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yet another oil pressure story

Posted by chrisv

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yet another oil pressure story #1
chrisv chris vine Gawler , Adelaide, Australia 1979 MG MGB	Posted: June 27, 2012 02:25AM Registered: 1 year ago Posts: 383

This is the first winter in Adelaide (slight frosts) I have used my 79B. I changed oil to Penrite 25W 70 from the Penrite 20W60 the PO had been using.
When I start the car the gauge registers 50lbs. After the car is warm it runs at 60lbs at around 3000 rpm, Hot idle is 50 lbs
Engine is 65000 miles
Any thoughts?
Cheeers

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Re: yet another oil pressure story #2
Red Roadster Iain Trainor Perth, Western Australia, Australia 1969 MG MGB "The B" 1999 MG F-Type "The Lad" 1999 MG F-Type 2009 Nissan X-Trail	Posted: June 27, 2012 04:05AM Registered: 1 year ago Posts: 141

Chris

Sound like it is all within spec. It was certainly chilly (down under conditions)your way today.

Is there any significant difference using the different grade oil? I am using castrol 20W50 with the zinc additive. That was the recommendations of the engine remanufacturer however Penrite is good quality oil.

Cheers from the west at 20 degrees but cloudy sad smiley

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Re: yet another oil pressure story #3
rdgreen Robert Green Adelaide, Australia 1975 MG MGB MkIII	Posted: June 27, 2012 04:40AM Registered: 1 year ago Posts: 735

Pressure is ok. Could be a little higher when running, but nothing to worry about yet. I use Valvoline 20W50. Warm it runs 75lbs, at idle 50lbs

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Re: yet another oil pressure story #4
rundjk David Kinsey Virginia Beach, USA 1980 MG MGB "Runaway"	Posted: June 27, 2012 04:56AM Registered: 3 years ago Posts: 1,476

If the 60 and 70 mean the same there as here, that seems a bit high. What's your reasoning behind wanting that grade? Those oils would be for very high temps I believe. Much of the wear and tear on an engine is in the first couple of minutes of a cold start and having a thick oil does not help that factor.

David

David J. Kinsey
Virginia Beach
Tidewater MG Classics
1980 MGB "Runaway"

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Re: yet another oil pressure story #5
chrisv chris vine Gawler , Adelaide, Australia 1979 MG MGB	Posted: June 27, 2012 05:11AM Registered: 1 year ago Posts: 383

I changed the grade as I believe I have a problem with No3 cylinder with a broken oil control ring and I thought by going to a heavier weight oil it might reduce my oil consumption
My query is why pressure rises when hot. Anyway, I am going to revert back to Penrite 20W60 next week when I do a service. Will be interesting to see any change in pressure. If only there was no gauge life would be so simple

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Re: yet another oil pressure story #6
the omega man phil wilkins staffordshire, United Kingdom 1973 MG MGB GT	Posted: June 27, 2012 05:29AM Registered: 2 years ago Posts: 1,688

Chris,mine has always risen when hot as well.the gauge jumps to 60 lbs straight off and does not move untill the engine is hot. when the engine is hot it rises to 70 lbs.and the needle moves lower upon tickover.
I can only assume that the oil is so thick when cold that it struggles to move through the capillary tube to the gauge.I have noticed that in a cold winter it takes a lot longer for the gauge to start working properley.

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Re: yet another oil pressure story #7
chrisv chris vine Gawler , Adelaide, Australia 1979 MG MGB	Posted: June 27, 2012 06:32AM Registered: 1 year ago Posts: 383

Thanks for the replies smileys with beer

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Re: yet another oil pressure story #8
RAY 67 TOURER Ray Marloff Fort Bragg, CA, USA 1967 MG MGB "My Girl"	Posted: June 27, 2012 04:38PM Registered: 3 years ago Posts: 5,932

If you do have a broken oil control ring it can be causing you further damage by running the engine. You should ascertain what the source of your oil consumption is before any more damage is done to your cylinders. RAY

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Re: yet another oil pressure story #9
curtis7420 Curtis Wright Univerisity City, MO, USA 1975 MG MGB "The "B"" 2000 Chrysler Town & Country 2003 Toyota Highlander 4WD	Posted: June 27, 2012 06:24PM Registered: 2 years ago Posts: 1,899

i ran my engine with a broken ring and put a pretty deep gash in my cylinder wall. so much that when i put in a new ring i still had/have blowby. i now have to get a sleeve put in that cylinder to correct the issue...

think twice about driving around with a broken ring

good luck

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Re: yet another oil pressure story #10
chrisv chris vine Gawler , Adelaide, Australia 1979 MG MGB	Posted: June 27, 2012 07:50PM Registered: 1 year ago Posts: 383

The broken oil ring is only 'an assumption' at this stage. I plan to pull the head and see in spring.
I really have no idea as car runs well no noises but drinks oil and shows oil in No3 plug. So much so if I remove the plug and stick a paintbrush in the hole it comes out dripping. No's 1 2 and 4 all dry and plugs a nice tan.Fingers crossed it may be a valve guide although head was replaced 4000 miles ago by PO with paperwork to show No3 exhust valve with issues and water in N0.3 cylinder. compression readings are all 160 with No3 145

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Re: yet another oil pressure story #11
ClayJ Clay Johnston Mt. Olive, MS, USA 1972 MG MGB	Posted: June 27, 2012 09:03PM Registered: 7 years ago Posts: 7,351

Chris,
That seems like a heavy oil for cool temps.

If a valve-stem seal doesn't help (probably not), its time to take action.

Your OP numbers are fine. You might consider pulling the head and the #3 piston for inspection.

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