Compression Test Numbers

[MSP2k3]

I have searched and found that normal compression test numbers for a stock internal MSP engine is around 175-180...

Well, i did a compression test on my car tonight and got 205-205-200-200... Im not sure what to think of it. I have heard that if you have carbon build up on the pistons that it can raise your compression numbers? They were all close to each other so i guess that is good.

I removed all the spark plugs, held the throttle wide open and turned the engine over 4-5 times until the gauge stopped moving.

any ideas?

 

[ForceFed]

I would say its an error with the gauge...They are plenty close together.

Was this a Dry test or Wet?

 

[MSP2k3]

It was a dry test, but the car was warmed up to normal operating temps. The numbers were so high i figured i didn't need to drop any oil in and retest. I just bought the gauge before i did the test. I guess i don't need to worry since they were so close together.

 

[BOOSTR]

Exactly the actual number is not as important as the differences between lowest-highest readings and between cylinders. Exception to that would be extremely low readings. You appear to have an otherwise healthy engine.

 

[MSP2k3]

Awesome, thats what i was hoping for.. good to know =)

 

[XoX1de]

your gauge adapter can make a good difference , i used a 6 inch tube extender i got 130psi, when i removed the extender i got 200

 

[spicyprotevo]

I did mine a couple weeks ago, and I knew I needed a rebuild, but I was very suprised. I'm in Utah, so my numbers are going to be WAY low compared to yours, but all of my cylinders were about 160 psi, wet. Except cylinder #3. It was at 130. Just barely above the factory spec (125ish?). So, it's time for a rebuild.

 

[MSP2k3]

I did mine a couple weeks ago, and I knew I needed a rebuild, but I was very suprised. I'm in Utah, so my numbers are going to be WAY low compared to yours, but all of my cylinders were about 160 psi, wet. Except cylinder #3. It was at 130. Just barely above the factory spec (125ish?). So, it's time for a rebuild.

Yeah, its not good if 1 cylinder varies that much from the other 3

 

[BOOSTR]

I have heard that if you have carbon build up on the pistons that it can raise your compression numbers?

Missed this yesterday but you should make a habit of topcleaning or decarboning your engine by pouring seafoam slowly through your pcv hose, goose the throttle while doing it and shut the car off for a few minutes. If its really bad you might want to do it twice or let it soak longer. Put the rest in your gas tank when you fill up. I do the treatment all of time and have no carbon issues, dipping rpms, vacuum issues, dirty injectors or EGR issues.

 

[MSP2k3]

Missed this yesterday but you should make a habit of topcleaning or decarboning your engine by pouring seafoam slowly through your pcv hose, goose the throttle while doing it and shut the car off for a few minutes. If its really bad you might want to do it twice or let it soak longer. Put the rest in your gas tank when you fill up. I do the treatment all of time and have no carbon issues, dipping rpms, vacuum issues, dirty injectors or EGR issues.

Have been planning to do that but have procrastinated since i do not have any of the issues that you listed. Car runs great, but wanted to do a compression test for peace of mind. Thanks again for the help

 

[BOOSTR]

I do it frequently and have for a long time. The last treatment just for s**** & giggles I did it twice and let the 2nd treatment sit overnight.

 

[R-X-R]

maybe u r the lucky one to have to high compression engine that rolled out from the factory.,,,lol