Disappointing compression number on my Sr20det

[xcye12]

I just did a cold compression test on my Sr20det that I am about to install.
Here is the result:
#1 136psi
#2 138psi
#3 96psi
#4 98psi

I phoned the vender, he said that once I installed engine and warmed it up the compression would go back to normal.

The thing warries me here is the inconsistancy of the numbers. It seems that there are problems with #3 and #4 cylinder.

Any suggestions? What should I do here? Should I return the engine to the vender? :loco:

Thanks for any help!

[Eternal_240Sx]

through my experiences, even though the engine is cold it still should be consistant no matter what. I highly doubt that a simple warm up would fix something like that.

[Eternal_240Sx]

also, after you install the engine it can be very difficult to return if the vender blames the problem on install. So its really up to you.

[HaLo]

Compression testing does not change from cold to hot... ask for an exchange...

[wootwoot]

definitely ask for an exchange.

[sepulchral]

thats fucking ridiculous, my heart goes out to you, ask for an exchange, don't they compression test the motors before they ship them?

Oh yes and if he wont do an exchange ask for compensation suchas pistons, rods etc.. thats terrible compression for an sr. Use legal force if nothing else works

[sepulchral]

Oh yeah and compression doesnt change from when u start it up thats just a myth cuz some of the valves might be open or something but it doesnt really matter because you turn the crank anyways.

[DuffMan]

On my motor the compression was 145, 140, 125, 125 when it was cold. When it warmed up it was about 150, 150, 145, 145 so it can get better when it warms up. Probably the valves seal better when their hot due to expansion. 96 is worse though, but maybe it will be okay, hard to tell.

[wootwoot]

yes there is a difference between hot and cold, wet and dry. but you use those differences to diagnose the problem. it doesnt mean thats its ok that they are low cold and high(er)warm.

[xcye12]

Here are numbers again ... After pouring oil into cylinder #2, and #3:

#1 140
#2 176
#3 141
#4 119

Any throughts?

[mrmephistopheles]

are you testing at WOT?

[uiuc240]

do a leak down test...it'll tell you even more than a simple compression test. then you'll know if it's the rings or the valves that aren't sealing up.

Eric

[xcye12]

Pouring oil into all four cylinders.

159
153
152
152

The battery is a little weak now!

[HaLo]

are you actually putting oil in the spark plug holes?

[sr240mike]

This may sound dumb but how do you compression test it out of the car? I've only done a leakdown test with it out.

[HaLo]

plug the battery on the starter and crank her up. ;)

[sr240mike]

Thanks halo. So was there any oil in the car when you first cranked it xcye12?

[xcye12]

Yes, I put oil in through the spark plug hole.

Yes, there is oil in the oil pan. I drained and refilled engine oil before doing any testing. I also found that there was only about 1.5 to 2 litter of oil in the engine before I drained it.

[HaLo]

Yes, I put oil in through the spark plug hole.

Yes, there is oil in the oil pan. I drained and refilled engine oil before doing any testing. I also found that there was only about 1.5 to 2 litter of oil in the engine before I drained it.

Are you sure that is a good idea? Oil should never get in the combustion chamber... of course compression will be higher, oil does not compress...

[balmo]

good thing it evened out when you put oil on the spark plug hole. consistently check the compression. if there is still a big drop bet. 2 and 3, go ask for an exchange. goodluck

[xcye12]

Are you sure that is a good idea? Oil should never get in the combustion chamber... of course compression will be higher, oil does not compress...

A little bit oil in the combustion chamber does not do any harm. One teaspoon or two are all fine.


Maybe the engine was just too dry when I was doing the initial testing. It might have been sitting some where for years. Or someone had tested the first two cylinders with oil in them.

I will do one more test tonight after the oil drain away a little from the cylinders.

I contacted the vender already. I was told if the compression did not reach normal after I installed and warmed it up, he would refund the money to me. That sounds good to me. But I still do not want to waste time to go through another installation if that happens. :x:

[SlamMan]

Who was your vendor if I may ask?

[wootwoot]

tell him ok but they are swapping it out the second time while you watch and you want compensation for gas and time consumed

[xcye12]

Who was your vendor if I may ask?

I will wait and see how things go. You can send me a PM by the end of this month. I may be able to tell you who he is.