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346 overheating

Started by RonMorey, May 22, 2023, 06:35:29 PM

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RonMorey

Greetings all. Was going to take my 47 in for a roadworthy inspection after a frame off restoration. Foiled again. Now I have overheating. Any suggestions are greatly appreciated. My first question is to make sure I have the connections/flow  correct. The pump 5/8" output hose connects to the LH rad hose at the block. The LH cyl head output fitting, by the temp sensor, connects to the upper heater connection. The lower heater connection goes to the pump input at the lower rad hose. Is this correct?

The pump vane clearance is good. The thermostat is new and opens fully, closes smoothly. It is 170F and has the element towards the rad hoses not the radiator. The flow through the rad appears good. No air bubbles. The engine is freshly rebuilt. I have straightened the fan blades. They clear the rad by about 3/8". I have run to the end of possible cures. I can blow through the block, pump and heater easily. Any ideas before I lose even more gray hair?

Bill Ingler #7799

Ron: Have you had the radiator top tank off the radiator? I have had both a 41 as well as my 47 overheat. I had my local radiator shop remove the top tanks and both radiators showed over 50% plugged cooling tubes. Replaced the old core with new cores and no more overheating. Another thing that can add to an overheated engine is the front engine pan that sits across the frame and under the radiator. If your car does not have one then part of the air coming through the grill will pass under the radiator rather than through the radiator and over the engine which helps with cooling. I also have a 5 bladed fan from a 47-75 on my 47-62 convert which also helps with cooling.   Bill 

LaSalle5019

One way to gain about 30% better cooling capacity instantly is to ditch the glycol and run straight water with a good corrosion inhibitor, like No-Rosion.

https://www.no-rosion.com/productpage.htm

I do this in several of my pre-war cars to greatly increase margins for overheating. This is also a good solution while diagnosing issues as it's simple to clean up and won't ruin your paint if you get hot coolant all over.

Yes, glycol has a little higher boiling point but at 50/50 glycol and water you loose like 30% of the ability to transfer heat due to glycol's poorer thermal conductivity and specific heat characteristics.

The issue comes down to winter. I keep my stuff in a heated garage over the winter. You could always try it and switch out in the winter if you live in a colder climate.

On my 1939 LaSalle, I run about 25% glycol as I run it late in the season just before the snow flies and this will keep me safe to 10 deg F. I add No-Rosion to ensure no corrosion issues. Doing this I only lose about 10% heat transfer capacity. That car never gets too hot.

Other suggestions:
When the engine was rebuilt did you take the time to really flush the block out well?

As suggested above, the radiator could be partially blocked or missing shields.

I'm not sure of the correct heater hose routing for your car but as long as you don't short circuit the pump you should be good.




V63

Often a "new" engine will run hotter until it breaks in.

Try advancing your timing, running too far retard causes the temperature to go up dramatically.

If it starts to crank slower or you get pinging it's too far advanced for the fuel you are using.


James Landi

I have been greatly surprised by the amount of scale in much newer radiators that accumulates and encrusts the radiator core, as mentioned above. I also recommend a cooling system filter as your block may well have a load of debris that will unload and re clog in your newly rebuilt radiator.  What you can't see can hurt you.  Hope this helps, James

LaSalle5019

This is an inexpensive coolant filter solution that was posted in the AACA forum

https://forums.aaca.org/topic/381501-grimys-sock-cooling-system-filter/#comment-2526212

Bob Schuman

The block may still have significant deposits in the water jackets, depending on how it was cleaned before rebuilding. A September 1947 issue of the Cadillac Serviceman covers a flushing procedure, that for me removed lots of crud from my 41 engine that I had thought was clean. A copy of that procedure is attached, I hope.Caddy back.JPG 0]Cadillac Engine Cleaning Procedure.pdf[/attach]
Bob Schuman, CLC#254
2017 CT6-unsatisfactory (repurchased by GM)
2023 XT5

Bob Schuman

No idea how the convertible photo got in my post, that photo is not in my files!
Bob Schuman, CLC#254
2017 CT6-unsatisfactory (repurchased by GM)
2023 XT5

KenZ

#8
Lots of flathead overheating discussion in the past on this forum that you can search.  I have been thru leaps and bounds with mine running hot over the years and finally found resolution.  Everyone's input above is right on. I cannot over emphasize the importance of a known clean correct radiator for these engines.  As stated by Bill Ingler you need to have the top tank off the radiator to be positive that there is no obstruction or crud.  If you have to recore, make sure you replace with a correct core from an experienced reputable radiator shop that  is familiar with these radiators.  Original design, rows and thickness are crucial.  Good Luck and let us know how it works out.  KenZ             

V63

At one time There were offered some 'improved' water pump impellers to improve water flow.
Had success with that upgraded. I would definitely source again if need presented.

James Landi

 Decades ago, I purchased in 6 year old 61 Cadillac and had my mechanic back flush the cooling system... he used a cone shaped device with an inlet for water and compressed air  that he forced into the upper radiator hose,( he had taken out the thermostat and detached the lower radiator hose).  I was shocked by the amount of debris that came out of a six year old block.  He then "power" back flushed the radiator-- flakes of white scale came out.   James 

Oliver Betker

Hello everyone,
Additional question:
Does it make sense to use distilled water to avoid Limescale deposits/scale deposits from regular water when topping up the system during the season?
I think I read somewhere that this would accelerate corrosion, but I'm not sure I'm confusing things.
I thought the question fits well with the given hints in this post.
Regards Oliver
1946 Cadillac Series 61 Coupe
1958 Chevrolet Bel Air 4door Sedan
1958 Wartburg 311 4door Sedan 900
1961 Wartburg 311 4door Sedan 1000
1963 Trabant 500 2door Sedan
1989 Trabant 601 2door Sedan
1966 Bulldozer T 100 MGP
1968 Bulldozer T 100 MGP
1998 Nissan Pickup Navara
2015 Ford Ranger Pickup
1978 MZ T 250/1
1992 Harley Davidson Fat boy

LaSalle5019

Reverse Osmosis is recommended over distilled. You will always need a corrosion inhibitor. I use No-Rosion in all my cars (the ones that just run water and the ones that run glycol).