Compression test on L33- this look okay?
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Teching In
Joined: Oct 2015
Posts: 22
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Compression test on L33- this look okay? Ran a compression test tonight on the junkyard L33 with 799 heads I bought recently. Motor has 158k on it. Test was run on a stand since this is just a long block.
Numbers were as follows:
#1- 220
#2- 202
#3- 215
#4- 208
#5- 190
#6- 220
#7- 215
#8- 230
#5 is a good bit lower than most and has me a little worried. Plugs didn't have any buildup or anything on them, but definitely did not have much left on the electrodes. My mechanic friend suggested running a leakdown test- anything I should be looking out for on this motor? Seems pretty healthy other than #5.
Numbers were as follows:
#1- 220
#2- 202
#3- 215
#4- 208
#5- 190
#6- 220
#7- 215
#8- 230
#5 is a good bit lower than most and has me a little worried. Plugs didn't have any buildup or anything on them, but definitely did not have much left on the electrodes. My mechanic friend suggested running a leakdown test- anything I should be looking out for on this motor? Seems pretty healthy other than #5.
Carbon wouldn't result in a difference of 40 psi.
I wouldn't worry about it. Realistic causes are valve seats, cylinder out of round, small scratch in the cylinder wall from the ring ends, etc.
I wouldn't worry about it. Realistic causes are valve seats, cylinder out of round, small scratch in the cylinder wall from the ring ends, etc.
TECH Addict
Joined: Mar 2013
Posts: 2,628
Likes: 30
Decarbon the engine and they will come down to normal. Normal would be in 150-185 range. But since you have no idea how well your gauge is calibrated I wouldn't put too much stock in the readings regardless. The leak down tests tells all. Still needs decarboning though badly just from the difference in the readings.
Last edited by RockinWs6; Mar 13, 2016 at 07:19 AM.
