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Discussion Starter · #1 ·
Hi
I have just rebuilt a 2008 engine, it starts but sounds like a bag of spanners. I changes the bottom half of the cylinder, hit a curb.

I have done a compression test and do not understand the results, can someone help?


Cylinder 1 - 150 with oil in the cylinder 153
Cylinder 2 - 149 with oil in the cylinder 153
Cylinder 3 - 151 with oil in the cylinder 175
Cylinder 4 - 176 with oil in the cylinder 200


Why is one so high? surely a bad cylinder should have low compression?

Or do I have three bad cylinder and one good one??

Any help would be great.

Kind regards
Mark
 

· Registered
Joined
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13,577 Posts
Hi
I have just rebuilt a 2008 engine, it starts but sounds like a bag of spanners. I changes the bottom half of the cylinder, hit a curb.

I have done a compression test and do not understand the results, can someone help?


Cylinder 1 - 150 with oil in the cylinder 153
Cylinder 2 - 149 with oil in the cylinder 153
Cylinder 3 - 151 with oil in the cylinder 175
Cylinder 4 - 176 with oil in the cylinder 200


Why is one so high? surely a bad cylinder should have low compression?

Or do I have three bad cylinder and one good one??

Any help would be great.

Kind regards
Mark
which order did you do the test state of battery could make a difference ie how fast engine cranks over, also were all plugs out before starting compression test, i if some plugs let in when cranking will cause extra drag slow crank down, maybe valve springs gone weak or timing chain worn
 

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2003 R53 Liquid Yellow and 2012 R58 Coupe Cosmos black
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144 Posts
Looking at those readings I would suspect that the head gasket is bad.
Readings should be within 10% of each other without oil.
Two or more adjacent cylinders with low compression suggests a compression leak through the head gasket between cylinders

Gerry
 
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