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

[wazzu70]

No easier way.

[bmwman91]

No easier way.

Yup. Sucks. I think that you should be able to unbolt the upper pan and slide it enough out of the way to deal with the valve without totally removing it, but it's a pain either way.

You can pull the oil filter housing to see if the check valve is at least in there at all, or if it is in a weird position.

[Vivek]

Yup. Sucks. I think that you should be able to unbolt the upper pan and slide it enough out of the way to deal with the valve without totally removing it, but it's a pain either way.

You can pull the oil filter housing to see if the check valve is at least in there at all, or if it is in a weird position.

Where would it be? Does anyone know of a DIY link to this procedure?

So here's my plan:
Fill more oil (currently halfway between the lines on the dipstick)
Crank with fuel pump fuse pulled
Start it up and rev it a bit if anyone thinks that may help and not damage anything
Most importantly, I need to measure the oil pressure during all this and I really don't know how

If all that fails, I'll go ahead and replace the check valve. Would it read 0psi under cranking with a bad check valve?

[Todd Black 88]

Don't start it if you cannot get adequate oil pressure by turning it over for a few seconds with the fuel pump fuse pulled.

Have you confirmed if your getting oil to the head? Is your oil pressure sender connected?

[Vivek]

Okay. Oil pressure is 0 under cranking. I pulled the oil pressure sensor, left the hole open, and cranked it. Not a drop came out. Does anyone have a DIY for the oil pressure relief valve?

If anyone is local I'd seriously pay you to do this for me at this point.

[bmwman91]

Hang in there man. I know exactly how you are feeling at the moment. I was there about a year ago after my second broken valve spring on a brand new M42. You'll get it running and this will all be behind you soon enough.

If you unbolt the upper pan and slide it out of the way, the relief valve is on the driver's side in the timing case. It is reasonably easy to swap out. Check the diagram for parts & location.

http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_0504&hg=11&fg=30

Pull the valve cover and check the condition of the cam lobes while you are at it.

I can't think of anything else that it might be other than a missing or seized relief valve. The whole "priming" the pump thing never made sense to me since everyone routinely changes their oil and never has to deal with it after draining the system. Maybe someone here can shed a little more light on that before you start turning wrenches, but my bet is on the relief valve. Or, is there any possible way that the oil pump gears were not installed in the timing case? What is the story with the engine before you bought & installed it? Now that I think of it, seeing ZERO oil come out of the pressure sender hole might indicate that there are no pump gears in there. I can't think of any way that the filter housing would be so plugged up that nothing got past the filter or internal bypass check valve. Try removing the filter housing cap and filter and turning the engine over to see if there is any action. Even with the relief valve busted you should get a little something in there.

[Vivek]

So basically all I do is drop the pan and the valve is right there? No need to remove the timing case cover or anything? The engine was running fine in my friends car. I'd known the car and engine the entire time he had it, and I also knew the PO. It had just started to make a timing chain rattle sometimes upon startup, so he pulled it for his s50 swap. Engine was excellent, cam gears and lobes were prefect at least before this issue happened. I can't think of any way the oil pump could be an issue since I never touched it, but who knows.

So what I'll need is:
Upper and lower oil pan gaskets
Updated versions of parts 5-8 on that realoem diagram

That's it?

[bmwman91]

Yeah that sounds about right. I have only ever replaced the bypass parts with the timing case off of the car, but I think that you should be able to do it with just the oil pan out of the way.

If it was running fine before and nothing got changed on the engine during the swap then I really don't know what it might be. I can't see any reason why the bypass would choose to poop out now. How long did the engine sit for?

[Vivek]

It was dry for maybe 2-3 months I think? Could have been a little longer. My only thought is maybe the rattle before it was pulled was caused by a failing bypass valve not getting adequate pressure on startup

So in this pic is it the little black circle in the bottom left held on by a circlip? I'm totally blanking but where the hell is the oil pickup? Edit so I think the pickup is attached to the upper oil pan. Is there anything special I have to do when installing the pan to make sure that works? Could that be my issue?

[bmwman91]

Yeah the bypass is the round thingy with the circlip in the lower left of the photo.

The oil pickup is attached to the upper pan, and the oil passes through the hole to the right of the bypass in the photo. You absolutely need to make sure that none of the threads in the timing case are stripped. One failure mode on these engines is that the bolts holding the upper pan to the timing case fall out, and then the gasket that seals the oil pickup route between the timing case and upper pan implodes. So I guess that could have happened too, although it seems like you would get a little oil flow.

[Vivek]

Well, I'll pull my pan in the next week and update with pics. I'll make an order for the valve parts right now. Thanks so much for your help so far.

[bmwman91]

Sure. Hopefully the valve is the issue so you don't waste $40! I usually try to pull things apart before buying parts, but waiting an extra few days isn't always an option.

[Vivek]

If I pull it all apart I might as well replace it. The valve itself is only like $15, the two gaskets that I'll definitely need to replace if I pull the pans cost that much each.

[Vivek]

Another thing. It looks like my brand new oil pan gaskets have been leaking. I'm working on pulling my pan so they'll be replaced, what should I do differently to ensure they don't leak? I used VR paper gaskets with hondabond on both sides. I believe I guesstimated the torque specs because my wrench doesn't go low enough, but I'll have to double check that. If they're safe to torque to 20ftlb I'll do that upon reinstallation.
Lower pan:

Upper:

Timing case could be leaking slightly, I didn't touch those gaskets. but this is leaking a LOT.

Amount of oil leaked after about 1 minute total of running

[bmwman91]

What kind of oil are you running? Synthetics will just leak a lot and it is tough to avoid if you use stock paper gaskets. RTV / Hondabond will help, but not stop it. The only way to be sure is to skip the gaskets and just use some Permatex Ultra Grey gasket maker, which is also a 24 hour process since you can only finger-tighten things at first and then torque it down after it cures. Doing that also makes it damn hard to get things apart again in the future. I would not skip the gaskets though since that changes some tolerances here & there.

Did you run the Hondabond stuff all the way around every bolt hole? Only running it around the outside will lead to some leaks.

Another common leak spot is where the two rubber profile gaskets butt up to one another on the passenger side. Oil pools there and will run out of the small gap a soon as you turn off the engine. You should clean that area with some alcohol and smear some Permatex Ultra Grey RTV over it and work it into the gap. Let it cure for 24 hours or the engine vacuum will just suck it into the timing case area.

For reference, my MM 2.1L M42 has less than 5k miles on it and it weeps oil like crazy (1qt / 1000 miles). I am running Castrol 10W-60 TWS oil which is an awesome oil (damn well better be for $18/L), but it weeps like a motherfucker. I am switching back to Castrol 15W-50 since it doesn't leak nearly this much.