7.3L Compression test: questions?????
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
7.3L Compression test: questions?????
I posted a few weeks ago about this truck (7.3L No Start) and that owner has since sold the truck but it seems to be following me wherever I go 
.
So the current owner comes over today and says, "I want you to
change the injector o-rings in this truck, I'm sure that is causing the smoke".
So I told him how much it would cost him to change the o-rings and I also said that because of other symptoms that I have run into while working on the truck before, that I would reccomend doing a compression test.
He said, "When can I bring it over" So he is bringing it to me on friday morning.
My main question is: How do I find something to go in the glow plug hole to hook up to the compression gauge?
Any help or pointers would be greatly appreciated!
P.S. I guess I should give you all the symptoms.
Excessive smoke at startup, followed by a light haze while driving, moderate blowby, with a little pressure out of the filler neck.
It also does not start as quickly as it should. It takes about 50% more cranking time to start than a solid Powerstroke does.
.So the current owner comes over today and says, "I want you to
change the injector o-rings in this truck, I'm sure that is causing the smoke".
So I told him how much it would cost him to change the o-rings and I also said that because of other symptoms that I have run into while working on the truck before, that I would reccomend doing a compression test.
He said, "When can I bring it over" So he is bringing it to me on friday morning.
My main question is: How do I find something to go in the glow plug hole to hook up to the compression gauge?
Any help or pointers would be greatly appreciated!
P.S. I guess I should give you all the symptoms.
Excessive smoke at startup, followed by a light haze while driving, moderate blowby, with a little pressure out of the filler neck.
It also does not start as quickly as it should. It takes about 50% more cranking time to start than a solid Powerstroke does.
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
I read that compression should be 26-440 Psi. Is that correct?
And if the compression is low, are there any alternatives to replacing/rebuilding?
The truck has 157,000 miles on it.
Posting Guru
Joined: Nov 2007
Posts: 2,014
Likes: 1
From: Long Island, NY
From what I have heard 157k is nothing for our trucks. If the compression is not within specs with 157 on it some thing is very wrong like maybe coolant getting into the oil.
Trending Topics
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
Edit: 260-440psi. sorry my mistake.
157,000 miles should be just getting broken in, but this one seems like maybe it has had very poor if any maintanance.
I also think it has a chip in it, so that could be contributing to premature wear.
Is it possible that there chould be a bent push rod? will I be able to see it when I have the valve covers off?
Thanks guys, the help is greatly appreciated!!
157,000 miles should be just getting broken in, but this one seems like maybe it has had very poor if any maintanance.
I also think it has a chip in it, so that could be contributing to premature wear.
Is it possible that there chould be a bent push rod? will I be able to see it when I have the valve covers off?
Thanks guys, the help is greatly appreciated!!
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Compression should be 400 plus or minus 10%. Might be lower but you are mainly looking for close to 400 or all cylinders being within 10% of each other. You symptoms list certainly points at a compression issue.
The adapter in that picture is what I use with my compression tested but a GP can be adapted as well.
The adapter in that picture is what I use with my compression tested but a GP can be adapted as well.
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
Thanks everbody,
I just ordered injector o-rings from Jim at rosewood diesel (I know that this is probably not the problem, but the customer wants me to change them)
That sounds more ligitimate than 260-440psi. Thanks Tim!
If he has low compression in 1 cyl. which is what I suspect, (no.7) is there any alternative to rebuilding?
Thanks again,
I just ordered injector o-rings from Jim at rosewood diesel (I know that this is probably not the problem, but the customer wants me to change them)
Compression should be 400 plus or minus 10%. Might be lower but you are mainly looking for close to 400 or all cylinders being within 10% of each other. You symptoms list certainly points at a compression issue.
The adapter in that picture is what I use with my compression tested but a GP can be adapted as well.
The adapter in that picture is what I use with my compression tested but a GP can be adapted as well.
If he has low compression in 1 cyl. which is what I suspect, (no.7) is there any alternative to rebuilding?
Thanks again,
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Thanks everbody,
I just ordered injector o-rings from Jim at rosewood diesel (I know that this is probably not the problem, but the customer wants me to change them)
That sounds more ligitimate than 260-440psi. Thanks Tim!
If he has low compression in 1 cyl. which is what I suspect, (no.7) is there any alternative to rebuilding?
Thanks again,
I just ordered injector o-rings from Jim at rosewood diesel (I know that this is probably not the problem, but the customer wants me to change them)
That sounds more ligitimate than 260-440psi. Thanks Tim!
If he has low compression in 1 cyl. which is what I suspect, (no.7) is there any alternative to rebuilding?
Thanks again,
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
Thanks for all the input.
I just ordered a compression tester that will work in the glow plug hole from my local napa store, it will arrive tommorow.
I will be posting with progress-more likely questions
!!! as I get into the project. The owner of this truck has another 7.3L (2002 4x4 CC SB Auto) that he claims has 380 horsepower with just a chip and a shift kit 
HAHAHA!!!! but, oh, I'm rambling.
My plan is to remove the VC and all of the other necassary parts, do a compression test, leak down test, etc.....
BTW, excuse my ignorance, but does anyone have any info on doing the leakdown test???
I just ordered a compression tester that will work in the glow plug hole from my local napa store, it will arrive tommorow.
I will be posting with progress-more likely questions
!!! as I get into the project. The owner of this truck has another 7.3L (2002 4x4 CC SB Auto) that he claims has 380 horsepower with just a chip and a shift kit HAHAHA!!!! but, oh, I'm rambling.My plan is to remove the VC and all of the other necassary parts, do a compression test, leak down test, etc.....
BTW, excuse my ignorance, but does anyone have any info on doing the leakdown test???