hey i juss hab quick question about compression and leakage test..
basically i hab 124,xxx miles on 98lude and i got 180lb on all 4cylinder and for leakage: 1. 10% 2. 30% 3. 20% 4. 70% <<little weird dat i made 180 with huge leak down.
70LEAKAGE on 4th cylinder...im plannin on boostin but as you can see(a terrible leak down test), i couldnt boost on dis motor..i still havent found out where is leaking from,,few problems: my engine oil is either leaking or burning fast despite the fact that i had 1000mile+ before oil chage, my engine was almost empty. and ofcourse air leaks too. i hab feeling about piston rings which i dont know squat about...any advice will help thx

 

wow... are you sure your valves were closed all the way ? What air pressure did u run it at ? I think your normaly supposed to run around 90 or so. 100 at most.

What kind of compression did it make ?

 

He said 180 on all 4 cylinders.

So thats super odd

 

oo ok he said something about lbs in there too which has nothing to do with compression, its usually measured in either Kpa or PSI. But i know what he meant. That is very strange. Do you have the break down of all the compression numbers ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lude98SH &raquo;</TD></TR><TR><TD CLASS="quote">oo ok he said something about lbs in there too which has nothing to do with compression, its usually measured in either Kpa or PSI. But i know what he meant. That is very strange. Do you have the break down of all the compression numbers ? </TD></TR></TABLE>

PSI = pounds per square inch

when you do the leakdown on that bad cylinder, can you hear air rushing back into the intake manifold?

 

It sounds like u didn't check each cylinder at TDC cause if u got 180 psi for all 4 cylinders I doubt u got those leakdown numbers.

 

A leak down should run at 100 PSI. You can run it lower, but it just makes the math a little more difficult.

I find it more strange that the leaks are multiples of 10. Usually you can get a lot more accurate with leak down numbers than that. e.g. my track car has 2%, 1%, 2%, 4% leak figures on a hot engine.

Also, the engine was at operating temp right?

 

If you're not very close to TDC when doing a leak down, the air pressure will push the piston downward and spin the crank.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JasonST &raquo;</TD></TR><TR><TD CLASS="quote">It sounds like u didn't check each cylinder at TDC cause if u got 180 psi for all 4 cylinders I doubt u got those leakdown numbers.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bluedlude &raquo;</TD></TR><TR><TD CLASS="quote">

PSI = pounds per square inch
</TD></TR></TABLE>

Umm yea.......