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<--before leveler & block
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852 Posts
Discussion Starter #1
:doh: :doh: :doh: Well it wasn't as good as i would hoped but here they are:

1-330psi
2-340psi
3-300psi
4-300psi
5-340psi
6-330psi
7-300psi
8-320psi

These are not so great from my understanding. They all seem somewhat close to each other though and the truck runs great and blowby is just a little haze that spills out of the tube not blowing out of the tube. Blowby is not bad whatsoever.

I could this be some inaccuracy of my $30 compression gauge? If not then it must be valves?

Also there was no LL injector in #8 or anywhere else.

I am kinda bummed out to say the least
 

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Going Crazy
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1,533 Posts
Thats pretty low man.... was the motor warm or cold when you did these?
 

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<--before leveler & block
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852 Posts
Discussion Starter #3
It was cold when i did this test. The engine also has 140k on it but seems to run like a champ and barley burns any oil. Oil change every 4k and i fill it up to the max level and at the end of the 4k its down to the lower end of the crosshatching on the dipstick. I guess i will be looking at a rebuild this summer. Or maybe it just needs head work? might as well do a complete rebuild i guess :shrug:
 

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The Oracle
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2,777 Posts
i just read your other thread and if thats the compression tester you used i would DEFINATLY find another one to get a second reading....not to say its definatly wrong but you get what you pay for with tools
 

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Going Crazy
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1,533 Posts
i second using another compression tester... i used my buddies harbor freight one once then checked with my dads nice one and there was a pretty good difference......
 

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<--before leveler & block
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852 Posts
Discussion Starter #7
yeah i know you do especially with that type of a tool. I hope its the gauge and not my engine. My blowby is nothing to worry about and i can barely feel the exhaust coming out of the pipe at idle other than it just feeling warm. I wouldn't doubt that my compression is lower now than it was when the truck was brand new but i never would have thought it was that low.

Guess it soundsl ike some of my problem is the gauge. I will see how well it does on a 15* cold start tomorrow morning with the brand new motorcraft glow plugs and see what i get.
 

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Going Crazy
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1,533 Posts
my truck with 180k and some blowby did well over 400 on even the worst cylinder so either you got some issues in the heads or the tester... but if its running good i would deffinatly check with another tester before tearing it apart
 

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<--before leveler & block
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852 Posts
Discussion Starter #9
yeah i agree on the better tester. Do you think it is necessary to get a complete tester or just a better gauge to put on these hoses and check valve?
 

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<--before leveler & block
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852 Posts
Discussion Starter #11
Ok will look into that. What are your guy's reasoning for thinking that the tester is part of the problem? Because its cheap for one right? Do my compression numbers tell that the tester could be inaccurate?

Thanks for your help so far its greatly appreciated :bow: ;)
 

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Body Type: MULE
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2,012 Posts
WHY fix it if it is not broken???

IF it runs fine, you say you dont have any blowby and its only at the bottom portion of the cross hatches after 4,000 miles....then WHY???

I personally would just drive it and be happy. Compression readings BLAH...LOL

Good thing is it doesnt look like you have any broken rings so just run the dog!
 

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Body Type: MULE
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2,012 Posts
It was cold when i did this test. The engine also has 140k on it but seems to run like a champ and barley burns any oil. Oil change every 4k and i fill it up to the max level and at the end of the 4k its down to the lower end of the crosshatching on the dipstick. I guess i will be looking at a rebuild this summer. Or maybe it just needs head work? might as well do a complete rebuild i guess :shrug:
These engines have keystone style rings....they expand somewhat when warm. A cold compression test will give you lower readings...

I have used $30 compression testers for along time and have never had an issue when compared to a Snap-on compression tester.
 

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2010 BOB Points Runner up
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2,300 Posts
WHY fix it if it is not broken???

IF it runs fine, you say you dont have any blowby and its only at the bottom portion of the cross hatches after 4,000 miles....then WHY???

I personally would just drive it and be happy. Compression readings BLAH...LOL

Good thing is it doesnt look like you have any broken rings so just run the dog!
Thats what I'm thinking, It would be completely differnet if you were looking at buying a truck and got to do a compression check on it first, or you were having some sort of issue with it. But it is what it is and it gets the job done. . .

-Michael
 

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<--before leveler & block
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852 Posts
Discussion Starter #15
You guys are right and i agree with you almost 100%. I just have plans to put 200/30% injectors in it in a couple months.

As for temperature, the blcok was somewhat warm but definitely had to be less than 80 degrees and the temp gauge on the instrument cluster was bottomed out pretty/ 1/8th inch under the C mark.

Not sure what temperature those rings start to expand at.
 

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Body Type: MULE
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2,012 Posts
275 degrees range and it should be pretty well fully expanded. They typically expand with cylinder heat.

Unless you doing a FULL BUILD on your engine, dont bother with rebuild!....unlesss you just really want to!
 

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<--before leveler & block
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852 Posts
Discussion Starter #17
nothing other than injectors, maybe valve springs and pushrods. looking for 400hp

How much does the compression differ between cold vs. warm?
 

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<--before leveler & block
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852 Posts
Discussion Starter #19
Remember you are testing at altitude and your numbers will be low compared to a test at sea level. With the engine good and warm your reading should be around 365-375 which is good to go up here in CO.
Oh ok well this is starting to sound a little better. The elevation that i am at is 6,600 ft. so i guess my compression isn't to bad except the cylinders that are reading 300psi. I never thought about the elevation
 

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The Oracle
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2,777 Posts
Remember you are testing at altitude and your numbers will be low compared to a test at sea level. With the engine good and warm your reading should be around 365-375 which is good to go up here in CO.
yupp he's right, i didnt realize you lived in the sky...dont worry about the "lower" numbers
 
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