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Radiator/Coolant Pressure Overflow cap leaking air

89 volvo 740t

Radiator gave out and overheated, wife drove it down the road about a mile then pulled into a parking lot. We traded cars, I filled the radiator up and drove slowly home, filling the radiator along the way, and it never overheated again. I replaced the radiator and aside from causing a host of other leaks, all of which we fixed, the car does not overheat. However....

Yesterday morning I began hearing a strange whistling/whine sound coming from under the hood. When at idle at a light, car in drive, it sounds damn near like a work truck backing up, you know, the "beep beep beep" sound. When accelerating it becomes a continous whine.

I investigated it when I came home and discovered that the sound is coming from the expansion tank, expressly from the green cap. The cap is holding a tremendous amount of pressure back, so I am concerned that the coolant system is over-pressurizing. I am beginning to suspect an exaust leak into the coolant system....ugh...

A note on the performance though, the car is running pretty well. It shifts a lot smoother than it ever has before, and the acceleration seems better than before as well. On the other hand, it idles at 800 or so RPM, a lower rpm than before, and the turbo gauge hovers at 9:30-10:00 when the cars is first started. I have never noticed the turbo gauge showing boost at idle before and I find that very odd. Once I get going, the turbo seems to return to normal and show a boost at 7:00 or so at idle.

So, seems to me that I have head gasket issues, and I wondering if there is a way for me to diagnose this without expensive equipment. I don't mind doing all the repair work myself, barring of course, honing the head if it is warped....

Does this sound like a head gasket issue to you guys?








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New Radiator/Coolant Pressure Overflow cap leaking air
posted by  uniac666  on Tue Sep 28 15:47 CST 2004 >


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