Compression Problem
Thread Starter
Racer
Joined: Jul 2000
Posts: 365
Likes: 0
From: Flippin AR
Compression Problem
Changed all eight spark plugs yesterday to NGK Iridium plugs. With 19k miles on my 2000, the OEM plugs looked like new. No wear, and just minor discoloration. Very impressive.
I performed a compression check while the plugs were out. Used a screw driver handle to hold open the throttle plate. Had these results:
PSI Hole PSI
175 1 2 180
150 3 4 180
180 5 6 178
175 7 8 175
While the manual states that anything above 100 PSI is fine, and the lowest must be within 70% of the highest, I am very concerned with the 150 PSI reading on the #3 hole. It is 18% below the others.
Yes, I checked, rechecked, changed the o-ring on my compression tester, checked other holes, rechecked the #3, and it's 150.
Does anyone know if there is any valve cleaning type of snake oil that might clean the valve faces before the #3 burns any further?
Should be concerned about this?
I performed a compression check while the plugs were out. Used a screw driver handle to hold open the throttle plate. Had these results:
PSI Hole PSI
175 1 2 180
150 3 4 180
180 5 6 178
175 7 8 175
While the manual states that anything above 100 PSI is fine, and the lowest must be within 70% of the highest, I am very concerned with the 150 PSI reading on the #3 hole. It is 18% below the others.
Yes, I checked, rechecked, changed the o-ring on my compression tester, checked other holes, rechecked the #3, and it's 150.
Does anyone know if there is any valve cleaning type of snake oil that might clean the valve faces before the #3 burns any further?
Should be concerned about this?
Melting Slicks
Joined: Aug 2000
Posts: 2,248
Likes: 1
From: Newland US
Re: Compression Problem (John Silver)
John Silver,
Good looking numbers.....except for #3. Did you do the compression test on a warm engine?
Also did you squirt a little oil intp #3 and retest the compression to see if it came up which would indicate a ring problem. If the reading remains the same, that indicates a valve problem.
A leak down test could be a little more specific on diagnosing the problem.
Good luck and let us know what ya find.
Mark
Good looking numbers.....except for #3. Did you do the compression test on a warm engine?
Also did you squirt a little oil intp #3 and retest the compression to see if it came up which would indicate a ring problem. If the reading remains the same, that indicates a valve problem.
A leak down test could be a little more specific on diagnosing the problem.
Good luck and let us know what ya find.
Mark
Thread Starter
Racer
Joined: Jul 2000
Posts: 365
Likes: 0
From: Flippin AR
Re: Compression Problem (MDT)
Mark, the engine was stone cold. I thought about using the oil trick but I just couldn't bring myself to believe it could be a ring problem. For my sanity, I have to believe a valve seat is a bit dirty. Unfortunately I don't have leak down equipment, and I don't think the dealer will touch it while it's within specs.
Melting Slicks
Joined: Aug 2000
Posts: 2,248
Likes: 1
From: Newland US
Re: Compression Problem (John Silver)
John,
Just for the heck of it, why not take another reading on #3 with the engine warm. Might not hurt to break the plug loose before warming the engine up....removing them hot from an aluminum head isn't a good idea. If it feels like it is binding, then I'd let her cool a bit and try again.
Good luck.
Mark
PS Meant to add that I don't think you have any thing to worry about. Your variation is well within the acceptable range.
[Modified by MDT, 7:51 PM 9/26/2001]
Just for the heck of it, why not take another reading on #3 with the engine warm. Might not hurt to break the plug loose before warming the engine up....removing them hot from an aluminum head isn't a good idea. If it feels like it is binding, then I'd let her cool a bit and try again.
Good luck.
Mark
PS Meant to add that I don't think you have any thing to worry about. Your variation is well within the acceptable range.
[Modified by MDT, 7:51 PM 9/26/2001]
