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MG TD TF 1500 - Oil pressure - again

Oil pressure was always 60 at speed and 20 at idle. Last week I changed oil (again with 15W40) and filter (vertical type). But since then the readings show 40 at speed and 15 at idle.

I know these are still good results but yet I wonder what happened.

Anyone has a clue? Should I worry?

Jasper

JL Nederhoed

Same make of filter?
Gene Gillam

Gene,

No, the old one was n/a anymore. Could that be the cause?

Jasper
JL Nederhoed

Jasper...

It would be the first thing I'd check since it's the only difference between what you started with and what you ended with.

Gene
Gene Gillam

Maybe the old filter was partially clogged?
Jim Merz

Jim,

Wouldn't that lower oil pressure? The pressure gauge is after the filter.

Gene
Gene Gillam

Gene,

Old one = Unipart GFE 180
replaced by MANN Filter W-712/43

Jasper
JL Nederhoed

I guess you are correct Gene. Thanks for getting my head straight.
Jim Merz

Jasper I am no expert but when I read Mann filter I wondered. I use these filters in my Mercedes sedans and roadsters. They are fleece rather the paper filters and actually do a superb job filtering out micron size particles.

Perhaps this intense filtering has reduced the oil pressure because of the filtering and restriction of oil flow.

Joe
JWP Policastro

Joe,

Maybe you nailed it! Tomorrow I'll check what filter & make are the right substitutes for the Unipart filter.

Jasper
JL Nederhoed

The oil pressure of my TD is very high and the last renewed oil filter is MANN 715/19. That didn't change the pressure.
Bela

Bella you and Jasper are using different models. Maybe that could be it too.

Joe
JWP Policastro

Conform a cross-reference MANN 712/43 is the preferred replacement for Unipart GFE180.
2nd Choice would be MANN 714/3.

As far as I can see the only difference between these two is the color ;-)

Maybe I should try another make...

Jasper

JL Nederhoed

Tonight during a 30 mile ride oil pressure started with 40 but with a warm engine went down to 20 at speed and zero at idle.

And suddenly that seemed familiar to me...this is the same behavior she had from the moment I got the car. However, after a couple of years and some 4000 kms of happy driving the gauge suddenly returned to normal readings and remained that way. Until now I do not know the reason for this behavior. I thought maybe something got clogged and that was that.

Unfortunately the situation returned last week when oil was changed and a new filter was mounted. I have no clue but hope that someday she surprises me again...

Jasper

JL Nederhoed

Jasper,

I would not drive with your indicated oil pressure. Try blowing carb cleaner through the gauge line and if that doesn't help, swap out your pressure gauge with another one.

Gene
Gene Gillam

The delta between warm and cold and between run and idle looks right - approx 20 PSI in each case.
However, the absolute values are obviously wrong. My normal values are 60-70 at rpms and cold, 40-50 warm and 20-30 at idle warm.
If you did not touch the pipe to the oil gauge, then it must have to do with the filter/oil pump mechanism.

See my thread about the oil gauge getting stuck when the pipe to the meter was under strain and hindered the free movement of the gauge internal mechanism. Only relevant if you changed something in the engine room or under the dash that may put strain on the pipe that was not previously there.

Rgds, Mike
Mike Fritsch

Gene, Mike

Thanks for your ideas. I'm quite sure the engine is getting enough oil, so something should be wrong with the pipe or the gauge.

Last week we also mounted a new amp-meter, together with the oil change and new filter.

So Mike could be right: we were under the dash...I'll check things tomorrow.

Thanks again,

Jasper
JL Nederhoed

You may consider experimenting with your oil. Fresh 15W-40 is pretty thick, a diesel oil. I use it in our TDs also.

If you tapped a pressure gauge right on the pump, it would tell what is actually going on down there. Some may be dumping out the relief and cutting down what the engine receives.

Adding to that, the thicker oil would generate more backpressure at the filter contributing to that escaping the relief, which is what has been previously mentioned. BUT- bypassing the filter (not the relief valve, the filter bypass circuit) still feeds into the oil galley, so it would still contribute pressure & volume.

You may drop it down to 10W-40 and observe a boost in pressure.

Hondas call for 5W-20 and some of the engines have a very bad habit of spinning rod bearings. I question whether the use of 10W-30 or thicker oils actually cuts the flow down leading to bearing failure!
JRN JIM

You can buy a cheap pressure gauge with the plastic tubing and a brass fitting that is close enough thread to temporarily check the pressure to rule out gauge problems. Use a sparing amount of Teflon tape on the threads, remove the flex line and install there and just gently tighten. Interesting viscosity comments- I recently read the 5-20 and 0-40 oils were specified due to the variable valve timing mechanisms. In our hot southern climate we all use 20-50w. George
George Butz

This thread was discussed between 04/06/2016 and 11/06/2016

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