Compression Test
Thread Starter
|
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
Compression Test
I think I'm going to get some free time so I'm going to do a compression check, then pull my broken up pipe out to repair it. What is the proper procedure for doing the test? Pretty tough to do on a warm engine, isn't it? Also, do you pull all the GP's out or one at a time? Any tips and tricks, thanks!!
Hotshot
Joined: Dec 2005
Posts: 14,375
Likes: 604
From: evansville in
Get it warm and then plug it in..that will at least keep it somewhat warm. I would pull them all.just what ever you do do it thesame way throughout. Either all but one being tested or all out. Consisnant is the name of the game. Good to hear you are moving forward sir.
Thread Starter
|
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
Thanks Aaron, should I pull fuse 20 or is it 22 so it doesn't try to start? Or just un plug the uvch plugs? I don't want to flood the cylinders with fuel. Then again, with all the GP's out I shouldn't need to worry about starting or flooding I wouldn't think.
Logistics Pro
Joined: Jul 2001
Posts: 4,137
Likes: 41
From: Marble Falls, Texas
Glenn, when I do it, I remove the valve covers and gaskets with the UVC's. This way no wiring gets pinched or anything while your in there. So no start, no flood.
Pulling all 8 gp's at the same time helps your starter be happy. Since you are gonna be cranking on it a lot, say 5 or so revolutions per cylinder. It just saves battery and starter with no compression on all the other cylinders.
Pulling all 8 gp's at the same time helps your starter be happy. Since you are gonna be cranking on it a lot, say 5 or so revolutions per cylinder. It just saves battery and starter with no compression on all the other cylinders.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
If it's anything like a compression test on a gasser, you always want to remove all the glow plugs. That will cause the starter to turn the engine at a higher and constant speed, for a more accurate compression reading.
I would just pull fuse #22; no point in risking damaging the UVCH connector tab/clip thingies. And you want to pull it anyway; if you leave it connected, it'll send 110VDC down the injector wires, and if those somehow ground out, or if you get between it and ground, might not be good.
I would just pull fuse #22; no point in risking damaging the UVCH connector tab/clip thingies. And you want to pull it anyway; if you leave it connected, it'll send 110VDC down the injector wires, and if those somehow ground out, or if you get between it and ground, might not be good.
Hotshot
Joined: Feb 2009
Posts: 10,408
Likes: 75
From: Plankinton, SD
Trending Topics
Lead Driver
Joined: Mar 2006
Posts: 5,098
Likes: 1,504
From: western SD
When we checked the compression on my sons 99, I left the key in the off position, and jumped the starter relay with a screw driver. No juice to the computer, and no going back and forth to the ignition switch. How much difference in compression between a warm engine and a cold one?
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
Thread Starter
|
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
I was thinking about using the starter relay Tom.
Jim, your a funny man!! LOL I just have to take the up pipes out to be fixed so why not? Its something I should have done last year before I poured thousands into mods. Of course, if its low on compression I will go into a deep, deep depression that will last for awhile, LOL.
I'll have to get some of Bill's pain pills, if he's not using them, so I can sleep at night! LOL
Jim, your a funny man!! LOL I just have to take the up pipes out to be fixed so why not? Its something I should have done last year before I poured thousands into mods. Of course, if its low on compression I will go into a deep, deep depression that will last for awhile, LOL.
I'll have to get some of Bill's pain pills, if he's not using them, so I can sleep at night! LOL
Senior User
Joined: Sep 2013
Posts: 184
Likes: 0
From: Durham NC
I borrowed a compression gage from a friend that works on Powerstrokes for a living
Pull all GP's......The compression tester is like a GP, make sure you do not loose the small o-ring that goes on the part that screws into the GP hole.
I think he told me all should be with 10-15 lbs of each other and a good engine should run from 400-425 psi
I maybe wrong about the 400-425 number...I will have to go back to the post I made here when I was doing this test.......When my turbo ate my DuraLite air filter and destroyed my turbo wheel
Pull all GP's......The compression tester is like a GP, make sure you do not loose the small o-ring that goes on the part that screws into the GP hole.
I think he told me all should be with 10-15 lbs of each other and a good engine should run from 400-425 psi
I maybe wrong about the 400-425 number...I will have to go back to the post I made here when I was doing this test.......When my turbo ate my DuraLite air filter and destroyed my turbo wheel
Lead Driver
Joined: Oct 2010
Posts: 5,128
Likes: 44
From: Columbus, Oh
So this is my theory and just a theory so take it for that. How would pulling all the GP's net you a more accurate reading? The motor doesn't operate with them out. Wouldn't true compression under operating conditions, be achieved one at a time? Don't crucify me if I'm way off base here.
Hotshot
Joined: Feb 2009
Posts: 10,408
Likes: 75
From: Plankinton, SD
So this is my theory and just a theory so take it for that. How would pulling all the GP's net you a more accurate reading? The motor doesn't operate with them out. Wouldn't true compression under operating conditions, be achieved one at a time? Don't crucify me if I'm way off base here.
Thread Starter
|
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
Well today was a flop. I couldn't get the make shift compression grease whip M10 x 1.0 combo to work. It keeps hitting the rocker and push rod, even after grinding it down some. I took the M10 x 1.0 fitting off and put it on a rubber hose and it will thread right into the GP hole, no problem. But when attached to the grease whip it will start then bind. Tried it on #1 & #3 hole. 
