E-Class (W124) 1984-1995: E 260, E 300, E 320, E 420, E 500 (Includes CE, T, TD models)

M103 compression specs

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Old Aug 16, 2007 | 09:02 AM
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From: Northwest NJ
'90 300E Blk/Tan
M103 compression specs

Can anyone tell me the compression numbers I should be seeing on the M103 engine in my 90 300E ? 3.0L SOHC
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Old Aug 16, 2007 | 02:02 PM
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From: REHOBOTH BEACH DE
88-300CE TWIN TURBO, 99-C43, 05-G55K, 71-280SL, 94-E320 CAB, 08 CLK63 BLACK SERIES
Originally Posted by Andy_M
Can anyone tell me the compression numbers I should be seeing on the M103 engine in my 90 300E ? 3.0L SOHC
Not as much the actual number in each cylinder, but the difference between cylinders.

Not sure if MB published a range like they did for the four cylinders ( 147-176PSI ), but they indicate a minimum of 8.5 bar / 125PSI with a max variance between cylinders of 1.5 bar / 22.0PSI.

Prior to my turbo install we had 12.9 bar / 190 PSI with less then a 5 PSI variance betwen cylinders.
This was on a well maintained 1988 M103-12V with 63K miles.
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Old Aug 16, 2007 | 02:30 PM
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From: Northwest NJ
'90 300E Blk/Tan
Good. I'm getting 190psi +/- 5 psi. on all but the cylinder that I believe has a burnt valve. Not to shabby for 125k miles......
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Old Aug 16, 2007 | 02:33 PM
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From: REHOBOTH BEACH DE
88-300CE TWIN TURBO, 99-C43, 05-G55K, 71-280SL, 94-E320 CAB, 08 CLK63 BLACK SERIES
Originally Posted by Andy_M
Good. I'm getting 190psi +/- 5 psi. on all but the cylinder that I believe has a burnt valve. Not to shabby for 125k miles......
Excellent !!!
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