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Author Topic: Compression values PSI  (Read 2359 times)

Benz280

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Compression values PSI
« on: March 14, 2022, 22:12:44 »
The topic of compression is all over the board re 230 vs. 250 vs 280.
For the record, what is considered prefect and then acceptable ? 
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1971 280SL 4 Speed
1995 E320 Cab
1965 Shelby GT350

Benz Dr.

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Re: Compression values PSI
« Reply #1 on: March 15, 2022, 05:53:20 »
Somewhere in the 170 - 180 PSI for 280 and 250 is optimal. 230 can be as low as 150 PSI with stepped pistons or about 165 PSI with flat top type. MB will tell you a 10 - 15% loss is already rebuild time but a 280 will still run OK at 140 PSI. When you get down to 120 PSI you will have problems with hard starting and probably oil smoke.
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1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Cole

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Re: Compression values PSI
« Reply #2 on: July 17, 2023, 01:13:19 »
Hi,

The compression test on my 250SL yesterday was:
Cylinder 1 - 170
Cylinder 2 - 170
Cylinder 3 - 165
Cylinder 4 - 170
Cylinder 5 - 170
Cylinder 6 - 175

On the the 280SLs and 250SLs, what was the compression when they left the factory?

Thanks!
Cole
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Cole
'69 280SL, 40G Black/Burgundy Interior
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