Normal Cranking Pressure?
- Thread starter Realmongo
- Start date
HISSIN50 said:
JT is correct, but from what I recall, you don't want to see more than 5-10% difference between cylinders.
HISSIN50 said:
I did a compression check and all cylinders except for 2 were right about the 150 mark. Number 2 was 130 and number 4 was 119. The engine is not burning oil, so I am guessing I have a couple of valves/seats in need of some TLC.
Matt is correct about the percentages - having them all within 10% is much more important than absolute numbers.
If wanting to roughly compare numbers to other members' numbers, one should:
Do the test on a hot motor.
Have the ignition and/or fuel system disabled.
Have the throttle at WOT.
Have a charger on the battery in case it drains as you crank.
On those two weaker pots, I would try doing a wet compression test on them. I would not at all be surprised if the pressure went a good ways up. If it does, that suggests your rings are letting a little compression bleed past.
A leakdown test is the next step up for further compression-based testing.
Good luck.
If wanting to roughly compare numbers to other members' numbers, one should:
Do the test on a hot motor.
Have the ignition and/or fuel system disabled.
Have the throttle at WOT.
Have a charger on the battery in case it drains as you crank.
On those two weaker pots, I would try doing a wet compression test on them. I would not at all be surprised if the pressure went a good ways up. If it does, that suggests your rings are letting a little compression bleed past.
A leakdown test is the next step up for further compression-based testing.
Good luck.
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