Hello all,
I posted last week about a strange bolt near my alternator and upon investigation it appears as though it is what is left of the belt tensioner.

I have a 1985 300SD with two belts around the water pump/alternator. I realize I will need a new adjusting nut and screw, but I cant seem to find a picture of the adjusting screw so I am not quite sure if the small tensioner wheel is a seperate piece.

Also, in reviewing the procedure for belt changes at http://mb.braingears.com/126_DISC1/program/Engine/617/13-340.pdf
it looks like there is a tension measuring tool. Is this something that is absolutely necessary, or something that is often ignored during belt replacement (I realize the belts have to be reasonably tensioned).

Sorry for the long post, just wondering if changing the belts is something I can do at home, or best left to a mechanic/dealership.

Thanks

I'm not quite sure which part you are referring to, but this is the adjuster nut:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41WU1DADWK&year=1985&make=MB&model=300-SD-002&category=All&part=Alternator+Adj.+Nut

and this is the adjuster bolt:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41WU1DADWK&year=1985&make=MB&model=300-SD-002&category=All&part=Alternator+Adj.+Bolt

this is the alternator bracket with the adjuster "bracket":

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41WU1DADWK&year=1985&make=MB&model=300-SD-002&category=F&part=Alt.+Mount+Bracket

I've never used the tensioner tool, if the belts are too loose they will slip.

Sorry about the explanation, or lack there of.

I guess I am trying to ask if the tensioner bolt is an L-shaped piece with the tension wheel screwed on the short end of the "L" ?

Sorry if this is another lackluster explanation, but this is the only way I can visualize the tensioner working as I dont have an actual one to look at.

Thanks again

Look at this photo:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41WU1DADWK&year=1985&make=MB&model=300-SD-002&category=F&part=Alt.+Mount+Bracket

I believe this is the L-shaper piece you are referring to, note the "tension wheel" installed in the slot of the bracket.

The small "geared" washer that is on the bolt is welded to the bolt.

http://www.performanceproducts4benz.com/productpage.aspx?pid=100678

Your bracket should look like this

http://www.performanceproducts4benz.com/productpage.aspx?pid=100688

click on the "Buy parts" at the top and Phil can get it for you

The tensioning gauge is not necessary. I just tighten the belts until a firm push on the widest expanse produces about a 1/4 movement.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car