Should My 6 OM617 Crank Pulley Bolts Have Washers? - PeachParts Mercedes-Benz Forum

Squiggle Dog · #1 02-04-2013, 02:20 AM

Today I removed the crank pulley on my 1980 W116 300SD with OM617 engine and noticed that none of the 6 bolts as pictured below have washers on them. Are they supposed to? The EPC shows a part number for the washers.

A couple of the bolts are rounded inside, so I planned to get some from a junkyard car, but wonder if I should get new ones instead. I think my local Ace Hardware has them in 8.8 grade, but something tells me I might be sorry using aftermarket bolts instead of ones from Mercedes. As for the washers, I don't know if they are needed or necessary. I'd probably get them from Mercedes.

Stretch · #2 02-04-2013, 03:13 AM

I'm not 100% sure but I think the fixing material there is 10 grade stuff...

...are the washers at the dealer too expensive?

ROLLGUY · #3 02-04-2013, 01:22 PM

I don't remember seeing any washers on any of the pulley bolts that I have removed (there have been many).

Squiggle Dog · #4 02-04-2013, 01:33 PM

Thanks for the replies. Since mine did not have washers, and the pictures I see of the bolts never seem to have washers with them, I am wondering if they would be good to have, or a hindrance. I plan to use blue thread locker on them anyway, so I may not need washers (especially if they didn't come with them). I have seen some with washers, however, they have all been the hex-head type, not the Allen-style.

I might get some used bolts from a wrecking yard down the street to replace the couple that are rounded. I don't think it would hurt to install used ones... they are not high-torque and don't know if there is much danger of shearing them, though I know it happens. I don't mind getting ones from Ace Hardware if they are 8.8, correct length and pitch, and not a more brittle number like 10 or 12.

Stretch · #5 02-04-2013, 02:51 PM

Quote:

Originally Posted by ROLLGUY

I don't remember seeing any washers on any of the pulley bolts that I have removed (there have been many).

You got me worried - so I checked the FSM!

Chap 03-340 in the OM617a W123 section of the FSM clearly shows them on schematic on page 2 of the PDF - I know the subject vehicle of this thread is a W116 but it is the same engine (near as damn it)

whunter · #6 02-04-2013, 04:05 PM

300SD
W116.120

Has six grade 8 Allen screws with spring washers, mounting the pulley on the harmonic balancer.

The original early factory Allen screws where at start of production grade 10, due to broken screws MB issued an urgent technical service bulletin changing to grade 8 fasteners.

Screw, quantity 6
MB# 000912008203
http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&command=DWsearch&description=000912008203&x=12&y=11

Spring Washer, quantity 6
MB# 000137008204
http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?SUPERCAT_FLAG=&make=&please_wait=N&forumid=&threadid=&command=DWsearch&description=000137008204&I1.x=15&I1.y=9

.

ROLLGUY · #7 02-04-2013, 04:32 PM

Now you guys have me wondering as well. I may have to check the spare engines I have laying around here....Rich

Squiggle Dog · #8 02-04-2013, 05:21 PM

The screws on my 1980 W116 300SD are all grade 8.8, no washers. I removed some from a 1980s W126 300SD, also grade 8.8 and no washers. I checked out Ace Hardware, and though they had some that were identical, they were indeed grade 12.9, so they might shear.

So it appears I've got to get some spring washers. Maybe new bolts, too...

P.S. If you check out the "Marcedessauce" site, Kent sells grade 12.9 bolts for use on the crank (pictured above). He seems like a smart guy, but maybe not the best thing to use?

cjbrown · #9 02-04-2013, 06:48 PM

All six of mine sheared off on my pick up trip from South Dakota. Got within 200 miles on the 1300 mile trip and I heard a clanking noise and then the warning lights came on. Main pulley had sheared off. I got a AAA tow the rest of the way home, they billed $1500 for the flatbed tow.

The were sheared off flush so a quick drill and ez out and had them all out. ACE replacements, but I don't know what I put in there, probly 12.9.

A lot of people get confused about metric high tensile bolts. While they are stronger they are more brittle and particularly when used in a shear load they can...shear off. LOL.

Spring washer will keep them tensioned, but locktite is fine too.

I wondered why I heard an odd clanking noise every time I stopped at a rest stop or for gas. The diesel is noisy anyway, so didn't pay enough attention.

Have put about 5K miles on the car without issue, so I'm not sure it's that critical. As long as there are six of them in there and they are tight. The rad has to come out to get to them.

qwerty · #10 02-04-2013, 07:27 PM

Quote:

Originally Posted by cjbrown

A lot of people get confused about metric high tensile bolts. While they are stronger they are more brittle and particularly when used in a shear load they can...shear off. LOL.

A lot of people get confused about shear and tension loading as well. One sometimes prevents the other.

Squiggle Dog · #11 02-04-2013, 09:00 PM

I left my radiator in place in my W116 300SD to get the six bolts off the pulleys and the harmonic balancer off. Today I pulled off four bolts from the crank of a W126 300SD and didn't need to remove the radiator, either.

So far I don't see any point in removing the radiator other than to keep from damaging it, but so far a flattened cardboard box has done the job. I even have the crank seal and spacer ring off. Sadly, the spacer ring was fused to the crank, so I had to remove the aluminum top cover to get it off. Now I am noticing that one of the threads on the aluminum cover is stripped! Back to the wrecking yard tomorrow.

Stretch · #12 02-05-2013, 02:34 AM

Thanks for clearing up the confusion Roy!

Squiggle Dog · #13 02-05-2013, 08:56 PM

Okay, I'll be a good boy and use new bolts and washers. I had to remove the harmonic balancer from a junkyard car so I could get to the upper seal cover... one of the pulley bolts sheared off as I was loosening it, and the rest of the bolts looked bent.

Squiggle Dog · #14 02-06-2013, 04:44 PM

FYI: The bolts now provided by Mercedes-Benz are grade 10.9, not 8.8 like the originals. Let's hope they hold up.

Squiggle Dog · #15 02-09-2013, 12:24 AM

A footnote in the OM617 engine manual reads:

"Since January 1979, the fastening screws (17) for pulley and vibration damper on engine 617.950 are inserted without washers (18). On engines 617.951/952 from start of series."

I wonder why the change?