I need a little help thinking through something odd that happened the other day. The car's history as it pertains to this set of issues is that we put a rebuilt starter unit on the car about two years ago, and have had no starting issues of any kind until now.

The battery voltage and current have been checked to exhaustion. The battery is new within the last 3 weeks following the death of the old one during the first cold snap of this winter. I've verified my charging voltage (13.9 at idle, according to the tester Advance used when they installed my new battery) and have checked with my own multimeter to my satisfaction. The posts and clamps have been cleaned and firmly fastened.

The car currently has its summer oil in - Rotella 15w40 dino - I'll be putting something lighter in for the winter sometime over Thanksgiving. Last winter was milder; we only had about two below-20 days all year and it wasn't an issue. So cold/thick engine oil is definitely a factor in this particular case.

All six glow plugs are brand-new Bosch plugs with less than two months of use on them.


Now, my problem:

We experienced our first dramatically colder weather event of the season last weekend - the car sat for well over 24 hours in 15-20 degree air temps with 4 inches of snow sitting on top of it; at the time of my start attempt, the air temp was 19 degrees.

After running the glow plugs a little longer than normal, to give me a better shot at this start (Which shouldn't have been this hard; I did it last winter a few times with no issues). Turned the key and heard a noise like you'd expect to hear if the starter teeth and/or flywheel teeth were damaged or rounded off to the point that they were crunching against each other instead of engaging each other. It wasn't quite such a dramatic noise; it didn't sound like they were ripping each other apart - but obviously the engine didn't engage.

So, after a brief panic moment (I had a friend with me; we were on our way to a concert) - I re-glowed for luck and retried it - the thing engaged perfectly. Engine started with no more difficulties. Engine wasn't even THAT hard to turn over through the thick oil; starter speed was reduced a little bit by the cold and the oil stiffness, but not significantly enough to sound like it wouldn't start.

The worst-case scenario here that I can imagine is that I either have a starter tooth broken (relatively easy fix in that the starter is all that has to be replaced) or a damaged place on the flywheel. I see this as a possibility... but also find it hard to believe it likely. I can't see that the failure of this thing can possibly be coincidental with the first frigid weather the car has seen in 11 months.

I'm wondering if it's possible that the starter gear either was moving slowly (due to thick lubricants in it? not sure about my understanding of starters) - and was already spinning too fast to engage the flywheel without grinding the gears when they finally reached the meshing point - or else, possibly the gears meshed, the starter suddenly hit a wall of hard-to-rotate-engine due to my oil thickness and the extreme (for the conditions it had been seeing) coldness, couldn't spin the engine over a complete revolution in those circumstances, lost its momentum, and retreated just far enough to disengage the flywheel and then got back up to speed and tried to re-engage.

Are either of those cold-related situations likely explanations? Or am I facing flywheel/starter tooth trouble and this was my warning?

I'm paying careful attention to it; we charged the new-from-Advance group 49 1000/850CCA battery up with our trickle charger just to be sure it was completely topped up from the factory charge, and I'll listen to the thing when I crank for any trouble for the next few starts. Preceeding and succeeding this event, I haven't heard any unusual noises at startup at all; I always listen closely and I certainly haven't heard anything that sounded like gears clashing or teeth getting crunched until now.

If I'm panicking, it's just because I don't want to have a major repair (flywheel) now. I'd rather know what's going on than keep guessing until it leaves me starter-less.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL