the sun alone will cause pressure to build in the cooling system. Not much but enough to burp a little coolant out if you release the cap. here is my 90 after a head gasket change. notice the pressure dropped and two hours later it rose. If you lost all pressure after sitting then yes I'de be worried. thermostat housings are always a source of pressure loss as are loose hose clamps even the seals for the radiators plastic tanks.

anyways here is a 2 hour pressure test on my 1990. the second picture was a result of a loose hose clamp, after tightening and sitting notice the pressure just from sunlight made it rise again.

 

I did my pressure test on a cold engine for 10 minutes. Was that long enough?

I did notice that if I set the unit down on the tire, that the needle would drop just a little. So, I had to pump the pressure back up to 16 and hold it in my hand for 10 minutes.

 

Josh...if your car doesn't overheat, I would say you cooling system is up to snuff and you have no gasket problems. The water coming out of the radiator is normal with the cap off, as you are lowering the boiling point by de-pressurizing the radiator. gurgtles and farts in the system is completely normal, hot or cold.

 

Ok, thanks. I just thought it was odd how my Firebird didn't do this.

I still have some blue fluid left. So, I'll probably use it to test it instead of letting it go to waste. If exhaust was getting into the coolant, when could I test it with the combustion leak tester? Right after I start the car up, or wait till the thermostat opens up? Cause if I have to do it after the thermostat opens up, then I'll have a short window to do the test before coolant starts comming out.

 

The sun doesn't cause the water pressure to rise in an engine. More like the thermostat in the gauge is getting hotter in the sun would cause the needle to move slightly.

Once an engine is up to operating temperature or any temperature and shut off the temperature does rise a few degrees. Why, because there's no water circulating through the radiator and engine. No more fan to cool the water or antifreeze mix down.

Pressure that builds in the system comes down when the engine is shut off. When the water or antifreeze cool to the outside air temps the pressure is releived in the system.

Now, as I said days ago, buy a 5 dollar radiator cap and that's that. You're chasing a ghost that isn't there. Oh, do not use a pressure washer outside or inside your radiator, you'll blow the thing apart and then you will have leaks, you'll be buying another radiator.

 

Just take the car for a drive and enjoy it! Remember if it ain't broke don't fix it. Take it out and hammer it a little it will run better, and you will feel better for doing it. Remember to WAVE

 

either it's gonna go or it's gonna blow ..... have fun

 

In the first post you said Autozone had a blue liquid to test for CO gases in the coolant. I've asked around at various places and they never said they had that; what is it called? Maybe I just wasn't asking them the right thing.

 

I think it is a block test. They have a picture of the fluid and the tester on one of their mats that sits on the counter.

 

Ok thanks. Yeah, the radiator cap I replaced that 3 months ago, so that should be fine.

 

I was finally able to do the test. I let the car warm up while I was playing around with the HVAC programmer. So, the heat/ac was on while it warmed up. When it got to 190-195, I took the radiator cap off and siphoned out 1/3 of the coolant in the radiator.

I began to do the test, which was squeezing a ball sucking the fumes from the radiator into a tube that had blue liquid in it. After about a minute of doing the test, I went to check the temp and it was holding at 198-200. I did the test for a few more minutes and checked the temp, it was holding at 198-200.

So, I turned the heat/ac off, and kept doing the test, and a few minutes later I checked the temp and it was 207, so I turned the heat back on as last time when the temp got to 210+ coolant started coming out.

Anyways, I did the test for around 10 minutes just to be sure. The fluid stayed blue, so that is good. With the heat/AC on and idling, it looks like my coolant system is doing fine. But I'm still gonna pull the radiator and clean it. And pull the drain plugs and rinse the inside of the block with water.

Though, I may still have a rich problem, or spark problem. When I started it cold, it did fine. But the few times I reved it real good in park shortly after starting it cold, I got a couple of back fire pops from the exhaust when the RPM's were high for a split second. Don't know if that is normal or not?

 

NEVER rev up a cold engine; cardinal rule. Oil/fluid/lube doesn't flow as well when cold and you're just asking for trouble.

It's an old racer's rule; we even warm the differential lube and trans fluid before heading to the water.

Jake

West Point ROCKS!

 

Ok, thanks.