Scott Fisher <sfisher@wsl.dec.com> sez:
|> Re: my high oil pressure.
|>
|> I don't mean to be a stickler, but remind me of things like how
|> fresh the bearings are, when the problem arose, etc. I can't
|> seem to find the original message on this subject. If, for instance,
|> you just put in 40-under bearings on a 20-under crank, we'd know
|> what the problem is... if the problem started recently on a well
|> used but still sound engine, that's another story entirely.
|>
The problem started somewhat recently on a well used but hopefully
sound engine. I'm not sure exactly when the problem arose. I think
the pressure has always been a little high since I bought the car a year
ago. A couple of weeks ago I installed the oil cooler that came with
the car. After installation I drove the car paying close attention to
the oil pressure to make sure everything was okay. This is when I noticed
the pressure was really high, pretty much pegged at 100 psi. I thought
the problem was something in the oil cooler, so I took it out. That
helped only slightly (and I think this was due to the fact that the oil
was getting hot faster.)
|> Last night I found the oil pressure relief valve. [. . .]
|> (i.e. will removing it drain the oil for me :-) ?
|>
|> No. It's above the level of the sump, so while you'll certainly get
|> some oil on the side of the block, there's no way you can drain the
|> oil unless you pull it while the car is running. However, for reasons
|> I will address shortly, it's probably a good idea to drain the oil
|> anyway.
|>
It looks like to get this out I'm going to have to move the exhaust
manifold. Hmmm, maybe this would be a good time to buy a header.
|> I am beginning to think there is a problem. With the oil cooler out, the
|> pressure is still too high until the engine is hot (I think the oil cooler
|> kept the oil cool and thus the pressure high.) I still haven't ruled out
|> a faulty pressure sensor, since it may have gotten banged up a little
|during
|> the installation of the oil cooler (detaching the old hose from the back of
|> the block was a b*tch!).
|>
|> Which kind of sensor do you have? It might be easier for you to test
|> the sending unit and gauge to make sure they're not feeding you false
|> information. Hook up a mechanical gauge with the right kind of
|> fitting -- I've got one in my garage (where is meaddata.com, anyway? :-)
|> It's the best way to determine whether you need a new engine or a new
|> gauge or sending unit.
The sending unit looks like a top with a little metal tab sticking out the
top. I swapped sending units last night. No change was apparent.
meaddata.com is in Dayton Ohio. Maybe I'll stop buy California on my
way back from Utah. I'm heading to mjb's Fat Chance Garage to get my
Weber tuned :-) I'll see if I can find one here, though.
|>
|> It's been my experience that MG engines are about fifty to a hundred
|> times more reliable than Lucas gauges. Chew on that thought while you
|> contemplate rebuilding your bottom end.
Well, considering my speedo reads high and my fuel gauge low, it wouldn't
knock me over with surprise if my oil gauge reads high.
|>
|> Assuming the pressure relief valve is bad, will I be able to get it out?
|>
|> The pressure relief valve is nothing more than a sort of bullet-shaped
|> plug of steel with a spring behind it and a bolt holding the spring
|> and bullet in the block. Basically, when you remove the bolt, the
|> spring will try to fly out of the block and get lost under your parts
|> car.
|>
|> How the PRV works: The spring holds the bullet against a restriction in
|> the oil passage. It only allows a certain amount of oil to flow through
|> the restriction, based on the amount of pressure that the spring applies
|> against the bullet. The typical failure mode is that the spring weakens
|> or breaks and there is insufficient pressure against the restriction.
|> This causes the gauge to read lower than normal. In the best of all
|> possible worlds, you're still getting oil flowing at the same volume
|> and you don't blow your crank into itty bitty pieces.
If it is stuck closed, it would seem to me that I won't be able to get it
to come out, since something besides spring tension is holding it in.
Doc Fisher's oil pressure relief RX deleted.
|>
|> BTW, I'm running Castrol 20W-50. I suppose I could switch to a lighter
|> oil but this seems like it would only treat the symptom.
|>
|> 20W-50 shouldn't be too high, unless it's really cold where you are.
It's not, it has been warmer than 50 since I noticed the problem.
|>
|> p.s. In the meantime it is just too nice out, so I've been driving it
|> anyway watching for an oil well to sprout in front of me.
|>
|> Keep the faith!
|>
I'm trying. I just hope I don't start having nightmares about cranks
exploding or oil filters blowing through the hood :-O
|> --
|> "Do you ever wish you had a joystick with a big red button on it so
|> you could just nuke the person when you send a reply?" -- Kim
|>
|> Scott Fisher/sfisher@wsl.pa.dec.com/DEC Western Software Labs/Palo Alto, CA
Bob Jones
bobj@meaddata.com
Mead Data Central - Dayton, Ohio
|