Horrible grinding noise on startup.
 

Ok. So My 240D has a serious starting problem. About 50 percent of the time when I try to start the starter doesn't engage whatever it's supposed to engage on the motor to actually turn the motor. I assume the teeth on the "thing" on the motor that the starters teeth mesh with are broken. There's a horrible grinding noise and the starter just spins freely. Dont know what that part would be called, "ring gear" perhaps?
Anyway, I'll have to pull the motor to get to this. Assuming I do that what's involved in replacing this part? Can it even be sourced and what would be cost be?

- Peter.

I believe the starter spins the flywheel which has hardened teeth. So the grinding you hear is probably the teeth on the starter being ground because they aren't fully engaging with the flywheel teeth. I removed the starter on my 240 when it went bad; I found it easier to remove the air filter assembly than the steering arm (I forget the exact part name) bolt as recommended in the Haynes manual.

Check this out: http://www.peachparts.com/shopforum/showthread.php?t=167766&highlight=cold

I bought a 240D with a "bad" starter and it turned out too be the ring gear was spinning around the flywheel, Your problem might be missing teeth on the ring gear. I pulled the tranny. The flywheel, I exchanged with a parts car one I had. A ring gear can be had new and replaced on your flywheel.

Go for the starter first- easiest and cheapest to replace.

I had a similar experience. It was the ring gear. The ring gear always stops in a few favored positions, so the starter always engages into these same few spots (the crank always stops on a compression stroke, so, depending on how many cylinders, you get a couple of of "favored" locations). As a result there is higher wear in these spots, and, eventually the wear can cause the starter to lose its abilty to transmit torque to the ring gear as teeth break off. Once all the teeth in each spot are broken off, the starter won't do anything. I had a manual 240D and I could put it in gear and force the engine to turn past these favored spots and get the car to start, but my wife didn't like this ritual. So, I had the ring gear replaced. You have to drop the transmission and remove the clutch on a manual, to get to the ring gear. It is press fit on the flywheel. I changed the clutch wear parts (throw out bearing and clutch plate and pressur plate) while there was, literally, free access even though the clutch was still healthy at the time (about 175,000 miles).

So, I think you have a ring gear failure. Good luck, and I hope this helps. Jim

Jim, thank's for that input. It does seem very like my situation. Just so that I understand what you are saying. Do you mean that the ring gear is in the transmission itself? or that you just have to drop the tranny to get to the back of the engine where the ring gear is located? Also. Would it make sense to swap out my starter for the spare I have and see if this affects the issue?
- Peter.

Peter,

The ring gear is literally that, a ring with gear teeth on its outer periphery. The ring is pressed on the flywheel, so, if you look at a picture of a flywheel you will see gear teeth on its outer periphery. So, you have to drop the transmission to gain access to the flywheel. I am assuming you are speaking of a 4 speed 240D, so you will also have to remove the clutch hardware to get to the flywheel and replace the ring gear. While you are in there, if the clutch is a few hundred thousand miles old, you might as well replace the wearing parts as sure as can be, once you put those old parts back in, one of them will fail and you will be back inside. More than half the cost if you have someone do this for you is getting access and putting all the removed stuff back on, so it is a significant savings to take care of the clutch while you are there. Good luck and I hope this helps. Jim

Thank's Jim. Yes, it's a 4 speed manual 240D. The tranny has 383000 on it and I'm pretty sure the clutch is on it's way out too so I think I'm going to have to baby the thing until I can hopefully get a house later this year with enough space to drop they tranny and do this stuff myself.

- Peter.

Remember, if you push the car in a gear, like third, and get the engine to roll over a few "teeth" on the flywheel, the starter will work fine. My wife thought that was a bit much. I used to just park on a hill, let the car roll forward a bit once the glow plugs had cycled, and then let out the clutch and turn the key, then put the clutch in and bingo! it worked every time. She drove the car half the time and thought that was unacceptable. You may find it works just fine while you are waiting. Jim

Jim. I was about to post asking you how you turned the engine without engaging the starter. Thanks for the update :)

Just so I'm clear. Are you saying that I have to turn the key with the clutch out? Surely that would cause the car to jump forward as soon as you engage the starter?

- Peter.

Peter,

What you want to do is use the car's momentum if you have it parked on a hill to turn the engine far enough so the broken teeth on the ring gear move away from the starter's pinion gear engagement area. Once you get the engine to turn just a little, you turn the key to engage the starter and you will find it engages like it used to, but, to avoid driving on the starter, you have to push the clutch back in. Or, you can just let it roll forward a bit, then let the clutch out with the car in third, and stop after about six or 8 inches. Then try starting the same old way. This will get you about a quarter turn on the engine, and should present a sound set of teeth to the starter pinion so it will work fine.

If you are parked on level ground, just put the car in third or fourth gear and push it forward several inches against the engine compression. Then try to start it. If you turn the engine over far enough to have the flywheel/ring gear present whole teeth to the starter pinion, the starter will function normally. And getting the car to move is no big deal, as this is how I always adjust valves - put it in third and pull the car towards me from the front, watching the cam lobes.

If you are on a hill with the nose up all this becomes more difficult since the reverse gearing is so high. It is still feasible but you need some room, not something you would attempt on typical NYC curbside parking on the street....

Good luck, Jim

Thank's Jim. I shall try what you've suggested. Unfortunately Phoenix is about as flat as a city can be but I'm sure I can figure something out.

- Peter.

You might manufacture your own slope by backing the rear wheels up some small ramps when you park. Steve

By the same token you can use this as a test. If you roll the engine over a little by pushing the car and the starter acts the same. It probably is the starter drive instead of the ring gear.
If this is not clear mention it and I will clarify. Hope it is just a starter drive. By having someone watch the fan blades you will be able to tell when it rolls over a little. The other factor is the almost 400 k miles or more involved perhaps. Everything wears with time and use.