I'm using a 16LB radiator cap with the new motor. I had the radiator recored when I put the motor in...using a high-efficiency core... with 16 fins per inch rather than 12 which is OEM. The car has factory air, and the radiator is a 4-row unit.

Yesterday was the first day since I got it running that was warm...it was about 75 degrees or so when I first took the tops off her and went out for a romp. :cool:

As posted elsewhere, it really does run cool at 180-185 or so. The Thermostat is a 180 and it definitely works. My question is why it has absolutely no pressure in the cooling system??? ??? ????

After a couple of hours of running it hard, both on freeway and in-town driving, I saw the temp still at 180-185 which is what it was running on the really cool days that I drove it. :cool: :cheers: Now, I know that's a good thing but when I lifted the hood to check for leaks and such, I noticed that the top rad hose is limp. No pressure inside at all!~ Is that wierd or what??? :confused:

Also, to combat inside heat (the A/C does not work - needs a new evaporator) I just plugged off the heater hose connections at the intake manifold and water pump, when I put the engine in. I've never done this before, and I'm sure the water pump bypasses internally so this won't cause any probs. But could this for some reason be keeping it from building up pressure?

 

Forgot to note that with the oem engine, and the heater connected, there was always pressure in the system ... upper hose was always hard when hot.

 

Pressure on the radiator cap raises the temperature that water boils. With a 16 pound cap the water won't boil until about 265 degrees if I recall correctly.

You didn't mention whether or not this situation occurs with the engine running or off. If it is off, is it possible at the temperatures south of 212 degrees that there is no pressure in your system with the water pump not pumping? I don't know the answer. Hopefully someone with more knowledge on the subject will chime in.

If the engine is running is it possible that you have some air in the cooling system that has not worked its way out of the system yet?


[Modified by Bobchad, 4:13 PM 12/29/2002]

 

If the engine is running is it possible that you have some air in the cooling system that has not worked its way out of the system yet?


I guess that's possible. :confused: As I said though, the heater water outlets are plugged, so I doubt it. The engine actually was full of both water and oil for several days before I fired it. Of course there's no certainty to this but I have to assume that day after day with it sitting full of fluid, and the radiator cap off, that air would have surfaced.

 

Not necessarily if the upper hose is the highest spot on your cooling system. The air can get trapped in here as it will go to the highest point.