Rear Crankshaft Rope Seal Replacement Without Removing Crank - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 05-14-2011, 05:35 PM

I pulled the engine (617) out of my CD to fix some oil leaks. I wanted to replace the front and rear crankshaft seals. The front was fairly easy, but I "opened up a bag of worms" on the rear. I made the mistake of trying to push the rear crankshaft seal around the journal like I used to do on Chevy V8's. Like the numbskull that I can be, I did not consult this forum first and I ruined the old rope seal. I was committed now, and had to replace the upper seal. I went on the forum (a little late) and searched for a how-to on rear seal replacement. Somewhere I read that someone thought it was possible to remove the main caps and lift the crank to get enough room to remove the old seal and replace it. That is they THOUGHT it was possible. Since I did not want to remove the head in order to remove the crank, I decided to at least try it. Well, GOOD NEWS! It is possible, and it is done!

I decided I would take photos and do a how-to for those that would like to replace their rear seal without removing the crank.

Here is the process:
Remove the upper oil pan so you can suspend the engine with chain through the engine damper holes so the flywheel and adapter plate can be removed.

With your engine on an engine stand (bolted to the adapter plate holes), remove the valve cover, cam chain guide, and cam gear.

Next, remove the oil pump and main caps.

You will need to remove the oil jet for the cyl that is on the bottom of it's stroke (to allow the piston to go further down the cyl).

Raise the crank up evenly (about 3/4") and support it in any way that will hold it. I used a piece of wood in front, and a screwdriver in the rear. Remove the old seal. Clean out the seal groove with brake cleaner.

Now would be a good time to replace the front seal as well, providing the pulleys and harmonic balancer are removed before removing main rod caps.

The old and new seal.

Install the new seal so about 1/4 inch is sticking out above the deck on one side. Use a 1/4 drive socket extension to force the seal in the groove, rolling it on the seal surface. There is a pin in the very center, so more pressure will be required there. Put assembly lube on all main journals, and the seal. Lower crank back into the upper bearings.

Install the main caps and torque to proper specs (66 ft. lbs.). Install the oil pump. Trim the seal leaving it 1 mm proud of the deck on both sides. Be careful not to score the surface of the crank. Install the other half of the seal in the upper pan and install the pan using the proper metal to metal sealant (described in another thread).

I will let you know how it worked when I get the engine in the car.

Stretch · #2 05-15-2011, 06:12 AM

Interesting fix - thanks for sharing.

I see you used the crank and torquing it in place to position the seal in the groove whereas the FSM says to carefully roll into the groove...

...as I said in another thread (Rear main seal) I have been told by an engine builder here in the Netherlands that if this seal isn't seated correctly it can cause localised heating (due to friction) that can knacker the nearest main bearing.

Now I don't know for sure if that is gospel - but it is what I was told.

I would have re-lifted the crank after torquing to make sure it had seated nicely.

Let us know how it goes.

ROLLGUY · #3 07-27-2011, 01:37 AM

I finished the job a while back, and NO LEAKS!!! It was well worth the effort and expense to do the job right.

leathermang · #4 07-27-2011, 02:50 AM

Quote:

Originally Posted by Army

....I see you used the crank and torquing it in place to position the seal in the groove whereas the FSM says to carefully roll into the groove...

Army, I thought when he said this: "Use a 1/4 drive socket extension to force the seal in the groove, rolling it on the seal surface. " that he was doing what you refer to and the FSM says to do.........???

Stretch · #5 07-27-2011, 04:35 AM

Quote:

Originally Posted by leathermang

Army, I thought when he said this: "Use a 1/4 drive socket extension to force the seal in the groove, rolling it on the seal surface. " that he was doing what you refer to and the FSM says to do.........???

Pushing my rope seal in place took a lot of effort - the desire to rub is immense! Roll - don't rub!

