Water loss after run [Archive] - SaabCentral Forums

: Water loss after run

4th April 2007, 09:15 AM
Dear List,

My wife is running a 900 SE 2 litre turbo Sensatronic (converted to manual). The headgasket was replaced 10 months/10,000 miles ago by an independant specialist and has been pretty water tight until recently. During the last month it's been losing approx a half pint per week/100 miles with the expansion tank cap screwed tight.

As the weather has been cool we've been running the car with the system unpressurised until I get a chance to investigate the loss properly and this pretty much stopped the water loss. However at the week-end we needed to do a 400 mile round trip, mostly motorway and at up to 100 mph (this isn't a confession yer honour). All was OK until we were tooling around town at our desination and when we stopped, the car dumped about 4 pints of water on the road. On the return trip the car behaved the same way and we noticed that the temp guage was reading zero. Same story when my wife was in town traffic in Bristol yesterday morning.

Yesterday I started my investigation. I topped the system up with the engine running, then fitted the expansion tank cap without tightening. Took a 4-5 mile run to warm up - no reading on the guage. Stopped the car and took off the cap - no bubbles visible. As the car idled and got really hot, the level started to rise in the expansion tank, accompanied by a few bubbles. The fan cut in before the water started to overflow and tightening the cap stopped the rise. The guage cut in at "normal" at the same time the fan came on.

This morning, with the car cold, the tank level was normal. The guage started reading as the car warmed up, but then died.

Any ideas as to what's happening here?

4th April 2007, 11:26 AM
The cap on the reserve/expansion tank should always be on tight.

If the car is not warm by 4 to 6 minutes of running, then the thermostat is shot.

The cooling system should be serviced - including a pressure check.
Apparently the guage transmitter should be checked out... and the temperature guage..
This will reveal at least part of the head gasket condition - people change these, but do they re-new the bolts and have the head checked for trueness ???

And the age old question - how many miles ?

4th April 2007, 12:44 PM
The car is now on 133k miles, but pulling well and the heater works fine after a couple of miles, so the thermostat is OK. The headjob included costs of new bolts and a light skim to true up the head.