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Old 11-05-2000, 11:44 PM
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Aaron Aaron is offline
Join Date: Aug 1999
Location: Cincinnati, Ohio
Posts: 1,935
The gauge will peg 3 bar just after startup and will remain there until the engine warms up and the oil thins out some. 1.5 bar is correct pressure at idle at normal operating temp. Some of the larger engines such as the M-100 (6.3, 6.9) and the M-120 (V-12) will idle with the needle around 1 bar or 15psi when warm and at idle. It's just characteristic of the big engines. As long as oil pressure rises immediately upon acceleration, you have nothing to worry about. Funny this thread came up, as I had a '75 450SL in the shop the other day with 283,000 miles on it and when I was on the freeway on the test drive, the oil pressure gauge didn't even peg full pressure at 70mph. I'd say the mill was just a little worn

By the way, you guys with 380s, 420s and 560s, I would strongly recommend "priming" the engine after an oil change. To do this, look on the driver's side inner fender well for a black box (the ICU) which will have a plug with a green wire connected to it. Pull the plug and crank the engine over for about 15 seconds then re-connect the plug and fire it up. This will get the oil pressure built up to avoid a "dry" start.

Aaron Greenberg
MB technician
Mercedes-Benz of Cincinnati
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'86 420SEL
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'84 BMW 745i Turbo

[This message has been edited by Aaron (edited 11-05-2000).]
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