Help! No oil pressure! 4.6 V8

[SuperV8]

Fix the relief valve and go from there

I would not be wasting time/effort removing the sump and bearing caps.

And as already said, cut open the oil filter and inspect it. If there is no large signs of trauma, lots of metal etc.....then chances are things are fine.

Work smart, not hard.

The OP shared a photo of the oil filter contents - which looked quite glittery to me! which is why I would personally investigate further. Each to their own and they have to decide what is ok/fine for their car. I don't know what it is - a battered old Landy - or a cherished something?

How about work smart & hard!

[rich112]

Fix the relief valve and go from there

I would not be wasting time/effort removing the sump and bearing caps.

And as already said, cut open the oil filter and inspect it. If there is no large signs of trauma, lots of metal etc.....then chances are things are fine.

Work smart, not hard.

The OP shared a photo of the oil filter contents - which looked quite glittery to me! which is why I would personally investigate further. Each to their own and they have to decide what is ok/fine for their car. I don't know what it is - a battered old Landy - or a cherished something?

How about work smart & hard!

Well I was in 2 minds to lift the motor out and strip it or just see if the pump will provide some pressure now the valve is moving.

The car is cherished and I was planning on getting the motor out and tarting it all up a bit, just wasn't planning to do it quite so soon after buying the car!

I could start dropping caps off but from what I've read about cross bolted caps, I didn't want to get too bogged down in getting them off just yet.

I'm going to spin the pump up and see what happens. Either with the drill or starter. If I get some pressure, I'll see what the motor sounds like running. If it's knock free, I'll call it a win and go celebrate and leave the rebuild for Winter.

I can't see any major damage, the rockers look ok, cam from what I can see looks ok. Yes there's some glitter in the oil and ferrous material in the sump sludge but that may have been there from years ago.

Fingers crossed!

[SuperV8]

Sounds like a plan. Fingers crossed.

[rich112]

Sounds like a plan. Fingers crossed.

And toes...

If my gaskets arrive tomorrow, I hope to get somewhere with it by the end of the day!

[rich112]

curiosity got the better of me, so I took out a main cap.

Not easy as they are tight fit between the sides of the block.

No gold showing.

One odd indentation from something once!

[DaveEFI]

I'll say again. Even with knackered bearings you'd still have some pressure.

[stevieturbo]

Fix the relief valve and go from there

I would not be wasting time/effort removing the sump and bearing caps.

And as already said, cut open the oil filter and inspect it. If there is no large signs of trauma, lots of metal etc.....then chances are things are fine.

Work smart, not hard.

The OP shared a photo of the oil filter contents - which looked quite glittery to me! which is why I would personally investigate further. Each to their own and they have to decide what is ok/fine for their car. I don't know what it is - a battered old Landy - or a cherished something?

How about work smart & hard!

Didnt realise that's what the photo was....it's always best to leave it in the pleats where it has gathered than pour it all onto a rag. Let's you see all the pieces better so you can also test with a magnet etc. Plus get a good picture of overall quantity

Main bearing looks fine, but it will always be the rod bearings that suffer first.

Again...get the pump back together and spin it up with the drill.

[SuperV8]

I'll say again. Even with knackered bearings you'd still have some pressure.

It wasn't suggested that the bearings were the 'cause' of the low oil pressure! - Just that low oil pressure can damage bearings - and the OP though a bearing may have picked up?

[GDCobra]

Seems like a lot of pain for no gain but each to their own.

[rich112]

Good news so far....

Primed up the pump and saw 30psi on the gauge. Primed immediately with the drill and vaseline in the pump.

Going to put the dizzy back on and turn her over on the starter next...

[rich112]

Seeing 24 PSI on the starter motor after 15 seconds turning over...

[DaveEFI]

Seeing 24 PSI on the starter motor after 15 seconds turning over...

Good news. Are you now sure of the cause?

[rich112]

I think the issue was the relief valve. It was tight in the bore. Not rock solid, but it didn't slide out on its own.

It's a nice sliding fit now.

So I have just fired up the motor and it's running, without any horrible knocking or rattles, but it needs proper ignition timing setting.

Riddle me this: I thought the oil pressure should limit at 28 or 30 PSI and at idle I should see 10 or maybe a bit less.

When I first got the car, I am sure this is what I was seeing.

Now I am getting 34 PSI at about 1500 RPM and even at idle it's 25 PSI. (EDIT: Maybe this is just because it hasn't reached normal operating temp yet...)

Looking at my oil pump there is a warning pressure switch and a gauge BUT they come off different places. The warning light goes nowhere as there isn't a light on the dash that I can see.

Is it possible that the gauge is reading pressure before the relief valve?

My pump is an uprated one I believe. Not with the add on sandwich block, but I think its a later pump as the gears are quite deep.

Maybe this is how this sort of pump should run and before the relief valve was dropping the pressure all the time? It just got more stuck in the wrong place and completely dumped all the pressure...

I'm running some Morris Golden Film SAE 30 mineral oil through it at the moment to flush the old stuff out and I'll replace that with 10W40.

(Edit: Will set timing and run longer so oil gets warm and monitor pressure tomorrow!)

There's where the oil pump gauge and warning switch are plumbed in:

[GDCobra]

Going from memory I don't think it's possible for anything to measure pressure before the relief valve as the valve acts direclty on the pump area, it sits in the area where the pump gears are generating pressure.

Don't really know what you mean by an uprated pump, as far as I know where have only been two pumps (prior to the crank driven one used on non-distributor vehicles), the early one, up to P6 era and the later one which came in around the time of the SD1. The later one has longer gears giving greater capacity and hence flow but not (necessarily) any more pressure. I guess it's possible to upgrade the shorter style to the later version with a spacer plate and the later gears, but that's not something I've ever looked into as I dont' need to.
There are after-market upgrades available such as stronger spings (pretty sure I have one of these in mine).

It sounds like your pump may have always (during your ownership) been allowing some flow through the pressure relief valve hence dropping the pressure and just got worse or it may be that the different oil you have in now is allowing the downstream system to generate more pressure. Either way that can only be a positive thing IMHO.

Good news on the 'fix', lucky you caught it in time before the low pressure caused further issues. Always best to have a light as well as a gauge. I have a sad story about that!

[rich112]

Going from memory I don't think it's possible for anything to measure pressure before the relief valve as the valve acts direclty on the pump area, it sits in the area where the pump gears are generating pressure.

Don't really know what you mean by an uprated pump, as far as I know where have only been two pumps (prior to the crank driven one used on non-distributor vehicles), the early one, up to P6 era and the later one which came in around the time of the SD1. The later one has longer gears giving greater capacity and hence flow but not (necessarily) any more pressure. I guess it's possible to upgrade the shorter style to the later version with a spacer plate and the later gears, but that's not something I've ever looked into as I dont' need to.
There are after-market upgrades available such as stronger spings (pretty sure I have one of these in mine).

It sounds like your pump may have always (during your ownership) been allowing some flow through the pressure relief valve hence dropping the pressure and just got worse or it may be that the different oil you have in now is allowing the downstream system to generate more pressure. Either way that can only be a positive thing IMHO.

Good news on the 'fix', lucky you caught it in time before the low pressure caused further issues. Always best to have a light as well as a gauge. I have a sad story about that!

Yes I think I have the SD1 era pump, fitted to a 4.6 so it can run a dizzy and carb.

It's odd that someone put on the pressure warning switch but no light. The Morris Minor speedo doesn't have an oil pressure light, but other Morris cars do. Anyway it will be a worthwhile mod to add one somewhere!