Radiator Overflow Puking at low temps?

Xavier · #1 (**permalink**) 05-15-2011, 06:43 AM

A year ago I was running a traditional overflow tank on the inside fender, a single 22psi radiator cap and a 50/50 mix of fluid and water with the same 190F thermostat I have today. With the use of the traditional looking push fans in front of the radiator and the puller behind it never over heated. I turn them on when necessary manually. At this time I had a 4 barrel carb.

Currently I am running with a Kirkrham FE style overflow tank with (2) 18psi caps (recommended PSI by KMS) one on the radiator another on the FE style tank. I run straight water with water-wetter. Same 190F thermostat with (2) 1/8" holes in it. I also went through a Weber 48IDA conversion (which I do not think make a difference in the problem but...).

In a 30 minute drive at 68F outside driving at 65mph to 80mph with 80c to 90c on my water-temp gauge the top line out of the KMS overflow tank is puking fluid underneath the engine. The fans of course were never turned on at these temps, why would I need to?

What the hell is going on?

392cobra · #2 (**permalink**) 05-15-2011, 07:25 AM

I'd bet you overfilled it.

After it finishes puking out,check the level again. It could be correcting itself to it's proper level.

Xavier · #3 (**permalink**) 05-15-2011, 09:26 AM

Okay, what is the correct level? I am filling the overflow half way.

One last thing... the 4 barrel to weber conversion does matter. I am running a 351w block and the traditional intake had the by pass hose running to the block at all times. Since the weber/FE overflow tank conversion, I have no place for the by-pass hose. Still hard for me to believe it would make a difference at such low temps but thought I would mention it.

392cobra · #4 (**permalink**) 05-15-2011, 10:24 AM

Quote:

Originally Posted by Xavier

Okay, what is the correct level? I am filling the overflow half way.

Yep,1/2 way and/or just above the baffle plate.

scaffold · #5 (**permalink**) 05-15-2011, 11:20 AM

If I fill mine up completely, it'll puke it out evrytime until it gets to the level it likes.

Gaz64 · #6 (**permalink**) 05-15-2011, 02:22 PM

It may be a case of block pressure rising high enough to lose coolant prior to the thermostat opening. This will happen if you have no bypass.

Tom Kirkham · #7 (**permalink**) 05-15-2011, 02:35 PM

Sounds like a bad radiator cap. Try switching the rad caps between the surge tank and your radiator. The surge tank should have no problem running with a system pressure of 22 psi. Also make sure the gasket on the radiator and the sealing surface of the surge tank are clean and defect free.

olddog · #8 (**permalink**) 05-15-2011, 06:18 PM

If all the above fails:

If you do not have all the air burped out of the heads, it is possible to have hot spots in the heads that is flashing to steam (making pressure and expanding). If you hear any gurgling when you shut it off, that is likely the problem.

Xavier · #9 (**permalink**) 05-15-2011, 08:35 PM

All good advice. Does anyone know where I can pick some good old-school looking radiator caps? I want seen a picture of gold zinc plated caps on a KMS Cobra, looked really good. Anyone know where I can pick something old school up? Mine look old school but have MADE IN CHINA in the largest font possible. I looked and looked and could not find anything.

PANAVIA · #10 (**permalink**) 05-18-2011, 05:14 PM

the mustang restoration guys have old school repros from Scott Drake , etc.