1999 528i cylinder 3 low compression

[T Jon]

My 1999 BMW 528i intermittently dropped its top speed to 20-30mph. Had the codes read by Advance which gave P0303 Cylinder 3 Misfire Detected, and P1580 Throttle Valve Mechanically Stuck. Took the car to an independent BMW garage. The garage replaced throttle body. A week later the car began to sometimes misfiring when started then ran rough, or started without misfiring and ran smoothly. Again had the codes read by Advance which gave only P0303 Cylinder 3 Misfire Detected. Today on the way back to the garage, the engine temperature began to climb into the red, so immediately parked the car and had it towed to the garage. The garage said cylinder 3 had low compression (20#s) which may indicate blown head gasket, cracked piston or cracked engine head. I asked them to pull the head and tell me what they find. Any suggestions?

[romanfishin]

Did you get the car fixed, interested if you found the problem. Thanks.

[Randyboyy]

Originally Posted by T Jon

The garage said cylinder 3 had low compression (20#s) which may indicate blown head gasket, cracked piston or cracked engine head. I asked them to pull the head and tell me what they find. Any suggestions?

I think you 'll better to change engine.....'

[Jack Dabsy]

Have you looked at the coolant and oil?
These WILL tell you if it is the head gasket...
If it is the rings on cyl 3 the why have the others not failed in maybe a slower fashion?

TBH I would deffo say Gasket failure.

[T Jon]

Pulled the head and found previous owner had helicoils installed in headbolt holes, versus timeserts which can be torqued tighter. Previously they probably just torqued as much as they could which was not enough to prevent leaking. Head passed a pressure test, so used timeserts and replaced head gasket and head bolts, along with repair or one bank of intake cam bearing stud holes which pulled out.

[Jack Dabsy]

So you had "stretch-bolts" fitted?