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  #21  
Old 12-13-2021, 01:11 PM
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Quote:
Originally Posted by X5chemist View Post
The cylinder wall will be toast.
Ouch!
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  #22  
Old 12-13-2021, 01:13 PM
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Originally Posted by nick325xit 5spd View Post
Scope the bores before you do anything else at all.
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  #23  
Old 12-15-2021, 12:35 PM
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Quick update : I did a leak down test on the cylinders. 4 of them actually showed only 10% loss but when I quickly did a compression test I only see 10 psi. How would that be possible other than 2 different compression testers being inaccurate?

There are some scuff marks inside cylinders but I can not tell how bad the damage is by just looking.

One other thing I noticed is most of the spark plugs had oil on them which I believe is because there was still some oil inside the cylinders when I was trying to start the car. That also made me believe those plugs did not fire because of oil presence. I will clean them out (or just use new ones) and eventually try to start the car again..

Thanks,

Ozzie
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  #24  
Old 12-15-2021, 12:43 PM
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Quote:
Originally Posted by turquise1 View Post
Quick update : I did a leak down test on the cylinders. 4 of them actually showed only 10% loss but when I quickly did a compression test I only see 10 psi. How would that be possible other than 2 different compression testers being inaccurate?

There are some scuff marks inside cylinders but I can not tell how bad the damage is by just looking.

One other thing I noticed is most of the spark plugs had oil on them which I believe is because there was still some oil inside the cylinders when I was trying to start the car. That also made me believe those plugs did not fire because of oil presence. I will clean them out (or just use new ones) and eventually try to start the car again..

Thanks,

Ozzie
Leakdown is a static test. Things may seal at one specific point in the bore, but leak a lot in motion.
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  #25  
Old 12-15-2021, 01:01 PM
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Quote:
Originally Posted by nick325xit 5spd View Post
Leakdown is a static test. Things may seal at one specific point in the bore, but leak a lot in motion.
I am not going to deny you have a point but out of curiosity, what is the point of doing a leakdown test if it gives such inaccurate results? And I know most mechanics claim they'd prefer a leakdown test over compression particularly because it will tell you where the leak is. I have done the test both at TDC and BDC (both times valves closed) and got the same result. So in any moment of piston travel the whole compression would be gone because of a horrible damage done by bore wash although I made sure there was oil in there most of the time. I would like to also add the engine never was warm so the metals may not even be expanded enough to damage each other.

What about the oily spark plugs, you think they were working in such condition?

Thanks,

Ozzie
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  #26  
Old 12-15-2021, 01:34 PM
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Quote:
Originally Posted by turquise1 View Post
I am not going to deny you have a point but out of curiosity, what is the point of doing a leakdown test if it gives such inaccurate results? And I know most mechanics claim they'd prefer a leakdown test over compression particularly because it will tell you where the leak is. I have done the test both at TDC and BDC (both times valves closed) and got the same result. So in any moment of piston travel the whole compression would be gone because of a horrible damage done by bore wash although I made sure there was oil in there most of the time. I would like to also add the engine never was warm so the metals may not even be expanded enough to damage each other.

What about the oily spark plugs, you think they were working in such condition?

Thanks,

Ozzie
The short answer is that both leakdown and compression tests tell you different things. Compression tests also require a working starter. That's also why you would scope the bores. I would always do both if possible.

And no, I wouldn't expect spark plugs fouled with oil to work. Hell, too much fuel is enough to foul a spark plug.

Edit: The way that I would put it is this - If you're just trying to get a gauge for the health of a motor, I'd want a compression test. If you're trying to diagnose a motor, a leakdown test is *usually* more useful.
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Last edited by nick325xit 5spd; 12-15-2021 at 01:44 PM.
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  #27  
Old 12-15-2021, 01:42 PM
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I'm switching back to venting my pressure regulator to the atmospere instead of the air intake!
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  #28  
Old 12-15-2021, 01:46 PM
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Quote:
Originally Posted by nick325xit 5spd View Post
The short answer is that both leakdown and compression tests tell you different things. Compression tests also require a working starter. That's also why you would scope the bores. I would always do both if possible.

And no, I wouldn't expect spark plugs fouled with oil to work. Hell, too much fuel is enough to foul a spark plug.
I see some scuff marks but it is hard to tell if they would cause so much compression loss without touching them (I believe the test is to see if the scuff is 'noticeable' by touch). I may be able to extend the camera there to see if I feel anything. Or simply just give up and take the head off

Thanks again for all your input..

Ozzie
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  #29  
Old 12-15-2021, 02:00 PM
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Originally Posted by 80stech View Post
I'm switching back to venting my pressure regulator to the atmospere instead of the air intake!

I am looking at a new (used) Bimmer, possibly an X3 to keep my old X5 as a project car..


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  #30  
Old 12-15-2021, 02:37 PM
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The X3 is a newer platform and different fuel system so "I think" (I don't have a manual or diagrams for the X3) the fuel pressure regulator will no longer be a problem.
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