boiling over

[JMinSD]

My wife's '94 850 turbo wagon (125k miles) started blowing steam the other day. I figured that the thermostat had failed. I easily aquired a new one, performed the 3 minute operation and refilled the reserve tank. I started the car and let it heat up in cofidence that all was well again. I monitored the temp gauge that settled in at it's normal mid point. I took it a step further and held the tach at 1500 - 2000 RPMs for about a minute. After I released the throtle and it came back to an idle, the fan kicked on. The reservoir filled to it's limit, the reservoir cap cracked open (as in split on the top and side) and coolant and steam spewed out. A moment later, the coolant was sucked out of the bottom of the reservoir. Maybe 30 seconds later, the reservoir quickly filled itself again and began spraying all over again. This cycle repeated itself 3 or 4 times over the course of about 5 minutes. When I turned the car off the reservoir filled again with boiling coolant before it finally drained to empty.

Besides keeping my dog from drinking the spilled coolant, I could only assume that the termostat wasn't the issue. I've heard that the water pump on this thing rarely (if never) goes bad. I'm tempted to test the radiator before I jump in after the water pump.

Any thoughts?

[dpauto.com]

It is possible that when you refill the coolant, there was an air lock and you did not fully had the system filled. What you need to do is wait for it to cool down....loosen the thermostat housing....fill the coolant until coolant start coming out from the thermostat housing and then tighten up the thermostat housing. Finally top off the reservoir. Drive the car around the block and come back and recheck the level.

Dave

[JMinSD]

Thanks for the insight Dave. That seems to have solved the problem.

Jacque
San Diego, CA

[dpauto.com]

Aint no thang !

btw...how is the weather in San Diego ? I was a Volvo tech (team leader) at San Diego Volvo for 11 years.

Dave