1989 944S2 Compression Test

[John Petersen]

This is my first time doing a compression test on a car. What would you read into the following results or have I done it totally wrong.....

Warmed the engine up to operating temperature at an idle and not for a 15 minute drive/blast as is recommended
Performed a dry test on the motor with the throttle open and all plugs removed
Results as follows #1-170lbs, #2-175lbs, #3-170lbs, #4-179lbs
Results with oil added (from a squeeze bottle so amount was not uniform) #1-205lbs, #2-205lbs, #3-200lbs, #4-200lbs

Thanks!

[Spring44]

This is an excellent compression test, since your pressures are all high and well within the desired 10% maximum variance between cylinders. Your cylinders only have a maximum of 5% variance from highest to lowest when dry and a maximum of 2.5% variance when wet . HTH

[John Petersen]

So the variance from Dry to Wet is not something to be concerned about? I did notice a bit of oil soot on the number one sparkplug. Not serious but there. I was recommended to move to a thicker oil.

[9FF]

Originally Posted by John Petersen

So the variance from Dry to Wet is not something to be concerned about? I did notice a bit of oil soot on the number one sparkplug. Not serious but there. I was recommended to move to a thicker oil.

You should do a leak-down test as it will compliment your compression test results by providing details about your valves/guides. Imo your oil in the cylinder is most likely from valve seal wear and not because of cylinder wear, thicker oil won't improve anything.

[TibetanT]

Originally Posted by 9FF

You should do a leak-down test as it will compliment your compression test results by providing details about your valves/guides. Imo your oil in the cylinder is most likely from valve seal wear and not because of cylinder wear, thicker oil won't improve anything.

Agree with 9FF 100% !

How many miles on your 944S2 ?
(Wondering about that fact since I am about ready to test my car with 150K miles on it.)