1992 325si e36 sounds like a diesel truck - BMW Forum

rednazk · 07-30-2008, 10:27 PM

My son bought this 325is a few months ago, got it hot, cracked the head, bought a so-called used complete head off a "dismantler" that looked like it had been gone through...it was clean, had a new thermostat, looked like it had been milled maybe...He put it on and when it starts up, it sounds like a diesel. We pulled the coil wires and turned the starter over and no bad sounds. It's not a tapping sound, but like a loud diesel truck when started. We've only run it about 15 seconds total. It almost sounds like the valves are hitting the pistons, but we should have heard something in the turnover test. One curious thing, the head gasket metal rings looked liked they would almost hit the valves it was so tight but the gasket kit box had all the right numbers. Any ideas?

witeshark · 07-30-2008, 11:09 PM

Sounds like very bad pre-ignition knock. First, don't run the engine until the issue is fixed; it could cause piston damage. Next, have a very close look at the ignition and valve timing.

rednazk · 08-04-2008, 12:47 PM

pinned the flywheel, checked that both cams were square...no change in the diesel sounding engine while running. The only thing I can figure is the head was milled the valves are barely tapping the pistons and I need an oversize head gasket, unless anyone has any other ideas.

leoreyes69 · 08-04-2008, 01:35 PM

My nissan truck used to do that, it was the oil pump. If that helps any

rednazk · 08-04-2008, 02:02 PM

the oil is squirtin in my face with the valve cover off, and it ran fine before it got hot, but I'll check it

rednazk · 08-05-2008, 03:54 PM

A mechanic said the hydrolic lifters probably lost their oil charge and try running it for a while to load the lifters back up with oil...we're gonna try that

budget76 · 08-05-2008, 05:01 PM

Quote:

Originally Posted by rednazk

A mechanic said the hydrolic lifters probably lost their oil charge and try running it for a while to load the lifters back up with oil...we're gonna try that

I have probably the same problem, and my mechanic buddy told me the same thing. I've driven it 100 miles, and it's still there

I just picked up a lighter wieght oil to try, and if that doesn't work, i'll be allocating a weekend to install some new lifters.

Good luck.

rednazk · 08-06-2008, 08:19 AM

Didn't work...tonight we are going to put the old hydraulic lifters off the old head onto the "new" head to see if that quiets them down. The old ones were not soaking in oil like the book suggests, so we put them in oil for a 24 hr soak last night.

rednazk · 08-11-2008, 09:29 AM

Update: we put the lifters and cams back on the "new" head from the old head and they were still loud, after breaking and repairing a valve cover bolt and one of the spark ignition packs (that caused oil to leak into the sparkplug opening and foul the area) we started it up and it still sounded like a diesel engine. We drove it several miles and a small change. We stopped the engine for about 15 minutes and restarted it and wow, the diesel knocking was almost gone, just some moderate tapping now. The knocking started to come back a little but quieted down after a few more start/run/drive stops. Very interesting. I have no idea how the hydraulic valves choose to loosen/tighten up based on this history. Oh and we did put synthetic 20-50 in the engine and started it up and ran it a while before the new lifters went in. This did not solve anything. This may have helped but I think the oil pressure and spring pressure changes over starts/run/drive/stop sequence somehow is the solution. Very weird experience.

darkhorse737 · 08-11-2008, 09:48 AM

i'd advise you so check you oil pressure and measure that against manufacturer's specs. The root of your prob just might be low oil pressure

hydraulic lifters should'nt be giving you that prob, really. I've had experiences with sticking lifters though, and for these probs, i like to use a detergent oil additive to dissolve the gum deposits that may be causing the lifters to stick.

KCRanger · 09-29-2011, 11:30 AM

I know that this thread is old, but I am new. What was the final outcome or what was the problem? I have an 87 325e 2.7. I have heard that this may be something to do with the air/fuel mixture.

Jack Dabsy · 09-30-2011, 03:03 PM

Engine timing I think lol

jimboG · 09-30-2011, 03:25 PM

Hi I have a 1987 BMW 535i . the car stopped running, just puttered out and now wont start. No spark at the plugs and the transmission cm light comes on and flashes realy quick and then stays lit. Ive checked both crank sensors and they are good, the main relay tests fine at the fuel injectors . the AFS is good, im getting power to the ecu. THIS THING IS DRIVING ME NUTS . I took the car to a european car specialist, and he charged me 45 .00 to tell me it was my crank sensors so I replaced them and STILL NO SPARK. QUESTION! can the TCM kill the motor if its bad? ANYBODY PLEASE!!!!

Jack Dabsy · 09-30-2011, 03:29 PM

Electrical my friend... Maybe the ECU has given up on you or just a poxy relay...
Cannot actually diagnose without being there mate...