Easiest Way to Check for Cooling System Pressure Loss

[MickSaturn]

OK...so I swapped out my water pump and my radiator. I've lost about a pint of coolant in 60-80 miles. And when I drive it til it warms up and then go to loosen the coolant tank cap, there's a little pressure but not like what I would expect. If I recall in the past it would be like major explosion of coolant if I tried to remove the cap with a hot engine.

So I have a pressure loss somewhere. The coolant doesn't appear to be ending up in my oil because I changed the oil about 40 miles ago and it still looks good. Maybe one of the hoses?

So what is the recommended way for a DYer to find a tiny leak like this besides just feeling around and listening while the motor is running. I cab also pull some cardboard out and put it under the car to see if anything is dripping while it's running. But assuming nothing is dripping, how would you pressure test it and isolate the leak?

Thanks.

Mick

[Sky King]

To test a cooling system for leaks and its ability to retain system pressure you can do a cooling system pressure test with the engine off and cold. You need a way to pressurize the system to approximately 15 PSI. You can either buy or in some cases, rent a cooling system pressure tester. This is a tool that has what looks like a hand air pump and an adapter to the cooling system resevoir. You pump it up and watch the pressure gauge to see if it holds. Also while it is pressurized, you can look around for coolant leaking out.

You can also make a home made pressure tester. This is from another member, BarnOwl. He made this and from the looks of it, it should do very well. You still need a source of pressurized air.

Originally Posted by BarnOwl

You can do what I did to find the leak when I swapped engines. Make one of these:



Put it inline in the return hose at the top of the reservoir. I used one of those compressors that plug into the cigarette lighter and have a built in pressure gauge to pressurize it. No higher than 15 PSI. Also check inside the car once it's pressurized. I had a heater hose that leaked into the interior.

Well I tried to copy the post he made showing a picture of it, but apparently you can't copy pictures from one post to another. So I'll just get you a link to the thread.

Go here: http://www.saturnfans.com/forums/sho...d.php?t=112432 Not sure how far down it is but a post by BarnOwl has a picture of the pressure tester he made.