Compression Test
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Registered User
Joined: Feb 2015
Posts: 11
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From: Hollywood, CA
Compression Test
Hey all,
Let me preface this by saying it was my first time ever doing this. So bare with me.
After some recent developments I have found that Im leaking coolant out of the front of the engine. (Guessing its water pump or something related, but ANYWAYS...) I jumped down the rabbit hole of worry thinking I might have a crack in the block or heads or something worse than the intake gasket sucking from a bad plenum. I also recently got the oil changed and noticed gas smell in the oil for the past week... even after 20 mile highway commutes to and from work. (figured it would burn off, it hasn't; injector maybe?) To get back on topic and make a long story, semi-long: I figured I should single out the problem and make sure the truck can still produce compression. (it is a little sluggish at lower RPMs and tends to ping when I floor it.)
I did a Compression test:
Warmed up truck
pulled plugs and get to work.
results are in the attached picture. I am illiterate of the cylinder order so I just made a diagram.
The Good:
1. consistency? No?
2. small differences on dry and wet tests
3. No cracks?
4. my truck can compress like a mofu!
not sure thats good though...
The Bad:
1.) biggest concern is that my compression is way higher than I have ever seen any of the tests on youtube or some of the threads 190psi highest!
2.) concern is that one side is less that the other. Lowest is about 10% 170:190
3.) I smelt a lot of gas by the end of the testing.
4.) my CEL is now on.
The Ugly:
1. I still have a coolant leak
2. I still need to repair the plenum.
Let me know if you have an opinion, good, bad, or ugly.
I can take it.
Let me preface this by saying it was my first time ever doing this. So bare with me.
After some recent developments I have found that Im leaking coolant out of the front of the engine. (Guessing its water pump or something related, but ANYWAYS...) I jumped down the rabbit hole of worry thinking I might have a crack in the block or heads or something worse than the intake gasket sucking from a bad plenum. I also recently got the oil changed and noticed gas smell in the oil for the past week... even after 20 mile highway commutes to and from work. (figured it would burn off, it hasn't; injector maybe?) To get back on topic and make a long story, semi-long: I figured I should single out the problem and make sure the truck can still produce compression. (it is a little sluggish at lower RPMs and tends to ping when I floor it.)
I did a Compression test:
Warmed up truck
pulled plugs and get to work.
results are in the attached picture. I am illiterate of the cylinder order so I just made a diagram.
The Good:
1. consistency? No?
2. small differences on dry and wet tests
3. No cracks?
4. my truck can compress like a mofu!
not sure thats good though...The Bad:
1.) biggest concern is that my compression is way higher than I have ever seen any of the tests on youtube or some of the threads 190psi highest!
2.) concern is that one side is less that the other. Lowest is about 10% 170:190
3.) I smelt a lot of gas by the end of the testing.
4.) my CEL is now on.
The Ugly:
1. I still have a coolant leak
2. I still need to repair the plenum.
Let me know if you have an opinion, good, bad, or ugly.
I can take it.
Last edited by GoDak; Feb 18, 2015 at 03:31 AM.
Thread Starter
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Registered User
Joined: Feb 2015
Posts: 11
Likes: 0
From: Hollywood, CA
How To Perform a Compression Test - EricTheCarGuy - YouTube
This guy is pretty good, He makes things easy to understand and his website forum is helpful as well. They gave me some important real time help when I did the plenum kit & timing chain/tensioner on my Dak.
This guy is pretty good, He makes things easy to understand and his website forum is helpful as well. They gave me some important real time help when I did the plenum kit & timing chain/tensioner on my Dak.
I performed the test and have the results on that attached picture.
Thanks for the response, I will check out his forum.
All Star
Joined: Apr 2013
Posts: 941
Likes: 22
From: Connecticut
I wouldn't worry about the compression numbers. That looks very good. You may have a high reading gauge, but what matters most is the variances between cylinders and banks. 10% variance is fine. Very fine. I just sold a guy a Subaru motor (H6) that had 180psi at the high end and somewhere in the high 130s at the low (yes I told him this)...and you never could have guessed when it was running because it ran and drove great.
