Hydraulic Lifter Noise? Oil Pan O-Ring 1997 - 850 - T5 77K

jeovaz · Post by **jeovaz** » 25 May 2007, 19:04

Just acquired a 1997 850 T5. Not sure if the noise was there or not when I test drove it, it was a hot day so I had to use the AC.... oh well.

I'm hearing the noise around 2000 - 2500 RPM, and it sounds like it disappear when the RPM reaches 2800 > could be that the acceleration noise drown the ticking noise.

If it is a hydraulic lifter, should it be audible when i start the engine in the morning? Or should it also be audible when I accelerate up to 3500 RPM or greater while in park? I only hear the noise when the car is running.

Also, I do not have any oil leaks. If the oil pan o ring is the culprit, there should be a leak visible, right?

Any help will be greatly appreciated.

Post by **pfeener** » 25 May 2007, 19:34

No leaks would be visable. The "O" ring in question is the one that seals the oil pan to the block where the oil pump sucks oil from the sump. What happens is the "O" ring shrinks a little and lets air get sucked in with the oil. The air in the oil migrates to the top of the engine and gets into the hydraulic lifters and causes them to partially collapse. This problem usually shows up with a hot engine at idle.