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Old 08-26-2002, 12:56 AM
Mike Richards Mike Richards is offline
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Join Date: Dec 2001
Posts: 565
Wink 126 coolant loss problem solved

Reported a problem with coolant loss awhile back.

M103 - Tesing for combustion leak into coolant

A few months ago, I hired a local independent to replace head gasket and a ton of other work. Car was lossing coolant from the get-go after the shop worked on my car. Went back several times. Indy unable(or unwilling) to resolve problem. Previous experiences with him had been good.

Began to wonder if system was "drinking" coolant; however, no steam or loss out back-end was noticed, nor was there any excess coolant temp or fluctuating temps as it often the case with a leaking head gasket. No bubbling/gurgitation in pressurized overflow tank with cap off and engine idling and no signs of coolant anywhere else in the system. No coolant on the garage floor. Where could it be coming from?

Went to Auto Zone this morning and rented a cooling system pressure tester. Cap held steady at 20 lbs. Not surprised. It was new.

Hooked up tester to expansion tank neck and set pressure to about 17 lbs. System is supposedly 20lbs., but I had read in automotive text books that TOO much pressure could weaken the water pump gasket. In no time, I saw coolant dripping from underneath, back around the firewall. Was unable to see exactly where it was coming from. I knew it was around the monovalve. Removed windshield washer tank and battery to get a better look. Sure enough, I saw it dripping from underneath the monovalve. Studied a diagram of the monovalve and was puzzled about it dripping from underneath. Reviewed the work order written by the shop. Monovalve insert.diaphram replaced. Small rectangular shaped plate on top held down with 4 screws. Tightened them down, then put the pressure tester back on. It held at 17Lbs. for 15 mins and no more leak.

Not happy I had to redo a "pros" work, but this is certainly not the first time this has happened.

Thought I'd share this. Hope it helps someone else down the road.
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