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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > Compression and leak down check



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      10-31-2012, 10:17 PM   #1
e90pilot
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Compression and leak down check

I've got 190,000mi on my car. For those worrying about engine life, here's my numbers:

Cylinder, compression (psi), leak down (%)
#1, 180psi, 10%
#2, 190psi, 10%
#3, 190psi, 10%
#4, 185psi, 10%
#5, 185psi, 5%
#6, 200psi, 5%
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      11-01-2012, 05:17 AM   #2
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Looks good to me for 190,000 miles on your car, did you do this yourself? if yes then was the test a Dry, Wet, or both? also is the leak normal for 10%, i'm guessing it shouldn't be leaking at all but a little should be fine.
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      11-01-2012, 12:10 PM   #3
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Not bad at all for 190k miles. Just wondering, how long you let the car warm up before testing since we dont have a temp gauge in our cars?
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      11-01-2012, 12:40 PM   #4
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Did you perform the leak down yourself or have a shop do it? Considering picking up a leak down test kit for $70 off eBay so I can do these tests myself.
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      11-01-2012, 12:56 PM   #5
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Done at a shop. Car was fully warmed up (drove from Oakland to San Francisco) which is good for the compression check but apparently not good for leak down. Leakdown "should" be zero but as the miles pile on, the cylinder won't seal as well as it did.
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      11-01-2012, 01:48 PM   #6
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Who was your Bay Area tech for the 3stage intake manifold install? How often do you do all the regular maintainance since you've had the car?

Last edited by Route 16; 11-01-2012 at 02:00 PM..
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      11-01-2012, 03:05 PM   #7
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Quote:
Originally Posted by e90pilot View Post
Done at a shop. Car was fully warmed up (drove from Oakland to San Francisco) which is good for the compression check but apparently not good for leak down. Leakdown "should" be zero but as the miles pile on, the cylinder won't seal as well as it did.

Both a compression and leak down tests are better ran on a motor that is at operating temperature. They can be ran hot or cold, however the more realistic numbers would be with the warm motor when the rings have had time to expand with temperature.
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      11-01-2012, 05:29 PM   #8
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Quote:
Originally Posted by Route 16 View Post
Who was your Bay Area tech for the 3stage intake manifold install? How often do you do all the regular maintainance since you've had the car?
I have a guy works on my car on the side. I do oil changes every 7500ish miles, plugs, tranny and diff at 60k, everything else when it breaks or wears out.
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      11-01-2012, 06:43 PM   #9
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Quote:
Originally Posted by e90pilot View Post
I have a guy works on my car on the side. I do oil changes every 7500ish miles, plugs, tranny and diff at 60k, everything else when it breaks or wears out.
Care to share his skills by PM? And those 3 changes every 60k or you have a list? I'd like to run it as long as you.
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      11-01-2012, 08:01 PM   #10
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Quote:
Originally Posted by e90pilot View Post
I have a guy works on my car on the side. I do oil changes every 7500ish miles, plugs, tranny and diff at 60k, everything else when it breaks or wears out.
Quote:
Originally Posted by Route 16 View Post
Care to share his skills by PM? And those 3 changes every 60k or you have a list? I'd like to run it as long as you.
+1

I need some stuff done to my car soon, let me know since were all local!
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      11-01-2012, 08:49 PM   #11
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I was trying to think what I do regularly. It's just fluids and plugs. Everything else I just wait for it to wear out or the car tells me I need a new one (like the cabin air filter). The one thing I'm in the dark about is the engine air filter. I don't know when in the BMW service plan I was changed. I just know I change it when I put the Performance intake on and haven't cleaned or changed it since. It's probably due for a change/cleaning.

The trick to getting it to run a long time is driving the car. Just from what I've seen in the forums and what BMW techs tell me, the worst thing you cans do to it is let it sit or short commutes (less than ten min). Also, driving it too gently can caus issues as well. Every week the engine needs to see redline (after reaching full operating temp of course). It was designed to run hard, not to be mistaken with abuse. Keep it below 3k rpm and 1/3 throttle until at least 10 min of driving. Don't slam the shifter around, ride the clutch, or buck on and off the mounts. I'm on almost the original clutch (replaced at 8k mi due to cracked pressure plate) and original engine/tranny mounts.

The other thing is, you know your car intimately, especially if you've driven it almost 200k. You know every sound it makes, how the shifter, the clutch and brakes feel, every quirk it has since you've owned it. Listen to your car. It talks to you. If something feels off, something is usually wrong or maybe it's just wearing normally and needs replacement. Regular maintenance isn't enough on an old car. Don't let things get so bad to the point where driving the car becomes impossible or unsafe.

As for sharing my mechanic, I probably can't. He does side jobs for me and its kinda on the DL.
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