Compression testing on the bench (cold) of my 2.5 liter S14 engine has produced some "mysterious" values -- has anyone else experienced this?
Normal values for years were in the 140 psi range when tested hot. I have used the same gauge and hose that screws into the plug hole as before, but in cold testing find the numbers much higher. Tested twice, forgot to block the throttle open the first time so repeated. 1st time came up with 163 psi avg with range of 180-145. 2nd time with throttle blocked open came up with 193 psi avg. with range 197-182 !! Leak down values on Cylinders 1 and 2 are 6-8% and on 3-4 are 12-16%.
Since the engine had been sitting for some time I was worried about how much oil would be on the cylinder walls so I added a small quantity to each cylinder through the spark plug hole before starting the tests.
The engine is used in my 1981 320i which has been used for years as a track car running SCCA events at Nelson Ledges and Mid-Ohio mostly with occasional trips to the Glen. It has about 17-18 hrs of track use at the moment. Rebuilt in 2001 after 30 hrs. of track time.
Any ideas?
Normal values for years were in the 140 psi range when tested hot. I have used the same gauge and hose that screws into the plug hole as before, but in cold testing find the numbers much higher. Tested twice, forgot to block the throttle open the first time so repeated. 1st time came up with 163 psi avg with range of 180-145. 2nd time with throttle blocked open came up with 193 psi avg. with range 197-182 !! Leak down values on Cylinders 1 and 2 are 6-8% and on 3-4 are 12-16%.
Since the engine had been sitting for some time I was worried about how much oil would be on the cylinder walls so I added a small quantity to each cylinder through the spark plug hole before starting the tests.
The engine is used in my 1981 320i which has been used for years as a track car running SCCA events at Nelson Ledges and Mid-Ohio mostly with occasional trips to the Glen. It has about 17-18 hrs of track use at the moment. Rebuilt in 2001 after 30 hrs. of track time.
Any ideas?
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