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Perplexing coolant system Posted by crawdad [Email] ![]() ![]() |
1997 SET 132K
This was first noticed after a couple of small pools of coolant appeared under the car after driving for 2 hours with the heat on, in ECON mode.
Pressure begins to slowly build in the upper radiator hose after engine is started and before thermostat opens. There's still some give to the hose but once the car is driven for 15 minutes or so, there's so much pressure, there's no give at all; it seems about to burst. If I remove the tank cap, the pressure is released and water level rises in the tank. I replaced the cap with one from NAPA thinking that something was wrong with the pressure release valve although it seemed to be ok. That didn't work. So I took out old coolant, ran the engine on water for 5 minutes without thermostat, put in new Saab coolant/distilled water and Saab thermostat. Didn't help. Now I'm about to retorque the head bolts since a previous post said the head gasket could be leaking although I have no signs of wet leakage - some soot near the #10 bolt - and the oil and coolant are clear. Spark plugs are normal gray. Temp gauge is at usual 9 o'clock. One other possibly relevant symptom is she started idling at 1100 at startup last month, whereas she has always idled at 1000. After warmup, she goes back to 1000.
If the retorque doesn't work, I guess I should do a leak-down/compression test? Anything else?
Also, why doesn't the expansion tank cap not release that pressure? Is it possible that it hasn't reached 20 psi yet even though the the upper hose is so distended?
Thanks for taking the time.
posted by 98.88.13...
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