The Stovebolt Site Forums The Shop Area Engine Shop Use Radiator Stop Leak...Now Overheating??!!!!

What the heck is going on here??!! I poured one of those cheap Solder Seal (now GUNK)radiator stop leakes in the leaking radiator to try and stop a few leaks...you know the kind that comes in a little pepper style canister? Now the engine wants to overheat! It ran right in the middle about 185 degrees or so before the stop leak...now it edges up to maximum. Any ideas? I hate using that stuff anyway. Grrrrrr!

BTW - Original 1942 radiator / new water pump/ 216 motor.

It is possible that the sealant clogged some passages in the radiator and now you have less cubic inches of radiator leading to less space for coolant to cool. There is always a risk of that when using those products. I have only used stop leak one time and I had good results but it was a new radiator that was bumped around pretty good in an accident. Other than some mist at one seam it was in good (almost new) condition.

What do you mean by maximum? Depending on your driving conditions (climate, load, traffic, etc it might be ok. If you are driving hard in a warm climate it might not get worse. If you are tooling around town on a cool day it may be much worse it he dead of summer.

I don't know if this helps ... you could have the radiator re-cored.

Rich

Might check the thermostat first to see if it is clogged

Oh yes, forgot to mention. This engine is on a test stand, not in the vehicle. It goes from cool to way past hot fairly quickly where as before it took a while just to get up to the half way mark then would just sit there. There is NO thermostat in at this time. The engine warms up pretty fast getting warm and the radiator water is still cool. The lower hose feels warm and the upper cold and water in radiator seems cool. Worse yet, not one leak came close to stopping.

Was the rad near full when you put it in? If the rad is low the sealer will lay on top of the tubes & plug them up.
I have used stop leaks ,mostly Bars leaks, for 60 years & never had a problem with it.

That is the problem, not the stop leak. The thermostat acts as a flow regulator in addition to temp. Without it, the coolant is flowing too fast through the system, not allowing it dissapate the heat properly. You need to install a thermostate, or at least a 3/8" id fender washer (old Flathead trick) to act as a flow regulator.

sounds exactly like the pump isn't pumping [rather than pumping too fast], or you added the SolderSeal when the engine was cold and low and it totally plugged the rad as George said

the lower hose should be cooler than the upper hose, and if the engine is overheating with no stat, that overhot water should be getting pushed up the top hose to the rad - everything would be equally hot, nothing "cold" or even "cool"

pull the bottom hose and see if water flows thru the rad freely - check if the pump is actually pumping

Bill

Bill,
Pulled bottom hose, both actually, and while filling the rad from the top no water at all was coming out the bottom outlet. NONE! darn stop leak. Put pressurised water through the rad and you would not believe the junk that came out. All is well now and the water flows freely out the bottom. Hopefully the radiatior will work better that before. Maybe a radiatior shop could solder the leaks on this one. Any ideas how much to re-core?

yes, some leaks can be repaired, it's not unusual for a rad with a good core to need the tanks resoldered after 50 years - hafta ask your local shop about a recore, have them test it and see if it needs one or is worth repairing .... meanwhile leave the cap loose and you'll have less leaking and less further damage .... but I wouldn't blame it on the stop leak, it has its uses and needs to be used properly

Bill

I paid about $300 to have mine done, but that was with a larger core than stock.

Test stand! Airflow through the radiator?

I've got a reverse-flushing adapter with a rubber expansion plug that fits the lower radiator hose nipple and allows me to goose a shot of compressed air into the outlet of the radiator after it's filled with water. A piece of rag wrapped around an air blow gun will do the same job, but it's just not as professional-looking! The radiator cap needs to be removed for this procedure. A quick shot of air sends the water backwards through the core, and dislodges most of the crud that's clogging the tubes. It can also open up pinhole leaks that have been stopped up by the deposits, however. Make sure to put a deflector around the radiator filler neck, or you'll flood the engine compartment, and possibly yourself, with dirty water! Stay far, far away from the powder-type sealers. As you've already discovered, they're just as good at clogging up cooling passages as they are for fixing leaks. Once the radiator is pretty clean, a bottle of Bar's Leaks would be the only sealer I'd consider using. It's a mixture of vegetable fiber and water-soluble glue.
Jerry