M42 guys...i need help please

[christophbmw]

hey, i havent posted here in awhile but here is the deal:
I just pulled the motor and tranny out of my 318is and i did a COMPLETE rebuild new everything (valjob bearings every seal...e.t.c...). anyway i have everything back together and i started it and it had a terible knock (ive built many motors so i just figured to give it a couple minutes cause its probabally just the hydralic lifters). anyways the noise didnt go away, it sounds like a diesel. you cant drive it, i have a engine code for the "O2 sensor control" it wont rev past 2500rpm. anyways the fuel pressure is ok, the oil pressure is fine, i rechecked the cam timing, and the compresion and everything is fine (and no nothing fell in the cylinder and is knocking around).

ive run out of options, my latest theroy is that when i put the head gasket on (i was in a hurry) i plugged up the high pressure hole for the oil going to the head and the lifters are not getting pressurized causeing a terrible knock. i am going to pull the valve cover tommorow and start it to see if oil sprays out. anybody have any ideas? any help is much appriciated, thank you.

[kowalski]

where is the knock comming from? and did you take the motor all appart? like bare block appart? did you assemble it properly? use a stethiscope and find where the knock is comming from, and go from there

[christophbmw]

i took everything apart except the pistons, i did not take them out, i used red line assembly lube and the knock is coming from the head (i know this sounds dumb but it is very loud and very hard to pinpoint where it is coming from).

[kowalski]

could a valve be dropping and the piston is hitting it up? do a compression test. pop off the vvalve cover and take a look arround. how heavy is the knock?

[hamann318is]

Is the timing chain super tight?

I know my motor was acting like a desiel when I had the head rebuilt. It look a minute for the chain tensioner to tighten, and after it did, the motor ran fine. I wonder about the 2500 rev-limit though.

[christophbmw]

Is the timing chain super tight?

I know my motor was acting like a desiel when I had the head rebuilt. It look a minute for the chain tensioner to tighten, and after it did, the motor ran fine. I wonder about the 2500 rev-limit though.

so when your chain hit it sounded really loud too? cause i was thinking it might be that to. and on the 2500 rev limit: i think the ECM is getting a signal from the knock sensor and not letting it rev, funny though i dont remember ever seeing a knock sensor. does the M42 have one?

[e9nine]

No knock sensor on the e30 m42.
Is your oxygen sensor plugged in indeed (even though I don't see how this would affect revs). Check engine light is usually related to emission related issues. It can't hurt to double check your assembly of fuel and vaccum lines as well

[hamann318is]

so when your chain hit it sounded really loud too? cause i was thinking it might be that to. and on the 2500 rev limit: i think the ECM is getting a signal from the knock sensor and not letting it rev, funny though i dont remember ever seeing a knock sensor. does the M42 have one?

I replaced the chain tensioner which you have to expand by releasing the spring. The chain was fairly tight then, but the motor needs to fill the tensioner full of oil. Once I got the motor to fire, the motor sounded like it was seriously messed up. It would run for a few seconds sounding like a very poorly running desiel. The motor would knock and shake and it sounded awful. I started it a few more times and attempted to rev the motor during the starts. It began to sound more and more normal, and after I let off the accelerator, the motor was running fine.

My guess is your problem lies somewhere in your timing chain system.

[christophbmw]

hey thanks for all the help, i changed the chain tensioner and this time i looked up the proceedure and did it right. you where right when you install it you have to push on it to unlock it, well my chain is working fine now. i also looked up the proccedure to bleed the hydralic lifters (never heard of such a thing). anyways that was a failure but the noise went away slightly, i think its just the two center cylider lifters, im thinking they went bad because i had the engine running for 15 min and the lifters had no oil in them, now that i blead the system the ones that survived that first 15 min are ok and the others are junk and making noise. DAMN! ill figure it out thanks for the help.

[Rob]

do you have a link to this 'bleed the lifters' thing?

[christophbmw]

do you have a link to this 'bleed the lifters' thing?

i work at european auto repair shop and we use a program called "alldata", this is where i got the article, i will try to see if i can post it later. like i said.....ive never heard of "bleeding" the lifters but it says it has to be done. im thinking the oil might have drained from them when i had the motor upside down on the enginge stand.

[m20e34]

i work at european auto repair shop and we use a program called "alldata", this is where i got the article, i will try to see if i can post it later. like i said.....ive never heard of "bleeding" the lifters but it says it has to be done. im thinking the oil might have drained from them when i had the motor upside down on the enginge stand.

I say run the engine more. You aren't going to make bad lifters worse, and they might pressurize with some time.

[kowalski]

hmm bleeding the lifters eh? i used oil flush and it worked really well to silence the lifters.... i have like 20 sitting in my room if anyone needs them. they are all originals, not aftermarket so they made of the good sheit.

[christophbmw]

I say run the engine more. You aren't going to make bad lifters worse, and they might pressurize with some time.

ya i have to go shopin with the old ball and chain today but tommorow i was going to run the engine more, and pull the valve cover off and try to push the lifters down and force the air out of them. i was even thinking about just driving the car but it wont rev past 3500rpm, i think it is the computer limiting the rev's because it feels the same way when i used to hit the rev limiter at 6500.

[christophbmw]

i found the problem. im a dumbass for not reading instructions, on the bentley it says there was a oil check valve in the block and if it wasnt installed properly that the oil to the head will be restricted, well i geuss part of it fell out and i ended up pulling the head this weekend and installing a new one and it runs fine now. just to let you guys out there know when you rebuild your M42.......READ THE INSTRUCTIONS it save time and $$$$.