Hello everyone! I have this posted in the vintage section too, but this place seems to be a bit more popular. I'm hoping someone on here can help me out. Here's my story:
I bought a '78 240D about three years ago. It ran great for about a year, and then it had a small electrical fire under the dash somewhere. We had to have the instrument cluster replaced, and the mechanic said the cause was related to a faulty fuel cutoff switch or something, which also got replaced. Sometime shortly thereafter, the car decided it wouldn't start. I replaced the starter myself, and it ran great again for about seven months, at which point it wouldn't start again.
Well, the symptoms were exactly the same as before, so I got a replacement starter for free since the other was under its one year warranty, and replaced it again. This time it only ran for about three days before the engine completely seized up and the battery exploded. I did do a search on this forum for starter and/or ring gear issues with 240D's, and saw a thread discussing the two variants of Bosch starters. It sounds like I may have received the newer model of starter without knowing any better and doing this to myself. I will have to go back to the auto parts store and see if they can elaborate on that.
Anyway, I got it towed to a shop, where they removed the starter, and instead of simply having worn down teeth, like the other times, this time the teeth were all mangled and twisted. Not good. The mechanic also said that the ring gear was damaged and needed to be replaced.
I want to fix this thing, but would like to know what the root cause of all of this is. Is it electrical and somehow related to the fire way back when? I think it might be since the battery literally exploded. Is the ring gear the problem? Personally, I don't see anything wrong with it (other than some metal shavings I figured came from the starter, and I realize these could be a major issue) but I have included a link to a photo of it so that maybe somebody here can tell me what they think of it.
Also, if I have to replace the ring gear, is there some kind of engine balancing issue that I have to keep in mind? And are there any good instructions you know of to replace a ring gear? I do have the Chilton's for it, and it gives instructions for removing the engine, and for taking apart the clutch, but anything else that may help would be appreciated. I've never attempted removing an engine, so I'm sure this will be a "fun" project.
Anyhow, I'll go into it further if you all have questions, which I assume there will be many.
Thanks!
Ring gear