Last Lemming

I'm addressing some minor coolant leaks. I left the tester on all night and the psi dropped 3-4 psi. This is with a very minor leak. Once fixed what would be considered an ok drop say after 10 min and then say an hour then say all night.

I have to imagine some loss is to be expected?

Tom M'Guinn

I usually pump it up to 15 psi --let it settle for 30 seconds or so -- then if it stays steady for 10 minutes I call it good. Never tried it, but I best most systems would leak 4psi overnight -- probably most of which getting by the bladder in the filler neck. Slide clean white paper under the engine and look for drips under pressure.

plumbum

Not sure what you are using to pressurize, I use a snap on pressure guage and I would only trust it to be reliable for a quick test....If you think you have all the leaks fixed take er for a drive and keep an eye on the level