Jeff,

No argument. Consider, however, that the engine is lubricated by 10W40
weight oil. When cold the oil is 10W (mas o menos) and loose rod bearings
would not hold pressure well if at all. When the engine is at operating
temperature the lubricating oil is 40W or so. It's difficult for me to
visualize an engine with 10W at idle cold having pressure much higher than
the same engine with 40W hot at 3800 RPM.

Seems to me the rods would be banging like the devil at virtually any RPM.
My experience with engines is that it is very rare for all rod bearings to
fail together. It is almost always one bad bearing. I guess an exception
would be when the engine is operated with a very low oil level but that
would also destroy crankshaft and cam bearings, no?

Thanks.

Butch
"Jeff Rigby" wrote in message
...

"Butch Davis" wrote in message
ink.net...
Far more likely, IMO, is an instrumentation issue. If the clearances in
your engine were so worn as to cause an oil pressure loss when hot with
10W40 oil you'd not have pressure when starting. As engine speed
increases the oil pump output increases. A relief valve keeps the
pressure from going too high. No offense Jim but you clearly know very
little about engines. Better no reply than a totally unfounded reply.

Butch, at first thought you would think the oil pressure would increse as
RPM increases but rod bearings when very bad SLING oil. Like if you
(after priming) sling a hose around your head it will pump water out of
the hose. This causes a loss of oil pressure! Very bad engines can have
15 pounds of oil pressure at idle and that will drop when you accelerate
the throttle. I've read about it and finally saw it recently. Usually
it's also very noisy.

I'd certanly check oil pressure with a mechanical gage if the engine is
not noisy. If oil pressure is low I'd pull the pan and check clearances
on the bearings and if good suspect a slipping shaft to the oil pump.

Butch
"Jim Goodall" wrote in message
...
I'd be checking the crankshaft and rod bearings. Sounds like when
things get hot, clearances get large and simply let all the oil flow
freely out of the bearings, as the crank is spinning on a layer of oil,
within the bearings. It won't be long before you spin a bearing and
ruin the crankshaft.
Jim

josZ wrote:

The oil pressure in my engine, a volvo penta 3.0gs from 1996, is gone
above 3800 when the engine is hot. I use multigrade 10w40 oil. What
could be the problem?

thanks in advance Jos


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