Really having cooling system problems. New Rad, t-stat, w-pump, - no pressure!

[Corellian Corvette]

Really having a devil of a time getting my cooling system dialed in properly.

Pressure-tested the system and determined I had a terrible radiator. Took it to a local shop, had it re-cored and cleaned up (shop owner is a big Mopar fan so I believe the job was done right). I replaced the t-stat with a premium NAPA unit, which I tested and verified on the stove before putting in the car.

Water pump is an alumnium unit from Mancini racing, along with a new clutch fan, all new pulleys and belts, and a new rad. cap. New hoses too.

On top of it all before I took the rad out to be fixed, I cleaned and flushed the cooling system until the water ran clear.

I believed I left nothing to chance. I put the new radiator in this afternoon and I have exactly the same problem as before. No pressure in the system (hoses don't get stiff) and the radiator gets SUPER hot even though the upper radiator hose is cool-ish to the touch.

Now - the car IS on a slight nose-down decline.  Also (and I posted this question before), when I read the service manual I'm wondering which direction the t-stat goes in the housing. I put it GM-style, where the brass temp probe is facing DOWN (inside the front cover) and the little nipple is facing UP (towards the water pump housing). The manual makes is seem like they want it the other way.

Any help or suggestions here would be greatly appreciated. This is really frustrating me!

Thanks!

[firefighter3931]

It sounds like you've got a large air pocket in the cooling system somewhere.

The thermostat should be installed with the spring facing down and the nipple pointed towards the upper rad hose.

Ok, you need to bleed the system....here's how :

(1) get the car up on a set of ramps
(2) pull the rad cap off ( make sure the engine is cool )
(3) with the front end elevated, start the motor and let it run for several minutes.
(4) look down the rad for signs of coolant circulation....once the thermostat opens you will see some
(5) Keep an eye out for air bubbles in the coolant...if there was a large pocket the rad will burp and the coolant level will drop once the air pocket is purged.
(6) refill the rad to 1in below the top of the tank to allow for expansion.


Hopefully this does the trick. Let us know how it turns out.


Ron

[Corellian Corvette]

I'll try that tomorrow. Could the fact that the car is facing slightly downhill really cause this much trouble?

[firefighter3931]

Sure could....if there is an air pocket trapped in the back of the motor it won't self bleed. Raising the front of the car  should free any trapped air inside the system, particularly if that air is trapped at the back.


Ron

[Plumcrazy]

And when you're done make sure you can get heat from the heater.  That will show that there's no air trapped in the heater core.

[grouseman]

Did you change the rad cap as well? 

Is the support spring in the lower rad hose? 

Is there a leak in the heater core? 

Sounds like lots of air in your system, with the cold upper rad hose.  Park nose-up and run it, check and fill. 

[Corellian Corvette]

Thanks. I disconnected the heater core and installed the 2 heater hoses togehter. My whole heating/ac system is screwey and I wanted to take that out of the equation.