M42 running VERY loud (video), low oil pressure light is on

[Vivek]

Shit dude, really sorry to hear this. I cannot imagine what it is at this point if the oil pressure light is on (and you measured a big zero), other than a completely destroyed or missing set of oil pump gears. You said that this engine was running strong when you bought it, and you didn't swap or do anything with the timing case right? The only way I can think that the oil pump is not operating is if the PO of the engine blew out the gears and sold you a dud.

I know how you are feeling as I was there about a year ago. I had waited a year for a custom M42 to be built and had a valve spring crap out 70 miles in. Pulled the engine and shipped it to the builder to get fixed. Put it back, things were going well, and then another one broke at 1000 miles. I was seriously going to get the head fixed and sell the bastard. Buy a used Civic and get from A to B with no more bullshit. Thankfully, I had some guys on M42Club keep up the encouragement (Warsteiner, wazzu, DesktopDave) and it turned out fine. It took hours of bloody knuckles, sweating and anger to get through it, but it all worked out. You'll be fine too, and in a few months it won't be a big deal for you.

I think I'll pull my oil pressure sender again, start it up, and see if it squirts oil. Maybe I'll pop the oil cap off too and see if I can see anything. Is there anything I can do to make it less bad that my car is pretty much running with no oil circulation? Anything I can lube manually to try to help it out? I started it yesterday shortly after filling it with oil with the hope that at least part of the engine would still have some residual oil on it.

I've already contacted two shops requesting they fix it. One thinks oil pump or timing chain guides. The other hasn't responded yet, but the second shop is less than 100 miles from my house and I have AAA towing up to 100 miles. Also I got the second recommendation from a friend and they're classic bmw specialists.

Anyways, I got the engine from a close friend, saw it running days before it was pulled. I have full confidence it was 100% fine before it was pulled, other than the aforementioned timing chain rattle.

Maybe it's the oil pump, but idk how that would happen. Maybe I installed the timing chain tensioner wrong, and the oil sensor broke or is hooked up wrong so it's reading 0 while it is actually getting pressure. All I know is that I haven't driven my car in 7 months and I'm pissed as fuck. Never been so frustrated and fed up ever.

[kwill22]

We're absolutely positive that the timing is on par right? Just trying to eliminate things

Sorry to hear man, I think a bunch of us have been to the point where we wanted to take a sledge to the car. I know I have.

[bmwm42]

I've said it all along I'm blaming the oil pump

[bmwman91]

Vivek, you put an oil pressure tester on there and saw zero PSI right? Or have you been going based on the stock pressure sender all along? It is entirely possible that the sender is just crapped out and something is up with the tensioner piston. You put a new one in right? Take it back out and see if it is full of oil. If your oil has been circulating then it should be an oily mess. Contrary to one of the suggestions above, the only really safe way to install it is to decompress / expand it and then install it. Putting it in compressed and waiting for the chain to smack the rail around enough to break it loose is asking for broken rollers on the chain...which WILL end up in the oil pump.

[bmwman91]

I've said it all along I'm blaming the oil pump

Yeah, if pressure actually is zero, then it's gotta be the pump. I'd think anyway. If he got the engine from a friend and it was in running condition, then I can't imagine how the pump would have failed.

[kwill22]

Also if the pump is dry It won't prime since your engine has been sitting.
I've had similar experience with the hydro pumps on lifts

You could also try to prime the pump manually by turning the crank. Rig over the lower pan and hold a container of oil to the pickup tube and see if it'll suck.

[wazzu70]

Yeah, if pressure actually is zero, then it's gotta be the pump. I'd think anyway. If he got the engine from a friend and it was in running condition, then I can't imagine how the pump would have failed.

Depending on the routing of the oil system to the sensor/oil filter block. Is that the first stop along the path? I cant remember.

If the main galley is before that and its missing a squirter the oil system will not build pressure because there is no restriction. The oil just dumps out the open hole. 0 pressure does not mean 0 flow, it means there is not the right amount of flow restriction.

Maybe remove the oil filter housing block and see if any oil exits the pump when you rotate the crank.

The oil pump is a gerotor driven by the crank snout. Not a lot to fail there.

