CCCP

So I think I may have a coolant leak. Would a cooling sytem pressure tester pinpoint the exact location of the leak? I am under the impresion that it works by attaching to the resevoir tank, and after you pump it up to a certain psi and leave it for a few minutes, the pressure reading will drop if you have a leak. But since I am pressuring the system would I actaully see coolant leaking out of places if I look while its pressurized? Or would it just be air that is leaking out?

944Ecology

You might get lucky and see where the coolant is leaking out, our you might have a leak into something hidden (like a cylinder).

You will only see air leaking out when you have run out of coolant.

gb

CCCP

Ok, but if I pump up the pressure quite high I should see a nice steady leak correct (I am sure it leaks externally)? Which pressure tester should I buy? And to what psi should I pump?

944Ecology

Maybe you will just have a couple of drops... it might take a bit of time to see the leak. Or, you might see a stream of fluid. I've had it both ways.

The industry standard for this kind of tester is made by Stant, copied by many. Pump the pressure up to slightly less than the system specified pressure (it's marked on your coolant reservoir cap) which is 1.0 bar (14 psi) for early cars, or 1.5 bar (21 psi) for later cars.

gb

Epic2112

yep, the stants are great, and they can be had for relatively cheap on ebay (~$30)

ELLSSUU

Don't severly overpump or you may create leaks and obviously if it's your rad. cap leaking then you won't find out using the pump.

Serge944

Pressurize to 1 bar and wait patiently. Only coolant will leak...because it's pressurized.

If you can't trace it, pull your plugs and make sure none of them look "steam cleaned." You could have a HG leak.

racerx7

If your pressure does not hold and you still can not find a leak. You can get one of these kits
http://www.uview.com/homepage.html

You put the dye in your coolant and they use a special light and goggles to look for where the leak is.

Good luck.

Granite 944

I have the Stant tester kit myself. I do like it. It does help to find external leakage, tests the tank cap, and is very helpful in bleeding the system.

As said above, you shouldn't need to pressurize system more than about 10psi to find most leaks. Never reccomend going over 1bar (14.5 psi), or as said above, you can overstress gaskets/seals in the oil cooler, the radiator/core/hoses, and such. I've had some leaks that are real hard to find, but if I pressurize the system to about 12psi, let it sit overnight, if its an external leak, it will become apparent what and where. I just used it last weekend to find a stubborn one that turned out to be primarily the gasket under the thermofan switch leaking. Pressure left on it over night was the only way I could have found that for sure. Even if its a head gasket leak, if you put the tester on the tank without pressurizing system, run the car for a while, it could let you know if your getting pressure from the combustion chamber. Not all head gasket leakage problems are created equal, so these testers may not be any help in diagnosing a head gasket problem. But can still be a very helpful tool.
Yep, I find it to be an invaluable tool. Good luck.

F18Rep

It worked great for me, no way I would have found all of the leaks without the tester.
http://www.arnnworx.com/h2o-pump.htm
Bruce