help confirming diagnosis?

[brrrnntsshhhh]

I just did a compression test and cylinder 4 runs 175, the rest of them run 145. My motor has 217k miles so i figure the 145 would be normal wear and tear. Am I wrong? What should I do? It was rebuilt sometime before i bought the car at 180k. but i dont know why one would have really good compresssion and the rest would be low.
I think it is my headgasket because i was blowing smoke, sort of a whitish grey color - but i was running a bit rich also on 880cc injectors with dsm link. I did look in my coolant and dipstick and very hard to tell if there is any oil in the coolant or vice versa, are there easier ways of teling?

Also my valve cover gasket was leaking oil onto cyl 4 which could have caused the smoke. I fixed this problem. IM also doing the rear motor mount and have started doing the timing belt, I was wondering if it was worth putting back together to let it run and see if it still smokes?

plug on cyl1 looks a bit rusted like maybe coolant was in there or something. ideas? confirmations?

thanks for your time,
troy

 

[MrBoxx]

The smoke could be a combination of the oil and running rich, but just to be on the safe side, I would check for turbo shaft play. A failing turbo seal sometimes causes white-gray smoke to poof out after shifts.

 

[brrrnntsshhhh]

so what should i do about the compression, is that fine?

 

[96gsdsm]

The compression most likely is due to the leaking oil into cyclinder 4 ... get that leak fixed, then re-test.

My guess is that the pressure in cycl. 4 is rising MUCH quicker then 1, 2 & 3

or.... maby the engine threw the #4 piston/rod and the "rebuild" that the previous owner did at 180k only included rings on the #4 piston

now remember your car has 37k on a new rebuild ... If it was done properly it shouldn't be smoking PERIOD ... with the exception of a possible blown turbo as mrboxx stated

 

[96gsdsm]

so what should i do about the compression, is that fine?

The answer is tecnically... yes, your cyclinders' compression should be withen a 25% limit of each other..... right now your only 6.25% away from the full 25% so your just squeaking it

My recomendation is trying your best to get that #4 cyclinders compression to come down ... even though on paper it's fine

Hope all that helped

 

[Splitpi]

From the Service Manual on Compression to be in spec:
Standard: 178 Psi
Minimum: 133 Psi
Variance: 14 Psi from any two cyclinders.

 

[96gsdsm]

From the Service Manual on Compression to be in spec:
Standard: 178 Psi
Minimum: 133 Psi
Variance: 14 Psi from any two cyclinders.

Whoops, I do believe i gave you 420A specs.

 

[xveganxcowboyx]

Maybe that cylinder ran rich for a while and formed deposits.

 

[oldman]

96gsdsm, we are all here to participate but please post only if you're 100% sure.

brrrnntsshhhh, I would repeat the test again with car fully warmed up, battery fully charged and throttle fully applied then immediately follow it up with a wet test.