[Vivek]

Well I pulled the pressure sender and cranked the engine (before replacing the valve) and not a drop of oil came out. I couldn't find the right fitting to hook up an analog gauge. I'd guess a dud/incorrectly installed tensioner if it is indeed getting pressure. I installed it uncompressed. The timing should be correct unless it jumped a tooth, in which case I think it'd bend the valves/not run at all.

About priming the pump, the engines been run for about a minute, minute and a half, would that be adequate to prime it?

Would a broken oil squirter fall down into the pan? There wasn't anything in it when I pulled it.

[bmwman91]

Depending on the routing of the oil system to the sensor/oil filter block. Is that the first stop along the path? I cant remember.

If the main galley is before that and its missing a squirter the oil system will not build pressure because there is no restriction. The oil just dumps out the open hole. 0 pressure does not mean 0 flow, it means there is not the right amount of flow restriction.

Maybe remove the oil filter housing block and see if any oil exits the pump when you rotate the crank.

The oil pump is a gerotor driven by the crank snout. Not a lot to fail there.

The sender is before the outlet to the galley. Looks like it has toe pump based on what Vivek is saying about cranking it with the sender removed and nothing coming out.

Vivek, if you remove the oil filter cover is there any oil in there?

I've never had an issue with the pump not priming. When I had my new engine start for the first time, it was noisy for 3-5 seconds and then built the necessary pressure. After oil changes, it is noisy for 1-3 seconds usually. Being a positive displacement gear pump, I cannot imagine it having any real difficulty sucking oil up the sump if it is properly submerged. But then again, my range of experience is fairly narrow so maybe it really is a big issue.

[kwill22]

When it primes it only takes a few seconds. If it's taken a minutes then it probably isn't going to happen. But the pump needs to be lubed in order to prime. It needs restriction as said above to work. Sounds funny but that's how hydro pumps work.

A slightly different design but same concept


The only way those gears move any fluid is if you pack them with some kind of grease usually to create resistance and vacuum

[roguetoaster]

Could he just stick a grease gun in the oil pickup (to pack the pump) and perhaps prime/create resistance at the pump? Along with some hand rotation of the engine I would think that would solve it if the pump simply needs to be primed/filled.

On the down side, if that does not work it will create quite a clog that would have to be cleared.

[bmwm42]

Depending on the routing of the oil system to the sensor/oil filter block. Is that the first stop along the path? I cant remember.

If the main galley is before that and its missing a squirter the oil system will not build pressure because there is no restriction. The oil just dumps out the open hole. 0 pressure does not mean 0 flow, it means there is not the right amount of flow restriction.

Maybe remove the oil filter housing block and see if any oil exits the pump when you rotate the crank.

The oil pump is a gerotor driven by the crank snout. Not a lot to fail there.

Ive had many people that say ....I mean the oil pump is nothing but a sprocket rotating inside the timing case but they do wear. ...and the pump does need to primed just ask gerta he had a similar situation....I don't claim to be a expert but I do have a fair amount of knowledge regarding the m42.

[wazzu70]

I know the pumps can fail, its just a long shot due to the robustness. At this point though, the options of being much else are being reduced and the pump is one of the only things left.

The RB Nissan motors have a similar pump, and they have issues so its not unheard of.

I have never packed any with grease though. I usually install dry and have no issues getting it to pick up oil and work fine.

[kwill22]

There's a specific type of grease that's used for for pumps. It usually dissolves into the oil. It isn't a problem with hydro pumps usually but on a car I'd change the oil after just for peace of mind. But as far as just greasing the pump with a gun. I don't see any issues with that just make sure the proper lube/grease is used. You can do more research on grease or fluids to use and how "safe" it is. If it doesn't prime with grease usually the pump is most likely bad.

[bmwman91]

I don't think that there is really any easy way to shoot grease up into the pump. You would probably have better luck pouring some 15W-50 into the oil filter housing and letting it flow backward to the pump gears to get them lubed up. I don't recall if there is a check valve in there, so you might need to remove the filter housing to be able to pour oil into the pump outlet. I assume that the idea is that a dry pump will just be circulating air between the small tolerance gaps in the rotors, and adding some grease/oil will fill in the small gaps and allow it to build suction?