it takes a MASSIVE PEE all over the ground in a rather dramatic fashion (not a drip). [Please excuse my colorful description]
[/quote]

Justin, that's exactly what happens when the radiator is too full, and it only happens when you come to a stop. It can put a 1/2 gallon out in one go!
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

35-709

If it is truly overheating, there is a Cadillac Service Bulletin (that I don't have) that has been posted on these forums in the past concerning flathead overheating, hopefully someone can find it (or has it) and can repost it here again.  Number one though, a visual inspection is not and will not be sufficient to determine that your cooling passages are clear or plugged with rust and crud.  Basically, the service bulletin (from memory alone) calls for pulling the water pump and then beginning at the rear, remove one head bolt at a time and using a long tube on a blow gun to flush the crud out.  This is only a short version of the procedure --- a friend with a '41 was amazed at the rust and junk that came out and it cured his overheating problems.   

1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

35-709

Again, assuming the engine is truly overheating ---
Looking around I found this thread from 4 years ago, it seems to cover just about everything from soup to nuts.
http://forums.cadillaclasalleclub.org/index.php?topic=131057.40

Only thing that hasn't been mentioned yet on this thread is the possibility of a collapsing lower radiator hose --- probably because it hasn't been determined yet that it is overheating or just being overfilled.  After it pees out don't add water back.  Check the water level and drive it and see if the water level stays the same when it cools off again.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Steve Rinaldo

Having fought this battle before. I suggest you check the easy things first.
1. Make sure the radiator hoses are not collapsing.
2. Make sure the ignition timing is advancing properly. This is a main cause of this issue.
3. As stated what is the Coolant temp. In the summer 200 is not odd the pressure cap adds about 2 degrees per pound to the boiling point.
4. If the problem occurs at speed it might be an air flow problem. take a look for missing baffles, fan shrouds etc.
Good luck Steve


autoluke

TIMING...TIMING...TIMING

After chasing what I believed was a radiator/coolant problem , the culprit was incorrect ignition timing.


Also suggest that you invest in a radiant temp gun, and check water temp at various locations.
Phil Lukens

C Gorgas

Isn't it amazing how we do not see the easier to diagnose problems first. I had a similar problem and was trailered home twice before I woke up. Chet

Hilarius

My 39-6127 engine was overheating in the summer for years, just as described above.
Everything mentioned in this thread was done to no effect.
Then someone, I think it was Steve P., came along with the proposal to check the ignition in a way as to advance it until pinging would occur.
I advanced it bit by bit until pinging started and then retarded until pinging could not be forced, anymore, even with the trans in high at low speed and full throttle.
The ignition marking on the belt pulley was about 1/2" off by that time.
The engine runs fine and has never overheated ever since.
Don't know why the "ign" marking isn't correct, anymore, I attributed it to the use of modern gasoline, as the pulley could hardly have moved on the crankshaft.
Hilmar.

Hilmar Schneider #26898
1930-162, "353", 4D-SDN-7P
1940-7567, 2D-CCP-2/4P
1948-7519X, 4D-SDN-5P
1952-6019X, 4D-SDN-5P
1973 Mercedes 107R, 2D-CCP-2P
2015 Cadillac SRX, 4D-SDN-5P

Justin Norwood

Fascinating stuff in this thread. I will certainly keep my eye on all of these potential issues -- especially ignition timing. Thank you all.

A couple of responses:
1) The car was definitely overheating when I started this thread. After I would stop driving, not only would the radiator PEE out a MASSIVE amount of fluid, the remaining fluid in the radiator would LOUDLY boil for 10-20 minutes after shutting off the engine. I have video evidence if ya'll need it. :)
2) the fan wasn't the issue as I had put in a 2500 CFM electric fan a while back. that thing pushes some SERIOUS air!