Hats off to ROLLGUY for managing this with a 1/4" drive socket extension.

leathermang · #6 07-27-2011, 10:16 AM

Yes, clearly he did not have the room shown in the FSM when they did not have the crank so close to the seal.... but he sure had to do a lot of heavy lifting to manage this ...since he said ' rolling' I am hopeful everything went in perfectly... or maybe he is stronger than you and I are ? LOL

winmutt · #7 07-27-2011, 11:30 AM

Rumor has it the rear rope seal can be replaced with engine in the car. By rumor I read it years back in one thread. Never heard or seen any other ref to that.

Stretch · #8 07-27-2011, 11:56 AM

Quote:

Originally Posted by leathermang

Yes, clearly he did not have the room shown in the FSM when they did not have the crank so close to the seal.... but he sure had to do a lot of heavy lifting to manage this ...since he said ' rolling' I am hopeful everything went in perfectly... or maybe he is stronger than you and I are ? LOL

Uh oh - are we back to boasting about our ballet dancing around garages with engine blocks under each wing again? Mine was an OM617 and yours was an old XK120 Jag wasn't it?

Stretch · #9 07-27-2011, 12:00 PM

Quote:

Originally Posted by winmutt

Rumor has it the rear rope seal can be replaced with engine in the car. By rumor I read it years back in one thread. Never heard or seen any other ref to that.

You could probably change the seal in the upper oil pan with the engine in place (more or less - perhaps a bit of lifting so the oil pan clears the cross member and the engine shocks). But if it was the whole seal - well wow I'd like to see that!

I bet they did something really clever like removing the upper oil pan and then spinning the engine up to 30,000 RPM - watch the old seal squeal and jump out whilst carefully feeding in the new one - whilst keeping all their fingers... it must have been magic...

leathermang · #10 07-27-2011, 12:22 PM

Quote:

Originally Posted by Army

Uh oh - are we back to boasting about our ballet dancing around garages with engine blocks under each wing again? Mine was an OM617 and yours was an old XK120 Jag wasn't it?

That was clearly placed in a ' stupid things I did as a youth' thread...not something I am proud of...

leathermang · #11 07-27-2011, 12:24 PM

Quote:

Originally Posted by winmutt

Rumor has it the rear rope seal can be replaced with engine in the car. By rumor I read it years back in one thread. Never heard or seen any other ref to that.

Those rumors were dispelled by pictures posted several times of the PIN in the top...which keeps a new one from being ' slid' in....which on some American cars... was one of the neatest tricks I ever participated in... much like attaching our new chains to the old ones and rolling them in...

ROLLGUY · #12 07-27-2011, 10:56 PM

Quote:

Originally Posted by winmutt

Rumor has it the rear rope seal can be replaced with engine in the car. By rumor I read it years back in one thread. Never heard or seen any other ref to that.

The rumor is false (partly). The only way to replace the UPPER half of the rope seal is to remove the engine from the car. Yes, the upper pan is removable with the engine in the car, but a real pain in the rear. IMO the entire rope seal needs to be replaced if a leak is present.

ROLLGUY · #13 07-27-2011, 11:01 PM

Quote:

Originally Posted by Army

Pushing my rope seal in place took a lot of effort - the desire to rub is immense! Roll - don't rub!

Hats off to ROLLGUY for managing this with a 1/4" drive socket extension.

The hardest part is forcing the seal into the pin. The rest of the seal rolls in quite easy with a thin round object (1/4" drive extension). You must also use assembly lube on the seal (making sure not to get any lube on the ends of the seal where the two halves join).

dkveuro · #14 07-27-2011, 11:07 PM

Here's something interesting but not MBZ.......retro install !

http://www.justanswer.com/classic-cars/4hwai-cadillac-deville-1965-deville-rear-main-leak.html

Why not have the "pin" in the cap instead of the block?

ROLLGUY · #15 07-28-2011, 12:07 AM

Quote:

Originally Posted by dkveuro

Here's something interesting but not MBZ.......retro install !

http://www.justanswer.com/classic-cars/4hwai-cadillac-deville-1965-deville-rear-main-leak.html

Why not have the "pin" in the cap instead of the block?

Both parts of the seal in an MB Diesel are not part of the bearing cap. If just replacing the lower seal, the main bearing cap does not need to be removed.

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