240D alternator Block bracket....what a PIA - PeachParts Mercedes-Benz Forum

steeleygreg · #1 12-27-2015, 09:36 AM

Need to replace the alternator bracket which is secured to the block on a 83 240D. The FO had an alternator installed which the mechanic cross threaded the bottom mounting bolt. Result is having to replace an alternator every year due to the front bearing wearing out. The angle of the alternator housing over time changes dramatically which binds the bearing. This is due to an oblong hole which develops over time in the bottom mounting hole because the cross threaded bolt.

Can the alternator mounting bracket be changed on the block without removing the harmonic balancer ?

Greg

vstech · #2 12-27-2015, 02:21 PM

Oh wow... good question. I have a block on my shop floor, gimme a call.

toomany MBZ · #3 12-28-2015, 08:15 AM

If you're referring to the item circled, yes you can remove it without disturbing the balancer.

steeleygreg · #4 12-28-2015, 08:48 AM

Yes toomany MBZ, it is item 116 which you circled ! Please enlighten me as to how ? The only way I can see it working is by removing the pulley assembly off the balancer and rotating the balancer until one of the notches lines up with the front bolt of item 116.
Would love to hear a method for this ?

vstech · #5 12-28-2015, 09:14 AM

I did not get a chance to look at mine, but I don't see what the balancer would interfere with?

the bracket is bolted to the side of the block...

vstech · #6 12-28-2015, 09:15 AM

ah... I see now, there are 5 bolts holding it to the block... one is behind the balancer.

cfh · #7 12-28-2015, 10:21 AM

I vaguely recall having the same issue on one of my cars (with an om617) and I rigged up a bushing to take up the space ovalled-out space - took a small piece of sheet metal and shaped it into a half-circle by hammering it around a bolt and crammed that in there around the bolt. Not a first-class repair but it has lasted several years.

If you can weld, it might be feasible to weld some metal into that spot and drill and tap it out. I don't weld though and have no idea how difficult it might be to do that kind of repair with the tight space constraints.

vstech · #8 12-28-2015, 10:29 AM

Quote:

Originally Posted by cfh

I vaguely recall having the same issue on one of my cars (with an om617) and I rigged up a bushing to take up the space ovalled-out space - took a small piece of sheet metal and shaped it into a half-circle by hammering it around a bolt and crammed that in there around the bolt. Not a first-class repair but it has lasted several years.

If you can weld, it might be feasible to weld some metal into that spot and drill and tap it out. I don't weld though and have no idea how difficult it might be to do that kind of repair with the tight space constraints.

his problem is it's an aluminum bracket... so, welding it would still require pulling it out to get it repaired.

Phillytwotank · #9 12-28-2015, 11:38 AM

SteeleyGreg the answer is NO. Benz there done that.

steeleygreg · #10 12-28-2015, 12:25 PM

OK, I haven't started this project yet, but this is planned near future which needs to get done. Approx 2 years ago the balancer was off this engine as in the below pic's. This was performed because of a massive oil leak and both the seal and everything behind it had to be replaced from damaged caused when the vacuum pump exploded when the PO owned the car. Currently the seal does not leak The third pic is from another members named Squiggle Dog from a thread posted 2/10/2013 showing the pulley removed from the balancer along with the balance ring. Now Squiggle Dog's engine was a 617 from a 300SD which is a little different than the setup on a 616, but the notch cutouts in the balancer are important and potentially the key to this job ! I agree that pulling the balancer would make this job a piece of cake, but pulling it can opens up a can of wooooop-ass for from research a special cup tool needs to be used for alignment and to dowel pins will need to be replaced, plus the crank bolt will need to be tightened to it's 200 ft lbs.
In my 616 which is depicted in the first two pic's there is not a balance ring. The 1st pic shows the bolt which needs to be removed and is covered in oil. I'm wondering if general consensus is this job can be done by using the notches in the balancer, or is there not enough clearance in those notches to pass the bolt head through ? If it can't the I'll have to pull the balancer as well.

Stretch · #11 12-28-2015, 12:39 PM

Quote:

Originally Posted by cfh

I vaguely recall having the same issue on one of my cars (with an om617) and I rigged up a bushing to take up the space ovalled-out space - took a small piece of sheet metal and shaped it into a half-circle by hammering it around a bolt and crammed that in there around the bolt. Not a first-class repair but it has lasted several years.

...

I was going to suggest something similar =>

Remove the bracket - take it to your pillar drill / local machine shop and drill a larger hole. Make up an over sized bushing (or get one made up).

Delrin might even do the job (not as long as metal of course but hey...)

steeleygreg · #12 12-28-2015, 01:00 PM

I already have two replacement brackets which are in good shape and the bottom bolt holes on each show no signs of cross threading.

Using the bushing idea is interesting, but the oblong which develops over time is not in the bracket, but in the alternator housing itself. Exploring the bushing route, the cross threading changed the bore angle of the bracket. In that case how would the line bore be corrected with a bushing ? I thought about this for the past 3 years. Without welding and sealing up the hole, then boring it with a line boring machine and re-tapping the threads which that procedure might be cost prohibitive for a new bracket from the dealer costs about $250 and the two which I have wasn't near that price..
Here are two pics from an old alternator which was replaced on this car. This is what happens to the housing when the bracket angle is off.

toomany MBZ · #13 12-29-2015, 08:10 AM

I must have turned the engine to access one of the bolts that hold the bracket on, been long enough ago, can't remember.

t walgamuth · #14 12-29-2015, 10:01 AM

yeah, isn't there a cutout in the edge of the balancer for removing a bolt?

steeleygreg · #15 12-29-2015, 10:47 AM

Yes, the balancer has two cutouts on either side which are opposite of each other. Wondered if other forum members have used the same process to remove the 5th bolt successfully ?