In terms of what I found:
I am not entirely sure if I found the resolution or not, but I did in fact have the two hoses on the passenger side heater hooked up in reverse order. I fixed that, and put on a new lower radiator hose, and after driving the car for an hour, it did not overheat -- which is notable because it was overheating after a 20 minute drive before. For now I am crossing my fingers hoping that all is well...even if it doesn't make sense to me at the moment.
1947 Cadillac Series 62 Sedan

Justin Norwood

Probably no surprise to anyone on this thread, but...my overheating issue is back.  >:(

I am going to check/play with the timing next... I'll report back.

-Justin
1947 Cadillac Series 62 Sedan

Rich Iannelli

Hi Justin,
My 37 Lasslle Coupe was overheating like yours. I followed the advice of the members
And started to loosen and lube the head bolts. It took me a week of lube and slow turning of the head bolts. I removed the water pump and use a rod for insulation
Hanging and my pressure washer. The amount of scale flowing out of the water pump opening was amazing. I installed a temperature gauge with numbers and before the “fix” I was at 230 degrees in traffic. Today I am at 130 for the first 20 minutes then levels out at 185 to 190. When I gas up, I use Sta-bil marine ethanol additive and a lead additive. I also installed a pusher fan which goes on at 190 degrees. (For those 90 degree days)

Good luck and don’t give up. I enjoy my car very much now that it doesn’t overheat.

Rich
Aim at nothing and you will hit nothing

Justin Norwood

For posterity's sake (for anyone encountering flathead overheating issues down the road)...

Rich's advice was spot on. I was afraid to do the engine block flush because my head bolts looked original (aka 70+ years old) and were rusty...even from the outside, much less the parts that were sitting in the block! I thought that I was running a high risk of breaking off a head bolt in the block.

After trying everything else to no avail (electric fan, new thermostat, new water pump, new radiator, adjusting the timing, correcting the coolant flow direction on the heaters, etc), I was still getting water temps over 225* (aka it was boiling over) whenever I would take a drive over 15 mins long in the florida summer heat. Furthermore, the right side was running a LOT hotter than the left side (> 20+ degrees).

So finally I worked up the courage and I had the block flushed.

We did just like Rich said, taking a week of lubing the head bolts with PB Blaster. They ended up coming off perfectly! We flushed the block and the amount of crud that came out was astounding!!! After that I tested it again with an infrared thermometer and it wasn't overheating anymore, but I still noticed that the right side was running a little hotter than the left side -- likely due to the proximity of the exhaust to the right side radiator source hose. So we also wrapped the right/top side of the header in exhaust wrap...and now everything is PERFECT! (see pic attached) We also painted the heads and installed new zinc plated head bolts while we were at it.

I am now driving around in florida with temps in the low 90s (with a heat index > 100*), and the water temp leaving the radiator is right around 175* (which is what my thermo is spec'd at), and the temps entering the radiator are in the 185* - 200* range. No more overheating.

P.S. I am running a Flex-a-lite FLX-118 with 2,500 cfm output hooked up to a FLX-31174 electric fan controller (activated by a radiator probe and my AC switch)...so your results may vary if you're running a stock 4-blade fan.
1947 Cadillac Series 62 Sedan

Bobby B

Quote from: revvies on September 17, 2018, 06:41:22 PM
We flushed the block and the amount of crud that came out was astounding!!!

Nobody would believe the cement like crud packed between the #6-#8 cylinders. You have to see it to believe it  :o.  Even more Fun picking it out.......
                                                                                                                                         Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Steve Passmore

Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

DaveZ

I made an attachment to my power washer out of copper tubing. Soldered the end closed and took a fine saw blade and cut two slots at the very bottom opposite each other.  Took out the rear bottom head bolts drain plugs and water pump. The pressure from the power washer really breaks up the 5 pds of crude sitting in the block.  Even if you are going to rebuild the engine and have it tanked you still have to do it because whatever they do doesn't break up the crud. After you are done I recommend putting the gani filters on the rad hosed so what ever crap remains doesn't end up in the radiator. Check them after running because they may fill up fast and block flow. I had to clean them out a few times.
Best of luck,
One who learned the hard way:-)
Regards,
David Zitzmann
1932 345B