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rkpatt 06-11-2006 11:35 AM

1983 300SD front crank seal house ratting
As I explore what has to be done to my newly purchased 1983 300SD , I have notice a rattling behind the front crankshaft pulley . With a flashlifght it looks like the a metal plate with 10 mm head bolts ( crankshaft seal retainer?) . What is strange is that there is only slight of oil leakage in spite of this being loose . Is there any way to tighten it up easily (vs removing radiator etc and removing the pulley ) ? - Thanks

rkpatt 07-10-2006 10:54 AM

I haven't driven the car since I posted the message because I was concerned about haveing major damage if something bad was wrond. Any feedback on this is appreciated .

Pete Burton 07-10-2006 11:03 AM

If you can't bend up a cheapo 10mm wrench to access the bolt heads, you'll have to remove a few things to get to it. The radiator is really easy to remove (my youngest daughter has done it). Make sure you mark the balancer before you pull it.

OMEGAMAN 07-10-2006 11:06 AM

I wouldnt drive it untill you get it fixed. Bend a cheap wrench or pull it apart and see what else is wrong. And while your there you should replace that seal.

dmorrison 07-10-2006 04:05 PM

The upper crank support unit has a sealant between the block, the lower oil pan and the piece. So to remove, clean and reseal the unit you will have to remove the radiator, the pulley, the balancer, the front seal and the front crank bearing. Clean the support piece. Use a sealant, Mercedes has this specific sealant. Mercedes part # A003 989 98 20 10. Also while your doing this you should replace the crank centering bearing and front crank seal.
Here's the bad part. Reinstalling the upper support requires a special tool. to align the upper half so it is centered on the lower half. This is so the front crank seal will not leak. I was able to borrow the dealers unit for this job. Can it be done without the tool? Probably. Just make sure the upper and lower edge where the crank seal goes are aligned as much as possible. The tool also centers the upper support to the crank shaft center. ( Sir tool does sell it M716-0014. go to the top and click on "Special tool" and go to page11, item 617-0014)
Remember to mark you balancer for reinstalling. Not 1-2 degree specific, just don't want it 180 degrees out. I positioned it as carefully as possible, aligning the 2 holes on either side of the shaft, and then drove the 2 small aligning cylinders into the receiving holes. Some of the small cylinder material may shave off as you install them.
While your doing all this work consider replacing all the accessories seals on the front of the block. Vacuum pump, Hydraulic pump (if SLS), Timing chain rail access bolts, TDC holding bracket bolt sealant. These are potential leak points and your there anyway.
Here is a post on the job I did on the 300TD.


rkpatt 07-11-2006 07:51 AM

Crank seal housing rattling
Pete - As suggested, I first will try to grind / bend a 10 mm wrench to get back in there to try to tighten things up and hopefully I wont have to go to plan B ( Dave's subsequent post ) to stop the rattling behind the harmonic balancer .

Dave - that post of yours on the crank seal stuff is great ( ) . It looks a little more complicated than I thought but manageable . Can you decribe what how special tool works so I can improvise . Do I also need a puller .


dmorrison 07-12-2006 04:30 AM

As posted consider a ground down Allen wrench to tighten the upper support. This will be the quickest fix. You may get a leak, eventually, but that can be fixed in time. Everything leaks, it's just a matter of what is acceptable.


I did not need a puller to remove the center bearing. It just came out with with my fingers. I figured you could use a couple of finely ground flat screwdrivers to wedge it out. It will just depend on the fit of the old bearing. With the age of our cars I'll bet it just pulls out. The Sir tool is available if it is tight.

The centering tool had a center hole that goes around the crankshaft. Then you press it into the opening. The outside diameter is used to align the upper support with the lower U shaped oil pan opening. If you are careful and meticulous you can probably align the 2 halves ( upper support and lower oil pan. The upper support moves, not the lower oil pan.) without the tool. I considered taking measurements of the tool. But I did not. Look at the new seal and notice the seal contact points, flaps. The flaps on the seal make contact with those 2 parts. If the upper and lower oil pan part has a gap then you will get and oil leak. If the 2 parts produce a smooth transition then no leak. Again I think you can do this without the tool, now that I have done it. Work relatively quickly ( 1-3 minutes) so the sealant does not dry and have plenty of access to the area while aligning them.


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