'29 A Town Sedan, over heating

R

Ribbon clerk

Junior Member
Runs for about 10-15 min and overheats. Put new radiator cap with thermometer on and after 10 - 15 min of normal driving it boils over and the temp shorts to the top of the thermometer.
 
Do not fill radiator within 1" of the top. May want to drain and refill the system.
If it still overheats then we need to know how some history behind the vehicle.
Wick
 
Treat with a detergent like dawn and backflush radiator of possible grease oil.


Do the detergent 1st, Then a treatment or 2 of thermocure, rust 911, or evaporust - Back flush through the radiator. Detergent 1st, these products are poor at flushing grease/oil. then before running add an upper hose coolant filter like a Gano. Do not want anything that breaks loose clogging up the radiator.


If still an issue try shooting the radiator tubes with a IR temp gun, if you find cooler/cold spots, tubes are partially or totally plugged.


If still overheating/no improvement have radiator rodded out at a radiator shop.


Flow testing only works on radiators that are very bad, And sometimes testing at radiator shops can be false positive/thinking the radiator is ok.
A radiator can flow ok, but poor fin contact with the tubes due to age decreases a radiators ability to cool sufficiently.


If your radiator is really old, may be time for a new one. or a core replacement.


When I back flush prefer to back flush into a large plastic tub to see what comes out. The above products typically kinda dissolves rust scale, but you may see a few flakes and some grit.


If you research more and use white vinegar, be aware it can remove the grease in the original design type water pump causing the solution to leak and get all over. After the last treatment of white vinegar, do a treatment of baking soda/water to neutralize the acidic content of the white vinegar.
Simple flushing/backflushing with water is not good enough. This is similar to if you splash/spill battery acid, just a weaker concentration
 
As Wick said above make sure it isn't too full the motometer measures steam, not water temp. It should be just above the core. If there is too much water it will look like it is overheating and then puke out the excess.
 
Get a meat thermometer and test the temperature before buying a new radiator.
Moto Meters are a neat accessory item but not usually very accurate.
You/we need to know for sure what the temperature is before going too much farther.

How is your timing set??
If it is retarded it will cause overheating.

Had a friend purchase a new radiator because his car was overheating similar to yours.
I set the timing correctly before he installed it and he was able to send the radiator back. Saved a lot of $$$'s.
 
Sorry this has taken so long to get back in the forum; had a wedding to pay for.


Have pulled the radiator and filled it with white vinegar and let it set for about 5 days then drained it and back-flushed it with water. Had the radiator flow tested and pressure tested - both OK (but since this is not a pressurized system, does that matter?).
Also removed the water pump, plugged that port and filled the engine with white vinegar, let it set for about 5 days, then drained it and back-flushed it with water - 3 times (that's another reason it has taken me so long to get back here).
Additionally, I re-assembled everything but left the top hose off and filled the radiator and engine with water, started the engine and, at idle, very little water was pumped out of the return port. As I revved the engine, the water pumped out much,much better.
I reconnected the top hose and it still over-heats in about 20 min at idle. I assume that over-heating is when it boils the water out, right?
I am thinking that my next move will be to remove the head, the pan, and whatever else I can to get to the water ports and try to "rod" them out.

Yes, No ?????
 
Also, as history, prior to this spring ('19), the car had not been started for about 20-25 years. As to the cooling system, it had antifreeze in it. (I have already drained and flushed the fuel tank, rebuilt the carb, changed oil, trans and differential fluids.)


Someone mentioned that the timing may be off. But I used the little piece in the front and timed it that way, besides the spark advance lever changing the timing, so how could it be that much out of time?
 
Ribbon clerk said:
Also, as history, prior to this spring ('19), the car had not been started for about 20-25 years. As to the cooling system, it had antifreeze in it. (I have already drained and flushed the fuel tank, rebuilt the carb, changed oil, trans and differential fluids.)


Someone mentioned that the timing may be off. But I used the little piece in the front and timed it that way, besides the spark advance lever changing the timing, so how could it be that much out of time?
Click to expand...

If you timed it by the book and run with the lever at least halfway down I would doubt it’s your timing.
 
You need to take a laser temperature gun and check the top core of the radiator and see what temperature your getting. Maybe somewhere between 150 to 200 degrees? After that, check the bottom core and see what you have. Maybe 110 to 140 degrees? If that is the case, you are simply overfilling the radiator and it is barfing out the excess.
You must remember that this is a thermo-syphon (BARF) cooling system with a water pump hung on the engine to assist.
My 1926 Model T thermo-barf system without a water pump, cools oh so well. It is even a three tube crap for a radiator from the era. Everyone tells me that it can't possibly work, but it cools as good as the day it was born.
Tom L.
 
Just saw your post about having antifreeze in the vehicle. How long was the antifreeze in before cleaning everything out?
I have a Mercedes 230SL that had been sitting for over 15 years before I got a hold of it. The antifreeze had turned to acid and ate holes into the thermostat and water pump housings.
If that antifreeze has been in there for a real long time, possibly, your cooling system is all plugged up from corrosion.
Tom L.
 
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