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  #1  
Old 01-14-2003, 09:52 PM
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1972 280se oil pressure

1972 2.8L engine is barely above 0 when idling in drive when warm. When it shifts to its final gear it is at about at 25-30 at 55 mph. Is this okay? The engine runs strong and does not knock or smoke.
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Old 01-15-2003, 12:39 AM
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When I got my '72 250 (M130-2.8L) 15 years ago, the oil guage read about 6 PSI at hot idle and struggled to make 35 PSI at road speeds. The previous owner had run it low on oil. When revved up, in neutral with the door open, rattlng sounds from the engine could be heard. I wound up dropping in a used engine.
Today, 80,000 miles later, it still reads about 20 PSI hot idle (in drive) and pegs the guage at much above idle speed. Your readings don't sound good. I've found the factory VDO mechanical oil pressure guages to be pretty reliable, but checking it out with an oil pressure testing guage (if you can get the correct adapter) would be a good idea, before condemming the engine.

Happy Motoring, Mark
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Old 01-15-2003, 10:48 PM
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According to a mecanical friend of mine, the oil pressure is a fonction of the oil pump not to the fact that the engine is good or not. But if the pump is "week" then the engine will surely suffer in the long run.
Having said that, I'm no expert.....
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Old 01-16-2003, 12:13 AM
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Assuming your oil guage is accurate, a bad oil pump or stuck oil pressure relief valve could cause low oil pressure. Usually low oil pressure is due to bad/worn engine bearings.

Happy Motoring, Mark
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Old 01-16-2003, 01:23 PM
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Quote:
Originally posted by Mark DiSilvestro
Usually low oil pressure is due to bad/worn engine bearings.

Happy Motoring, Mark
Thanks Mark, I forgot about that, I'll stik with what I know.........If you put it in drive and it go's forward, it's OK
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  #6  
Old 01-18-2003, 05:06 PM
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Once had a '63 190d (gasoline) with similar symptoms... but engine racket told me it was piston wrist pins and/or connecting rod bearings.

If your engine is making no noise, then oil pump gears might be worn down.... leaving too much space between gears to drive oil pressure. I've heard of older oil pumps going soft.

One guy told me that low oil pressure idling at/near 10 psi is not as important as how quickly oil pressure rises on tapping the accelerator.
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Old 01-18-2003, 07:10 PM
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Clunker,

You only need a few pounds of oil pressure to supply the oil to the plain bearings in the bottom end, and it should be enough to lift the oil to the valve cover area.

when an engine wears, the clearances get larger and your oil pressure can drop.

As long as you have some pressure, your engine will continue to live.

I wouldn't stress it out too much in its old age. Treat her like a lady!
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Old 01-19-2003, 05:44 AM
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Something to consider for the Summertime...... Harley Davidson shops sell straight weight engine oils.... 30, 40, 50 weight

You might get better oil pressure with straight weight 40 than with 10-40 multigrade blend.

Hell, the old engine might even thrive on straight 50 wgt if you live in hot climate like Arizona.
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