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Oil Pressure - again [message #176823] Sun, 15 July 2012 16:21 Go to previous message
Neil is currently offline  Neil   United States
Messages: 271
Registered: July 2007
Location: Los Angeles and Magalia, ...
Karma:
Senior Member
I am on my 3rd Jasper motor (but that's another story) and have developed a vexing oil pressure issue similar to that with previous motors.

First, let me say it runs great. The best ever. And it does not run hot at all. Even with a/c on while towing.

I have a Big Mac dash with an electric oil gauge and then being a not so trusting sort, mechanical gauges for everything too.

This motor has less than 15k miles on it. It is starting to do what prior motors did, which is show low oil presure.

On the last desert trip I was seeing hot idle down to 12 lbs, and hot running at 3000 rpm at about 30 - 35 lbs.

True confessions, a local mechanic down the street changed the oil just before that trip and I don't know what he used.

When I got home I changed oil and filter, used Shell Rotella 10-40, went for a drive to dump the black tank and it "seemed" better. I changed the oil again and after a few months finally took it for a drive today. It is doing odd things.

Cold start, good pressure, say 40 lbs at high idle. Once warmed up, it dropped to 15 lbs at idle with the a/c on which dropped it a bit further.

Went for a drive on an 85 degree day on the freeway up a slight grade, drove it 70-75 mph (water temp never got abot 185, oil was at 190) oil pressure at 3000 rpm indicated was 35 lbs.

When driving at 70 mph, if I lifted off the gas the oil presure would climb about 5 lbs and then drop when I pushed on the gas,

It is not over filled it is not foaming as far as I can tell.

Now here is the really weird part. After I got it up the driveway at home (long, twisty, uphill and a PIA to park) and the oil temp got up to 200, the pressure at idle was indicating 20 lbs.

My next step is to change the oil again and send a sample out for analysis. But none of this is making any sense to me. Both the mechanical and the electric gauge take their pressure readings off the same "t". Could there be some obstruction there? Any other good armchair guesses? I am afraid I will have a choice between doing 70% of the work of removing the motor to get to the oil pump vs remove the motor for a tear down when it works just perfect.

Right now I wish I just had an idiot light.

Neil
76 Eleganza now sold
Los Angeles

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