Couple thoughts on E46 M3 engine failure

Alex Mc · #1 (**permalink**) 05-05-2002, 11:24 AM

Just thought i'd drop some expertise/speculation on the bottom end failure problem. Anyone very familiar with the E46 M3 internals please comment.

The problem with S54 motors burning up rod bearings, and occasionally tossing a rod is not really all that new to the design. Although it is an entirely different motor, the bottom end is very similar- almost identical- to the predecessor E36 S50/S52 Euro motors, which were also notorious for bottom end problems with rod bearings.

I personally read all 25 accounts on bimmerforums, and found it quite surprising, but at the same time i didn't. One thing i did want to say, is that when i rod bearing goes, it doesn't always go right now. One day your charging through an on-ramp and the oil pressure drops in the block for just a moment and there goes the skin off of a rod bearing. This doesn't mean that it's going to go right away though.. several people claimed they weren't driving the car hard or fast when they heard the ticking noise, then all the sudden she went. That would be the rod bearing slowly wearing through it's shell.. then, several engine hours later when you're cruising on the highway the bearing finally mills down through the copper, seizes, and spins. You would have a much more violent shutdown (throwing a rod) if this were to happen instantaneously like on the track (ask me how i know

).

Now, the exact reason why this has been happening is not known, but our best guess is the lubrication design in the block. The S50/S52 Euro motors have a dual-gallery layout in the block- one feeds rod bearings, and everything else, while another feeds the pistons sprayers. This design troubles to keep OP constant and the first area that gets robbed in the event of a pressure loss is the feed to the rod bearings (#3 in particular.. kinda like how S14's always lose #2 first) All other BMW inline 6's use a single gallery system, and spinning rods happens once in a blue moon on those engines. So, maybe it's the lube design, maybe not.. i guess BMW may or may not fess up to the real problem in the future.

Camel · #2 (**permalink**) 05-05-2002, 12:45 PM

The E46 M3 engine uses thicker oil now.... problem solved... they say.

Alex Mc · #3 (**permalink**) 05-05-2002, 01:11 PM

Quote:

Originally posted by Camel
The E46 M3 engine uses thicker oil now.... problem solved... they say.

Yes, i've read that. But i doubt that will burry the problem entirely..

I also noticed that someone saw there have been 2 revisions to the crankshaft in the E46 M3, it'd be interesting to find out what those revisions were.

napalm.one · #4 (**permalink**) 05-05-2002, 02:55 PM

I've been reading posts from several forums concerning the E46 M3 engine failures for some time now, and I have yet to find answers to my question. IS THIS engine failure issue a potential problem in ALL M3's? Or is it a rare poduction/material defect that are found in a limited percent of cares produced? Finally, has BMW found a way (whether material or design) to prevent these problems from occuring in newer production cars? PLEASE if anyone knows answers to any of these questions, please reply!

Kevin · #5 (**permalink**) 05-05-2002, 05:32 PM

I remember reading about the problem a while ago when the E46 M3s were first comin out. I think there was a delay in shipping the cars to make revisions to the bottom end. I remember that they were mainly having problems with the #3 rod bearing.

I didn't realize that they have oil sprayers. Do all the BMW I6s have oil sprayers?

Alex Mc · #6 (**permalink**) 05-06-2002, 06:13 AM

Quote:

Originally posted by Kevin
I remember reading about the problem a while ago when the E46 M3s were first comin out. I think there was a delay in shipping the cars to make revisions to the bottom end. I remember that they were mainly having problems with the #3 rod bearing.

I didn't realize that they have oil sprayers. Do all the BMW I6s have oil sprayers?

Yes, they all have sprayers.

The thicker oil supposedly fixes the problem, but not only is that a half-ass way to fix such a serious problem, it's also power-robbing. Going to an oil weight that heavy is probably a 5hp loss or so..

Anyone know what the crankshaft revisions were?? That'd tell us a lot.

BMWGuy206 · #7 (**permalink**) 05-06-2002, 07:01 AM

Not much I can say about the S54 crankshaft.

The S54 crankshaft is forged steel with 12 counterweights and a 91mm stroke. The crankshaft is supported by 7 (60mm diameter) main bearings with 49mm diameter connecting rod journals.

The "thrust" bearing is a multipiece shell assembled as a unit and is located on the number 6 main journal of the crank.

pete · #8 (**permalink**) 05-06-2002, 08:53 AM

hey alex... you know, an aftermarket company could probably make a dry sump kit that would help curtail any issues of oil starvation...

is it oil starvation because of pan design or is the pump underrated?

BMWGuy206 · #9 (**permalink**) 05-06-2002, 11:29 AM

I dont believe its the pump or sump design. The S54 uses a semi-dry sump system very similar to the S62.

I think its the materials used on the con rod bearing or design feature.

Basically the tolerances are so tight, there is no room for error. KNOCK KNOCK.

roozy · #10 (**permalink**) 05-06-2002, 11:32 AM

that bmw changed the oil and the problem got worse...here are 2 links that go in depth about the problem and a some owners with blown engines talkin.

-Owner with blown engine

-3 E46 M3 engine failures at Road America/ Windy City DE

Alex Mc · #11 (**permalink**) 05-10-2002, 09:12 AM

Is the sump in the rear of the motor on the new S54 M3 engine? Can someone please confirm this? I'm almost certain it is, it has to be..

Also, i think the switching to a heavier weight oil is a hell of a cheap fix, and probably not even a good one. First off, if the pressure is going to drop and #3 is starved, a thicker weight oil might buy you a few milliseconds, but hardly a true fix. Also, i'd be willing to be there's a 5-10hp loss with that thick as hell 60W oil.