I jumped in the Mini this morning and was shocked to see that oil pressure had dropped to 35-40 PSI runningand 25 at idle. Now the oil pressure was spot-on in the Cooper yesterday at 100 PSI running and 75 PSI at hot idle.

What could cause the oil presure to drop so dramatically? I'm thinking the pressure relief spring or valve has jammed, and I'm guessing(read:hoping) there's no spun bearings or anything as the mini only got midly thrashed yesterday.

Any other ideas?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Check the pressure gauge. I had a similar problem but the capilliary line had become loose on the back of the gauge. (oil in behind dash, not fun)

Check oil level?

If it is a correct reading then take out the oil pressure relief valve, check / clean etc.

How long since you did an oil change? How old is the filter?

Did you block off the oil bypass in the oil filter head? If so and the filter is being blocked.....

Hope this helps

Cheers
matt

Yeah oil level would be my first reaction...

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Lillee - 1969 Morris Mini K

Nah oil level is spot on, I reckon I would hang my head in shame if I let the oil level get too low

The oil change was less than a thousand ago including filter, I don't think my filter housing has the bypass (it's the orignal one fitted to the MK2 S and as such I don't believe it had a switch or the bypass did it? I might be wrong). If it did, would this cause the pressure to drop? I thought it only opened because the oil pressure on that side of the filter was HIGHER than normal, and therefore was only trying to ma\intain the normal pressure.

I'm hoping it might be the relief spring, but I'm also hoping it isn't anything deeper, like a gallery plug, spun bearing or something.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

The bypass in the filter head (perhaps only present in the later spin on type) is to let oil circulate if the filter gets blocked. if the filter is getting blocked (which it wouldn't be in your case) then the pressure may drop. Particularly if you don't have the valve to let oil circulate.

It is looking mst likely to be the oil pressure relief valve / spring. Pull em out and have a look!

Cheers
Matt

Okey Dokey, will do.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Might need to clean out the "pressure limit valve" in the side of the block,,,sh!t/crud can jam it open(ish)

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Hi Matt, is this something different to the oil pressure relief valve?

Cheers
matt

Just pulled the pressure spring and ball bearing then (and also fitted my D4R85 dizzy too....ver nice), cleaned it and then re-installed.

Still the oil pressure is low at 35-50 PSI . I'm thinking now I might have a bung oil pressure gauge (I was piddling around up there putting in some globes into the speedo), maybe I buggered the gauge up somehow. I've never had anything except full pressure ever on that engine..

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

A common problem on Minis with the 9/16" steel ball put in there.

What happens now is the pressure forces the ball back off its seat, there is nothing to hold the spring straight and sometimes it bends around, flicking the ball sideways so it doesn't seal on the seat.

Cut a piece of 5/16" diameter steel rod 40mm long, and put it inside the spring to hold it straight.
This allows 8mm for ball movement which is heaps.

I've done this to lots, works every time.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc, will do.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Nope, wasn't that. I made the little 40 mm piece of 5/16 from the smooth shank of a loooong bolt and put thaqt in, but no dice. It must be the gauge


All pray:
Our father, who art in heaven, hallowed be thy name,

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Prays....

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Ian - My Ve SSV Ute - Looking for a Mini

Don't worry, it happens a lot. People put the so-called `Cooper S' ball in and bolt `er up. Then this happens... you crap bricks when the pressure drops, but never seen it do damage.

Mick,
Get another gauge....
Did you take the ball out for a look- maybe it was stuck. It's a pretty loose fit in there though.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc,
I pulled the ball out, it didn't want to play the game. I had to get a large rare earth magnet I scored some years back and put it onto a large screwdriver to give it the magnetism to pull the ball out. It stuck to the car, the block, the starter, the solenoid and then I finally got it to the hole to pull out the ball.

Yeah not many oil pressure gauges on EBAY at this very exact second. No-one bid on them please, I'm looking for a bargain

I trashed the garage looking for spare smiths oil gauges, but all I got is an Smiths Ammeter (Ampmeter if you will), a strange but quite nice graduated Smiths temperature gauge and a standard Smiths temp gauge. I might have to canvas for a spare one somebody might have lying around.

Still with 30 PSI of pressure, that is actually ample enough oil pressure isn't it even if it wasn't the gauge, I'm gonna try and find one of those cheapies to test it out.

All pray:
Allaahu Akbar (4x)
Ashhadu Allah ilaaha illa-Lah (2x)
Ash Hadu anna Muhamadar rasuulullah (2x)
Hayya' alas Salaah (2x)
Hayya' ala Falaah (2x)
[Fajr only] A-Salaatu Khayrun Mina-Naum (2x)
Qad qaamitis Salaah (2x) [Iqama only - not recited in Athan]
Allaahu Akbar (2x)
Laa ilaaha illa-Lah

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.