pressure test results

[wengr]

hello, in my head warp thread it was recommended that I do a cooling system presure test. the result, not surprisingly is that the system loses pressure. it's actually a nice tool as it uncovered some small leaks here and there which I corrected, but in the end it still loses about 1lb every 8 - 10 minutes or so. this is provided the fitting sealed well itself as I had to use one of the expanding rubber plug universal fittings. but I believe it's ok. there is no oil contamination or milk on the cap. I supect the head gasket as I have bubbles in the coolant. however I also suspect an air pocket as sometimes the temp gauge will show 190 then all of a sudden shoot to full in a second, once it dropped to the bottom. has to be an electrical prob with the sender etc. or an air pocket. also the fan will not run. all 3 hoses at the thermostat get warm. I have tried all the common bleeding techniques. now it's leaking coolant from somewhere on the front of the engine, hitting a pully or belt, and spraying a fine mist on the driver fender. more likely waterpump failure or head gasket leaking coolant externally at the front of the engine?

[So Cal Mark]

most likely a water pump leak, very rare to have a head gasket leak to the outside.

[TulsaSpider]

So did you pull the plugs and listen at each cylinder to see if you can hear anything? The pressure loss could be your waterpump.

[wengr]

So did you pull the plugs and listen at each cylinder to see if you can hear anything? The pressure loss could be your waterpump.

no I ran out of daylight before I thought to try that. although it loses pressure pretty slowly so I wonder if I could hear it. I do plan to try it before I return the tester. anyway to hear better? would putting a tube in the spark plug hole help? or?

[TulsaSpider]

A tube is a great idea

[wengr]

ok here is what I did. removed the spark plugs. pressurised the cooling system. removed the metal probe and diaphram from a mechanics stethescope and inserted the open tube into the cylinders one at a time. I hear nothing. nothing at all and if there was something to hear I bet this method would pick it up because it transmits sound to your ears very effectively. system still loses pressure slowly which is no surprise as I now have a leak that I suspect is from the waterpump. I think my initial pressure testing(2 days ago) blew the waterpump seal? I pressurized to about 14psi which the fiat manual said was max allowed pressure.