Starter puzzle - PeachParts Mercedes-Benz Forum

Stevo · #1 07-13-2006, 02:06 PM

Last weekend I bought a parts/fixerupper, "77",manual 240D, "clutch is out and it has a starter problem" So fixing the starter problem is the first thing too do. I can hear the bendex "whirling" but no chechie. Change starter out for a "know" good one (there was NO rear mount, which may or may not mean anything) Same thing, same noise, no change. I swap another good starter in...same thing. I bench tested all three, doesnt seem to be a bad starter. I turn the engine by hand and look at the ring gear, looks fine, battery is fine. Tried it with a "shim".

If the starter motor is good there are a whole range of possibilities. A friend has a 617 engine setting out where I will take some measurements of the relative position of the ring gear to the adaptor plate and do some comparing. I was wondering if anybody could come up with any ideas .....assuming the starter motor is OK
I bought the car for the engine and tranny (which was claimed to be good) So I will pull the engine anyway but it would be nice to run it first. Why isn't it catching any ring gear teeth? An "MB minded" friend came over and we both wound up scritching our heads

Starter seems good, wheeeer, no catchie

rrgrassi · #2 07-13-2006, 02:12 PM

How are the teeth on the bendix and flywheel?

Also, are there shims used for spacing? How is the starter hanging with out the rear mounts? Does the bendix housing angle down to the ground when it is mounted?

It sounds like either there is too much space between the teeth of the bendix and flywheel.

barry123400 · #3 07-13-2006, 02:22 PM

Just for the heck of it try to turn the flywheel with a screwdriver. It is unlikely but what if the flywheel sheared the bolts to the crank. In neutral you should not be able to turn the flywheel very easily with a screwdriver. Also have someone watch to see if the fan is turning. Or put it in gear and see if the starter moves the vehicle without the engine fan turning. I do not like the second test though as the flywheel may just be pushed out of the way by the force of the starter if it is disconected from the engine. Unlikely but worth a try. Costs nothing and may give you a clue as to what is really going on. Also have a look to see that the belhousing bolts have not either backed off or someone loosened them to do the clutch. Let us know what you find out as what you describe is a little strange.

Stevo · #4 07-13-2006, 02:50 PM

Quote:

Originally Posted by rrgrassi

How are the teeth on the bendix and flywheel?

Also, are there shims used for spacing? How is the starter hanging with out the rear mounts? Does the bendix housing angle down to the ground when it is mounted?

It sounds like either there is too much space between the teeth of the bendix and flywheel.

All teeth look good, and I think the starter will work fine with that mount missing, for testing anyway, I will definetly replace the bracket it in the end. A mechanic friend said sometimes a spacer is used, I have never run across one.

Stevo · #5 07-13-2006, 03:09 PM

Quote:

Originally Posted by barry123400

Just for the heck of it try to turn the flywheel with a screwdriver. It is unlikely but what if the flywheel sheared the bolts to the crank. In neutral you should not be able to turn the flywheel very easily with a screwdriver. Also have someone watch to see if the fan is turning. Or put it in gear and see if the starter moves the vehicle without the engine fan turning. I do not like the second test though as the flywheel may just be pushed out of the way by the force of the starter if it is disconected from the engine. Unlikely but worth a try. Costs nothing and may give you a clue as to what is really going on. Also have a look to see that the belhousing bolts have not either backed off or someone loosened them to do the clutch. Let us know what you find out as what you describe is a little strange.

Berry

I did pry on the ring gear but not enough to turn the engine, good thought. Like I said, the only "clues" are "needs a clutch" (it doesn't appear to be the hydraulics) and no rear mount, which is, I think a "non issue". I will try turning the engine by the ring gear, it turned "normally" by the P/S pulley (sorry Greg

) this whole thing is odd and I spoz even if I had to buy a rebuilt starter too dispel the possibility of a "gaggle " of bad ones...I could use it "someday". I'm heading to town to take some measurements.

Thanks for the quick responses

barry123400 · #6 07-14-2006, 12:26 PM

Theoretically I guess you could have three starters bad in such a fashion that they spin up but do not seem to be engaged. The chances of that are almost astronomical though. This needs a clutch and multiple starters not able too engage the ring gear senario just seem too co-incidental in some ways. Common problem for both likely to some extent in my opinion. If you are still not sure perhaps pulling the glow plugs and putting the car in gear. Then with a few friends push the car with someone watching the fan. Better yet turn your engine from the front while watching the teeth on the ring gear for movement and see if the flywheel can be held back with a screwdriver in the ring gear if any movement. Again something seems very unusual here.

Stevo · #7 07-14-2006, 04:50 PM

When I pryed on the ring gear it turned all right but the f/w DID NOT, so I just got done pulling things apart. The clutch disc lining came down in many tiny pieces (gag) so it looks like the POs daughter really did toast the clutch

I have never had a ring gear come adrift. It looks good espically if it can be turned around where the corners of the teeth are like new. How is a new/old gear reatached?? super glue, JB weld

barry123400 · #8 07-14-2006, 05:09 PM

Most ring gears are heated really hot and installed on the flywheel and shrink tight as they cool. At least you found the problem. If your ring gear had a crack it would come loose for example. Have a very hard look at it. If you can get the ring gear back on with no heat and it is not cracked I would go grab a used flywheel. The balance should be checked in comparison to what you have if that approach is used. The other approach is to get another ring gear if the old one is cracked. Personally I like that choice as your original balance of the flywheel is retained. Make sure to make good marks flywheel to crank before pulling the flywheel. The factory marks are hard to impossible to find apparently. Excellent oportunity to have the flywheel surface ground prior to installing a new clutch as well. The bevel on the ring gear starter side may still be required to ease engagement of the starter drive. I would not reverse it without checking if it were found possible to reuse it.

Stevo · #9 07-14-2006, 10:10 PM

Berry

Well your suggestion of prying the ring gear to turn the engine made that "ah ha" moment

I also liked the "new ring gear option" but the guy at the machine shop where I have had work done in the past, said "if its lose on the f/w
then the f/w is n/g. (its lose) Then a friend stopped by for a game of crib, and mentioned he had an old ford where the ring gear was welded back on and re balanced. I wonder if that could be done? I will look again for a crack (broken) which would explain the lose fit.

Since there is no mark on the f/w and no mark on the one I have laying around, (which is out of a "later" 240D), I think I'l go for the "swap" option and be done. The replacement one looks fine. Thanks for the suggestions, not many (actually none) of the folks I talked too around here have heard of a "spun" MB ring gear.

Stevo · #10 07-16-2006, 08:53 PM

Just got it back on the road. Runs smooth with the replacement flywheel, clutch disc and p/p.

Thanks for the help

TwitchKitty · #11 07-16-2006, 10:21 PM

Congratulations on getting your car going, interesting problem too.

For future readers:

Test a starter before you install it. Hook up 12V and watch it spin. Watch for the drive gear to move forward to engage the ring gear. Be careful, the starter will jump when you put power to it.

Stevo · #12 07-17-2006, 01:39 AM

Quote:

Originally Posted by TwitchKitty

Congratulations on getting your car going, interesting problem too.

For future readers:

Test a starter before you install it. Hook up 12V and watch it spin. Watch for the drive gear to move forward to engage the ring gear. Be careful, the starter will jump when you put power to it.

Yah, after installing the second starter that I new darn well was good, I pulled it and tested all three and they all tested OK, they do "jump" when you put the juice to em.