compression/leak down test numbers

[lilskyline240]

whats compression on a rb25det on a cold motor supposed to be? the place i want to order my motor from gave me test results of 230psi, 225psi, 230psi, 225psi, 230psi, 230psi and leak down test results of 10, 10, 15, 15, 15, 10

is this motor in good condition. never really got leak down test results before and not sure how low the % should be

[skillzilla]

Those are both actually pretty weak honestly. I would expect 250-ish and no more than 10% leakdown on any cylinder. Its cool for the place to have done it for you, but I wouldnt pay for it IMHO. Just that little bit of smoke at WOT will piss you off. Then again it was a cold motor like you said, so it may get more decent once warmed up.

[lilskyline240]

thats what i thought. 15% seemed kinda high to me. IM prolly gunna pass on this one

[lilskyline240]

do leak down test results change depending on if the motor is warm/cold?

[Darius]

Those are both actually pretty weak honestly. I would expect 250-ish and no more than 10% leakdown on any cylinder. Its cool for the place to have done it for you, but I wouldnt pay for it IMHO. Just that little bit of smoke at WOT will piss you off. Then again it was a cold motor like you said, so it may get more decent once warmed up.

Why do you expect 250-ish when the FSM shows a standard of 180 psi and a maximum difference of 14.5 psi between each cylinder? Maybe I'm not understanding the procedure that was done for compression, but yeah the leakdown percentages do look like they're on the high side.

[gawdzilla]

do leak down test results change depending on if the motor is warm/cold?

not really, but they do change based on the last time the motor was run and how stuck the rings are from sitting

[lilskyline240]

i thought thats what i saw for compression numbers per FSM. Now im totally confused

[gawdzilla]

best way to read a compression test is to just look for consistency across cylinders. if something is wrong, do the leakdown and find out where it is.

for all you know those numbers could just be made up by the place anyway, so why take the numbers so seriously if you're not performing the test by yourself?

[lilskyline240]

they sent me pics of the gauge on every cylinder

[Scott Buwalda]

A leak-down of 10 or 15 on each cylinder is actually quite good. It's a tight engine. Maybe throw some new rings in, but otherwise it sounds fine.

Scott

[lilskyline240]

anyone else have imput on the leak down test numbers?