Why is there a hole behind the alternator bracket?
 

My alternator shook apart a few weeks ago so I took the bracket off the side of the motor to be wielded and bent back the other night. As soon as I got it off a good cup full of sludge fell on the ground and the back of the bracket was filled with it. After blasting it with brake cleaner I found a 10mm hole in the side of the block, it was a smooth bore so I'm guessing mercedes put it there. Any ideas why it's there and is it ok for me to seal it?

Post a photo. I had my alternator bracket off, and thoroughly cleaned the block on a stand, but don't recall such a hole. Often holes or pads are in a casting for later machining for different accessories - say components on other side for British or truck markets, industrial engines and such. It seems unusual if the bore was machined smooth and it wasn't used. The cam chain tensioner installs somewhere around there, probably lower.

I'm guessing that they had some extra holes at the factory and needed to use them up. You know that the Germans wouldn't waste anything.

Dan

I'm thinking pics would be a good idea before you do any kind of sealing.

Trying to think what it could possibly be. The block heater is in that area but that would be open to coolant. Aft of that, there is the front bracket for the starter.

Sorry guys. The temp was dropping so I threw it back together. I talked to an old mercedes guy, and the best he could come up with is it was so kind of hole for inspecting the crankshaft. Filled it with the right stuff, no more leaks:). It went right through the block I could have sworn you could touch the balancers on the crankshaft with a long screw driver.

????????:confused:
Uhhhh, that's sounds crazy!!!!

There is a shield with bolt holes. There is pic of the 617 in my 84SD before I got it cleaned off at the link below.

http://www.peachparts.com/shopforum/diesel-discussion/341966-wife-said-sd-wouldnt-shut-off-led.html

well the leak stopped. i have no idea what they were thinking at the factory that day. maybe someone got a new toy and wanted to try it out? or maybe someone bored it out for camera or something to go in it.

we really need a picture of this next time you have it apart.

The fact that you have a smoothbore hole directly into your oil system makes me believe that its some kind of drain from the SD air cleaner setup and or inspection hole that required a rubber grommet, but ive never heard of such a thing in the side of the block like this, and just held closed via sludge for so many miles. Weird

hey i'v got a mystery leak too......started the day i put everything back together after tearing it all down......now it leaks less, must be gunking up, but its down there somewhere, i assumed on the main front seal, but maybe a bolt or something missing :eek: but i never could see anything...... :confused:

anyways, all the things on my list have gotten done, so soon im going to have to locate it and do away with it.....

Can you see the 'hole' in this pic?

most likely its a recess that is filling with oil from a leak at the chain tensioner above.

awesome pic, thank you !!!

i will definately help me locate my mystery leak, what a great view :)