Is it normal for a faulty oil pressure switch to leak?

[starbiscuit]

My bus used to use a lot of oil. It would get from dipstick max to min in a hundred miles, which is a staggeringly bad 50 miles per pint I think.

It used to be obvious; you could see it running down the case from under the fan shroud and there was an oily film over the back of the bus. It turned out that the oil cooler seals were brittle and ineffective. That was fun.

Now I have the issue that the oil pressure light doesn't always come on before I crank, but I know it comes on when there is no oil.
And the electrical connection to the switch is constantly oily.
Consumption is better than it was but not great, and the amount in the drip tray on the drive isn't too bad, so it's not losing much while parked.
I don't think the engine is burning it because I asked a friend to follow and it's not smoky or oil-smelly.
But I think it is using more under load or at higher revs that I don't see at idle.
I will replace the switch anyway, because the warning light should be on before cranking, and it is cheap enough.

Here's the question: is it likely that the switch itself is leaking oil right through, or are there any other favourites in the area that could wet it?
I am running original single-vacuum distributor and mechanical fuel pump. Neither of them seems particularly oily, but it's all a bit oil-wet on that side of the engine and I can't see where it's coming from.

Thanks for reading

 

[sparkywig]

Oil pressure switches do leak, so I would change that anyway.
Original oil consumption from the factory is between 1.5 - 4 pints per 1000 miles, and the engine shouldn't leak any oil so you have a problem somewhere.
I'd drop the engine, give it all a good clean, check that all the head and case bolts/nuts are torqued correctly, and make sure the oil cooler seals are OK while it's out.

 

[bac2ba6]

As above they do leak but if your loosing that much oil that wouldn't be the only culprit as it would be everywhere inside you engine bay if it was . As said need to give it a really good clean down and check the common areas like oil cooler , push rods , even the threads on the sump cover you can get oil running down them and the copper washers between the nuts can get miss shapen if they've been over tightened , is there any oil dripping down from where the engine meets the gearbox ? As there could be a blown flywheel seal but again if there was loads of oil in there I would of thought the clutch would be slipping like a gooden . Untill the engine is cleaned up it's almost impossible to find a leak when there's oil everywhere [emoji106]

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[starbiscuit]

OK, so I've changed the oil pressure switch and copper crush washer and that at least is no longer leaking.
However, the tinware is wet (fresh oily) below the distributor and fuel pump on the left of the engine, and below the crank pulley (where there might be a leak or it might be collecting by gravity).
It is no longer obviously leaking from the oil cooler seals since those were changed a few months ago (there used to be a continuous bead of oil running down the case from under the fan shroud at idle)

Now what I noticed is that on 120 mile round trip, where I kept the revs down and speed at no more than 40 mph, the consumption is very much less than when I did the same trip at up to 50 mph. Like half.

I do not have an oil pressure gauge but I wonder if the leakage could be caused by too much pressure?
Is the pressure relief valve testable?
Is it likely?

Thanks for reading

 

[sparkywig]

It’s probably weeping from the oil cooler seals when the oil is hotter and thinner. Did you use any sealant when you changed them?