Author Topic: M42 Diesel engine noise (Read 2865 times)

rsdvr6 · « **on:** November 17, 2011, 06:14:23 PM »

My 1991 318i is making a Diesel sound. I have been reading forum after forum, thread after thread about the potential causes to this sound from the M42. The issue is no one seems to know the remedy. I have replaced the tensioner for the timing chain. I have replaced the lower and driver's side guides. I have replaced the head (my own fault for trying to see what the problem was and the car died and would not start again...bent valves). I have pulled apart the camshaft hydraulic lifters (intake side) and replaced it with a known good set. Now I am just frustrated. The sound is greatly diminished but is still the same "clacking" noise. It sticks with the revs and as they build the noise "seems" to diminish even more but obviously that�s just engine revving over it. I have thought about the oil pump but after seeing oil all over the cams, lifters and the tensioner I ruled it out. Another minor question I have not been able to get an answer too, how do I check oil pressure? Where is the pressure sensor? I purchased this car about 6 months ago and have yet to get to enjoy it. That will ok if I can get it running properly. I guess the next step would be to just rebuild the engine all together. Maybe get with Teddy or/and Court at MM and build one of their monster engines.

victor.askew · « **Reply #1 on:** November 17, 2011, 09:03:22 PM »

The oil pressure sensor is located on the lower left side(driver)of the engine block directly in behind the oil filter housing. I am also chasing a RPM related ticking after a cylinder head replacment completed last wkend. The lifters, the fuel injectors are my major suspects at this point. What wt oil are you using? Heavy, thick oil will cause the lifters to click loudly.
Good luck.

DesktopDave · « **Reply #2 on:** November 18, 2011, 05:49:04 PM »

Did you check the timing chain idler gear? They were removed in later M42's due to bearing failures.

rsdvr6 · « **Reply #3 on:** November 18, 2011, 07:22:57 PM »

The oil is Castrol 10-40, I live in Colorado so this seemed like the best choice. As for the idler gear, I checked and inspected all the timing chain components and this one had no visible damage. It also passed a load test (little difficult to do but none the less the gear was able to take a load and still spin freely). I have thought about the injectors too because the noise seems louder at the intake. Can fuel injectors really make this type of noise? It seems seriously loud for something that does not truly "move". The lifters I suspected and changed out so I guess the injectors are a way to go. I will keep you posted on the progress.

DesktopDave · « **Reply #4 on:** November 18, 2011, 08:00:41 PM »

Here's a tip...you can test injectors the old-fashioned-way with a long screwdriver. Just set the blade on the injector & listen at the handle. I agree with you, I don't think that's the cause.

10w40 should work well. I'm running it now myself, couldn't find any full synthetic 15w50 for the winter.

rsdvr6 · « **Reply #5 on:** November 18, 2011, 09:10:31 PM »

Great tip, I used this same "stethoscope" procedure when listening to the timing chain upper and lower covers and the lifters. The more I dig into this the more I am just at a loss as to the cause of my engine noise. I need to continue to diagnose the whole situation. When I bought this car I told myself I wanted a project car so here I go. LOL!

rsdvr6 · « **Reply #6 on:** November 20, 2011, 06:25:59 PM »

LIFTERS! After all the diagnosising, thinking it was an oil supply issue and also reviewing the timing. I started looking at the lifters and how some of them did not seem move. I continued my research and came to a consensus that if it is not the lifters it had to be my timing. Once I reviewed my old head and the cams, lifter buckets, and lifters I knew there was an issue with the lifters. Thank God he knows what he is doing. LOL!