Help! No oil pressure! 4.6 V8

[stevieturbo]

cut the oil filter open and you'll see if it's full of debris

[rich112]

cut the oil filter open and you'll see if it's full of debris

Yep. I have the filter handy to check it. No sign of any in the oil but bigger bits will be stuck in the filter.

[Ian Anderson]

What does the borrom of the dizzy drive look like? Has or sheared off so thus not driving the pump? Or dizzy slipped up in clamp and the drive come out of contact?

Ian

[rich112]

What does the borrom of the dizzy drive look like? Has or sheared off so thus not driving the pump? Or dizzy slipped up in clamp and the drive come out of contact?

Ian

Will check Ian.

Today I will take out all the plugs, check to see if any are showing signs of head gasket failure and I can also crank the motor by hand and check the oil pump gear is moving.

I'll also take the relief valve apart and make sure it moves ok.

Lastly, try and get the sump off in situ and see what it looks like in there!

Really hoping it's going to be an easy (cheap) fix, but I suspect not...

[SuperV8]

My previous dizzy driven oil pump engine lost oil prime - from an oil/filter change. Took dizzy out and spun the pump on a drill and still wouldn't prime so took the bottom plate of the pump; packed with Vaseline and my oil pressure came back. These pumps aren't self priming.

[rich112]

My previous dizzy driven oil pump engine lost oil prime - from an oil/filter change. Took dizzy out and spun the pump on a drill and still wouldn't prime so took the bottom plate of the pump; packed with Vaseline and my oil pressure came back. These pumps aren't self priming.

Blimey, that sure is a cr@p oiling system!

My pressure has gone pretty suddenly. No reason that I have found, yet.

I just thought the oil pump and valve was the best thing to look at first. The scoring was quite bad I thought, but that's not really a reason for it lose pressure suddenly where as a spun bearing is...

Actually, a thought has just occured to me. If the oil pressure gauge capilary tube cracked, you'd expect it to pee oil everywhere, BUT is it possible the pump would just suck air in and basically un-prime itself???

[DaveEFI]

Don't think so - it would need to pump out all the oil first. They normally only need priming if left fully drained down for some time.

I'd remove the dizzy and spin the pump with a drill and say the oil pressure switch removed. Oil should pump out the hole. Last engine I had that ran big ends still had some oil pressure.

[rich112]

Here's the piston from the pressure relief valve.

Wasn't jammed in, but didn't just fall out either.

Oil is defo smelling burnt...

[stevieturbo]

The fact you say it was tight in the bore is a red flag.

It would only need to be unseated a very small amount to allow oil to bypass.

So either hone the bore out, clean thoroughly etc and re-fit. And/or also fine emery on the piston itself to ensure a totally smooth and unhindered travel into the bore and down to its seat.

Bit of wet/dry should be fine for either. But it must be totally smooth and free.

Then put it back together, pump packed with vaseline etc, and remove the dizzy and prime the pump with a drill until you get oil pressure. I'd be loathe to turn the engine on the starter to try and get oil pressure as those old RV8 pumps can be a nightmare for priming.

[DaveEFI]

I've done quite a few packed with Vaseline, and not had a problem. Never tried priming a dry one with a drill, though. I can't see that working, as it needs a reasonable seal to start sucking.

[rich112]

This isn't look too good...

This is from the oil filter, which I have just cut open.

No chunks or flakes but defo a very fine gold glitter.

Oh and here's the other sid eof the oil pump. The sides of the pump housing look rough to me. They don't feel terrible, but not silky smooth.

The pump turns ok with the crank (by hand).

[stevieturbo]

I've done quite a few packed with Vaseline, and not had a problem. Never tried priming a dry one with a drill, though. I can't see that working, as it needs a reasonable seal to start sucking.

Priming with a drill has been standard paractise for decades, has nothing to do with seals.

And roll the paper out from the filter to see what has been caught in the filter pleats.

[stevieturbo]

Also

https://www.gomog.com/allmorgan/plus8oil.htm

And a simple cheap priming tool to spin the pump, basically same as I did 25 years ago. Bit of threaded rod and a M10 extension nut with a slot cut out to drive the pump in lieu of the dizzy.
Or you can buy tools cheaply if needed.
Just means you can run up the oil system without having to turn the engine over so you know you can be safe prior to starting.

[rich112]

Had a look in the sump.

No shavings or chunks, but the sludge is ferrous. I can pick it up with a magnet.

Also found a metal collar, possibly off a rocker cover gasket?

Not sure where to go next.

I don't know if the relief valve had stuck. Not sure how far it moves out to open and drop the pressure.

The pump walls look rough.

Gold glitter in the oil and ferrous sludge in the sump.

Should I try taking off a big end caps or main caps? Should I take a look at the cam and followers?

I think the motor has to come out anyway now...

[GDCobra]

I've done quite a few packed with Vaseline, and not had a problem. Never tried priming a dry one with a drill, though. I can't see that working, as it needs a reasonable seal to start sucking.

I’ve tried priming with a drill and never had any joy, that’s with a proper tool which engages fully on the oil pump shaft, ran for ages with drill on fast speed. Nothing!
Packed with Vaseline up to pressure in seconds. If you already have the pump apart packing with Vaseline is a no brainier (unless you’re a bi5 embarrassed about purchasing).