I have an 82 240D which starts and runs flawlessly every time since I purchased it in August of this year. I wanted to test the compression of the engine to perform a trend analysis because I would like to keep this car a very long time. I bought a Craftsman compression tester that measures up to 300 psi. I've noted from the discussions from the group that the normal range should be around 290-300 psi,so I thought to myself that this will be adequate. My problem is that the compression tester threaded end is too large for the hole where the glow plug fits in. Has anybody in the group ran into this problem? Is there an adapter available that will address this situation?