64slvrvet2

I have an overheating issue and the technician that is very good has checked everything.

Radiator temp is dropping 26 degrees from inlet to outlet on the radiator

But we just discovered that water is not pulling from the reservoir / expansion tank into the radiator. When we left some water out of the radiator it did not pull any water from the reservior / expansion tank to fill the radiator.

Any suggestions would be very much appreciated.

wombvette

That is just a T fitting. Water doesn't do much flowing through that tank.

mikey

remove the t-stat and make sure that's not the problem..

could also be air stuck in the system..

kingwoodvette

If system is low and reservoir has fluid, it should pull from res as coolant cools. Check line from radiator to tank to make sure there is no vacuum leak.

Bluestripe67

I think you need to start over. Drain the whole system, including the block drain plugs. Refill via the thermostat opening on the manifold. System should hold almost 4 gal. Bring it to operating temp and check the tank, top off as needed.

MikeM

I can see your problem immediately. Fire the "techy" guy and get a mechanic to fix your problem. Techs don't know anything about old cars.

mikem350

Sometimes its hard to fill the system because the thermostat stays closed and you THINK you have enuf coolant in!!!

I drill a small hole or 2 in the thermostat to let air escape for the initial fill. This is overkill, but it works. Of course, if you can run the car long enuf the thermo will open and then you can fill the tank up..MAKE SURE ITS FULL. May take a couple hot/cold cycles, just like a new car!!

Another possibility is a bad rad cap..seen that a lot on new cars.

So...to have flow the system has to be FULL...tank too

Fawndeuce

I may not be reading your post correctly, but you want the tank half full when the engine is cold, not full.



Paul

64slvrvet2

Cap has been replaced, no leaks in the system, tank is just below half full when cold, system has been pressure tested, tstat has been replaced.

I have not had the fluid drained and refilled thru the tstat opening -- will do that tomorrow. It has been burped but will try that again!

Thanks you all very much - keep the ideas coming!

MiguelsC2

Now they are replacing Drs with "techs".

MikeM

Before you chase your tail any further, how about providing some insight on your perceived problem, starting with, how do you know it's overheating? When does it overheat? How long have you owned the car? How long has it been overheating? Past service history? Etc., etc.

wmf62

yep, there is some flow through the tank. the vent hose from the radiator to the tank is under pressure from the water pump and should provide some flow.
Bill

Powershift

You should have a small vent hose running between the aluminum radiator and the expansion tank. There should always be some coolant flowing through this hose, it keeps the radiator full and vented.

If you haver a brass replacement radiator, this could be a problem.

What radiator are you running now, and does the vent line have coolant flow through it?? Check this with the expansion/radiator cap off on a cool engine. Check this as the engine warms up and the thermostat opens.

Larry

wmf62

take the cap off, pull the vent hose to the tank hose off at the tank and put the end in a can or point it somewhere that it won't be a problem, then briefly start the engine and see if there is flow.
Bill

65tripleblack

YOU WON'T SEE FLOW IF THE RESERVOIR IS AT NORMAL FLUID HEIGHT!!!

Drain some coolant until the fluid level is about 1" in the reservoir. Once the thermostat opens, you'll P L A I N L Y see fluid flow in from the small hose out of the radiator on the side of the reserve tank, and out the bottom to the heater and water pump.

You might ignore this advice. You should listen, in spite of where it;'s coming from.

64slvrvet2

Radiator cap was checked and is fine - system holds pressure - have not looked for flow in a tank that is only 10% full, will do that next.

New Griffin Radiator was put in before the engine was rebuilt 3-4 years ago and the overheating issue has been a problem since the rebuild.

Shroud is sealed for good air flow.

Thermostat was replace and engine was run without a thermostat or cap on the tank, to get any air out of the system.

Heat gun shows radiator inlet temp about 250 and outlet about 220.

JohnZ

What's the engine package you're trying to cool, and does the Griffin radiator have a clamped balance hose from the top right of the radiator to the inlet tube just below the top of the expansion tank?

Your radiator inlet temp (250*F) is 50*-70* higher than normal, driven by the water pump inlet temp of 220*F.; your radiator isn't doing its job.

MikeM

Amazing, ain't it?