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Old 02-12-2011, 11:11 PM
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Flug540 Flug540 is offline
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Location: Hayward, CA
Join Date: Nov 2009
Posts: 606
Mein Auto: 1998 BMW 540i 6-spd
Originally Posted by Quackers View Post
Me too, definitely more than 6 cranks!
What kind of fitting is used? Is it threaded? Does it seal well?

Also, has the car only been used on very short journeys? 80k is no mileage for worn piston rings, but premature wear can be caused by constant cold starts and cold running.
If the car is consistently used on very light throttle settings the top end can coke up quite badly (carbon deposits) which can affect valve seating. Maybe that's a possibility, but a long shot,perhaps.
Bentley says that the pressure should reach its maximum within 4-6 stokes, which in my case proved to be true. Today I went for a drive and did the compression test again. This time I did over ten strokes, but I noticed that the maximum was reached after 4th or 5th stroke. The fitting is threaded and seals well as far as I can tell.

In the period that I own the car, it is mostly used to commute 2-3 times per week 30 miles one way of spirited driving I always give it a chance to warm up. The owner before me was a lady who used it for short shopping trips and to drive her kids to school.

I disassembled the top of the engine today, here is a video of what the intake looks like:

I think this sludge build up can affect the function of the valves. Any thoughts?

Last edited by Flug540; 02-13-2011 at 07:42 AM.
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