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7 Series (E23, E32, E38, E65, E66)General discussion and technical help for all year 7 series cars.
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Your Ride: 1998 740il
compression Limits
I am new subscriber and in need of some desparate advice. i have a 1998 740il m60 engine w/ 130,000 miles, i finally did a compression test.the psi results are as follows: dry test- cylinder(s) 1-175,2-125,3-125,4-185,5-170,6-140,7-165,8-155 now comes wet test: cylinder(s) 1-180,2-165,3-180, 4-195,5-185,6-190,7-200,8-185 do you folks know what the limit range is for this engine? My foremost problem is misfire. I was strongly advise to start with compression test to first rule out any mechanical problems prior to testing fuel and electrical issues. Your collective opinions most appreciated!!! das kommisar12
I am new subscriber and in need of some desparate advice. i have a 1998 740il m60 engine w/ 130,000 miles, i finally did a compression test.the psi results are as follows: dry test- cylinder(s) 1-175,2-125,3-125,4-185,5-170,6-140,7-165,8-155 now comes wet test: cylinder(s) 1-180,2-165,3-180, 4-195,5-185,6-190,7-200,8-185 do you folks know what the limit range is for this engine? My foremost problem is misfire. I was strongly advise to start with compression test to first rule out any mechanical problems prior to testing fuel and electrical issues. Your collective opinions most appreciated!!! das kommisar12
your "dry" numbers suggest you have a big problem with 2 and 3 but the "wet" look to be fine, with compression its not so much the number but rather the consistency of the numbers in all cylinders, as a rule 10-15% or less in variation would be ideal.
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Your Ride: 1994 BMW 525i, 1987 325is, 1986 325
You may have a carbon build up issue causing your numbers. Has the car had its regular maintenance since new? (if no, or not known assume it hasn't). You could try to take it in for a de-carb treatment and that MAY help. But based on your test it would appear your issue is occurring in your cylinder heads.
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Big Evil, The BMW driving monster of the American Southwest (Currently on BMW #5)
08-19-2011, 09:56 AM
compression Limits
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