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

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.

what is wet and dry?

wet test is composed of squirting oil in cylinder to detemine ring sealing ;dry is without oil testing .

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.

reply
 

thank you all for your imput!