Jam421

Hi Guys....looking to solve a coolant distribution puzzle noting my engine is higher than the radiator. I'm assuming my rad is not clogged because a shop resolved this issue just last season. My engine reaches 180 degrees not more, upper hose heats up, right top/side of rad heats up but NOT across the top, center or left side.

My upper thermo cap is 16psi. The rad mounted cap is 13psi. Once the engine is running at a steady 180 for 5-10mins ...with rad only partially hot the 13# cap lifts and there's goes the coolant.

Could I get some advice on how bleed an air pocket ?
Should I start by slightly cracking the lower coolant escape valve since that's not even warm ?

Perhaps also remove the temp sensor to ensure the block is full ?
It's a new BP 383 which was fine after install except the thermo housing leaked. In my crazy thinking I'm assuming that's where the air pocket began as the shop removed & resealed the thermo housing.
ps: He didn't have a bypass thermo so that's next !
Pics of my set up. You can see where it spewed out to the ground from the rad cap. Thanks !

MelWff

why are you running two pressure caps especially with two different pressure ratings ? Install a 16# cap on the radiator and bleed any air by warming up with the higher cap removed. Once you see fluid moving reinstall the cap.

rustylugnuts

Have you done a compression test on each cylinder to see if it holds pressure, as you may have a bad head gasket?

rustylugnuts

1961 283/315 fuel Injection
25 year member NCRS

histoy

It appears that the inlet and outlet are both on the right side of the radiator, so you might be right about an air trap inside the radiator. I've read on some Mopar forums where folks with big block engines had a similar problem. The recommended solution was to park the car going up a hill, remove the radiator cap, then run the engine to bleed out the air. It might be worth a try in your situation.

Jam421

MelWFF....I ran a 16 up top with a 13 on the rad thinking if there was excess pressure the 13# would open dumping the coolant into the reserve tank , which if filled, would then vent to the street. Oddly the 13# rad cap did not vent thru the hose to the reserve tank at all ….it just lifted. That’s what I get for using an $8 Stant rad cap ! On follow up for that I removed the rad cap & blew compressed air thru the ¼” hose to reserve + removed the reserve tank cap and air blew straight into the reserve tank and also straight to the street from inside the tank. So the system is working. Perhaps the 13# Stant rad cap isn’t ? I offset the cap pressures to hopefully direct coolant to the street rather than have the upper thermo cap open on my polished motor. Why the 13# rad cap lifted without venting is a mystery.
I WILL swap that out for a NEW 16# cap for sure.
Histoy…Yes…upper inlet & lower hose to water pump on rad are both on right side. I tried to mimic the “ hill effect” with a floor jack under the front and will try to burp the system that way again adding a slight crack of the rad petcock to see if air hisses out as well.

I was hesitant about running the engine with the upper thermo housing cap off. But I will replace that thermo for one with a bypass as well before I try that. I might as well give it all a shot ! I will keep you posted.
Thanks Fellas……….

Westlotorn

As already mentioned if your system fills with air pressure quickly after start up the cause is normally a leaking head gasket or in some cases I have seen leaking heads, a crack that opens as the temp warms up.
Purging air from a small block is not a problem. As mentioned you just raise the burp point till it is the highest point on the engine and run the engine with the burp point open.
The best way is to fill an empty block slowly while the car is sitting in the most favorable position to burp the air. As you fill it slowly listen carefully and you hear the air escaping.
Stop pouring every time you hear air escaping, when it stops continue to pour. This takes some time but if you hear air escaping and continue to pour you can trap air inside.
On your corvette this would be the top radiator hose thermostat position. Take the thermostat out and fill from there, you will see when it is full. If there are bubbles you have air inside. Wait for them to purge. Fill the radiator the same way through the top hose.
Done like this when you run the engine after filling you will not need to add any additional fluid, it is already purged.
You mentioned opening the petcock to help purge air, this would be at the bottom of the radiator? All this would do is drain fluid.

Jam421

Westlotorn...I will not touch the rad petcock and will follow your advice by removing the thermo & burping the engine/rad...this week. Thanks Bud.

Jam421

Double post............sorry.;

Jam421

OK Fellas.....I swapped the basic thermo for a high flow Mr.Gasket with a 3 hole bypass.
I burped the intake according to Westlotorn's advice (thanks bud !) until the rad began to overflow.
I capped the rad & burped the intake bubble by bubble with the front end jacked up .
I also found the upper hose from thermo to radiator was "empty"..no coolant..just air.
Massaging the upper rad hose while slowly adding coolant to thermo housing resulted in many more big burps. I had to stop at that point due to other obligations.... but I intend to get back on the car this week ...run it from cold with the thermo cap OFF
to watch the coolant flow . Good Stuff .

Westlotorn

Forgot to mention your heater valve should be full open to fill the heater core. Sorry.

Bill Pilon

I have a Blue Point vacuum radiator filling system, put the filler adapter on cap opening, attach an air hose to unit, pull vacuum in system, wait a few minutes to see if it will hold vacuum, if it doesn't find the leak and repair it, if everything is ok put the hose from unit into a bucket containing your coolant, open the valve and the whole cooling system fills to the top, remove adapter and install the cap. I have never had an air problem using this system, even in vehicles noted for air block problems, ie: BMW and some Ford Trucks.

Bill

MikeM

That's the same basic process the factory used. Same with brakes and AC.

Jam421

I believe the problem has been solved thanks to the advice and support from this forum.
I was able to burp the motor starting with filling the intake & burping the upper hose thru the thermo housing. I now have 16psi caps on both the rad and engine . It's been thru 2 heat cycles in the garage and the gets hot on both sides/top/bottom.
Since the temps scoot right up to my 195 degree rad twin fan setting before being fan cooled back to 180 .....I will be considering a 170 stat and exploring if I can lower the fan setting towards the 190 range. Good Stuff. Much Thanks .