M42 no oil after rebuild

[Car Addict]

I just finished rebuilding my m42 all new gaskets, o-rings, cleaned up the mess under the intake, rebuilt the power steering pump, a/c compressor, and all the timing components. I would also like to state this is not the first time i have rebuilt a BMW motor, with having successfully rebuilt an m62b44, s52b30, m20b25, and an s62b50; however this is the first time i have had a serious issue upon firing.

I have NO oil flow.

She cranks over fine did that a couple times for in total about 2 minutes plugged the fuel pump fuse back in fires up but all you heard was the tappets clacking away and the oil light stayed on, shut it down after 10-20 seconds. pulled the fuel pump fuse and removed the oil filter cover, cranked the engine and nothing, no flow coming in or out of the filter housing.

I am next going to remove the lower oil pan and check to see if the oil pickup screen is clogged, and what the upper pan gasket looks like to see if that shifted.

any help would be GREATLY appreciated thank you.

[bmwman91]

The M42 has been known to have bitchin' problems with oil pump priming after a rebuild. Did you pack the pump gears with grease prior to reassembly?

You might try pouring some oil into the center tube thing in the filter housing to back-fill the pump. It needs a little oil to fill the air gaps between the gear teeth.

[TobyB]

Yep, I had exactly your problem, altho I never started it until I saw pressure...

The oil filter housing has 'backflow' valves that have a significant
cracking pressure, and getting a dry pump to prime took several tries-
eventually, after cranking it with the filter cover off and the bolt in,
it splurted out an ungodly amount of air and oil, and promptly redecorated
the ceiling with 15-50. But that was after taking the oil filter housing off,
and cranking it that way until spunked me in the face.
I had taken the pan off, the filter housing off, but had not taken
the pump apart, so it must have dried out completely.

I wonder how they did it at the factory?

t

[Dj Buttchug]

The M42 has been known to have bitchin' problems with oil pump priming after a rebuild. Did you pack the pump gears with grease prior to reassembly?

You might try pouring some oil into the center tube thing in the filter housing to back-fill the pump. It needs a little oil to fill the air gaps between the gear teeth.

Yep you gotta either pack that bitch with a bunch of assembly grease or try and back flow it if you've already built the engine.

[Car Addict]

THANKS again everyone. after dumping in almost 2 gallons of oil and taking out the spark plugs and cranking for 10, 6 second cycles the pump came to life and started to burble out air and oil. slapped everything else back together now she is purring along just fine.

Obviously i will be draining the oil pan and refilling to the proper level.

[bmwman91]

Yep you gotta either pack that bitch with a bunch of assembly grease...

Wait, you were there the other night?????

[bmwman91]

THANKS again everyone. after dumping in almost 2 gallons of oil and taking out the spark plugs and cranking for 10, 6 second cycles the pump came to life and started to burble out air and oil. slapped everything else back together now she is purring along just fine.

Obviously i will be draining the oil pan and refilling to the proper level.

Nice! So you just way overfilled the crankcase with oil to try to get the level up closer to the pump? Good call on pulling the plugs, that makes the starter work a lot less hard and reduces the dry friction on a lot of things in the bottom end.

[TobyB]

I like the overfill trick- that makes good sense.
Glad it primed. I was pretty freaked when mine
didn't, too.

Don't be too surprised if your lifter(s) get noisy for 20 minutes
or so- that air can get pumped into them, and then they
clatter like crazy.

t

[roguetoaster]

I like the overfill trick- that makes good sense.
Glad it primed. I was pretty freaked when mine
didn't, too.

Don't be too surprised if your lifter(s) get noisy for 20 minutes
or so- that air can get pumped into them, and then they
clatter like crazy.

t

Saw a neat video of someone rebuilding a 944 cylinder head. He put the lifter (upside down) in to a jar with oil and applied vacuum which primed all of the lifters quite effectively. He also indicated that you can detect potentially bad lifters by pressing down on the "button," and if it takes excessive force they may be bad.

Skip ahead to about 4:30 https://www.youtube.com/watch?v=5GWBrsGTR2s