Morris Minor Owners Club

Hi all, the oil release valve is worn on one side of its skirt and seat only. Is this normal or the cause of the lowish oil pressure.

The oil pressure relief valve does wear on the skirt and seat.
The valve is easily replaced.
The valve should be ground into the seat (but is seldom done) which is a removable item inside the block. Do not attempt the removal of the valve seat as it is a specialist job and the seats are no longer available.
Low oil pressure is usually but not always caused by crankshaft bearing wear.

I would replace the valve and spring and leave it at that unless you are prepared to replace the big end bearings and the centre main bearing. To replace the front and rear main bearings requires the engine to be removed and stripped.

Thanks Phil. I would like to grind in a new valve, got grinding paste. But how do I grip the valve so I could turn it...

Thanks Phil. I would like to grind in a new valve, got grinding paste. But how do I grip the valve so I could turn it...

I would advise against grinding the valve to the seat as any grinding paste getting into the oilways will ruin the engine big time.
Only grind in the valve if the engine is completely stripped and you have facilities to fully deep clean the block. This is the reason the valve rarely gets ground in.
Just replace the valve and spring and do nothing else.

Phil

It's stripped on the bench . But how do I grip the valve..

It's stripped on the bench . But how do I grip the valve..

It's stripped on the bench . But how do I grip the valve..

And I should hit the 'Submit' button only once

I would take Phil's advice, he knows his stuff. I wish i had replaced my big end shells when my oil pressure dropped.

BMC used a special tool Pt No: 18G 69 - but you can grind/lap in the valve by using a piece of dowel wrapped in insulation tap and pressed into the hollow of the valve.
You do need to remove all the oil gallery plugs and brush them through to remove all traces of the grinding paste.
Absolute cleanliness is required post lapping the valve
This is the arrangement of oil galleries at the rear of the engine cutting through the oil pressure relief valve - it is complicated but simple.

Ah, that's the secret. Thanks Phil for your help. And I have all the shells already on the shelf.

Phil

Is there any advantage to doing a conversion to a ball bearing type valve, I think I read somewhere that it was a mod done on racing engines using a different length spring and a ball in place of the standard setup.

Phil

Replacing the plunger type valve with the ball bearing is a good mod and it ensures that the oil pressure release valve does not stick.

http://www.minispares.com/product/Class ... |Back%20to

http://www.minispares.com/product/Class ... o%20search

I note that the oil pressure relief valve seat (Pt No: 2A797) is shown in the Minispares link but is not available. The last valve seat I obtained came from the USA.

You do need to set the oil pressure post fitting the ball and an adjustable oil pressure regulator is a easy way of doing it.

http://www.minispares.com/product/Class ... |Back%20to

Those ball bearings (Mini driveshafts?) could be 'ground in' by use of a medium sized BFH, I guess. Just a suggestion. Best to check with Phil or some other Mini guru on one of the other forums.

Rob
There is absolutely no requirement to grind or lap the ball bearing to the seat.
The oil pressure relief valve and/or the ball bearing will spend most of its life off its seat anyway so as to facilitate the flow of surplus oil back to the sump.
I suspect that very few valves are ground or lapped in because of that and are just replaced with no ill effects or loss of oil pressure.
Phil

If it seats properly. But to go back to the beginning of my post, what if it seats only half of its circumfence, as in the above photo.

The valve will only be on its seat when there is no oil pressure or the engine is stationary so there is no absolute (note the word absolute) need to grind or lap the valve to the seat.
I would try a new valve and see how it seats - it is up to you as to whether you grind/lap the valve but you have been warned of the possible consequences of valve paste getting into the oil ways and having not being fully removed.

Phil

Thanks Phil. I'll follow your advice.