Relpacing front radial seal - PeachParts Mercedes-Benz Forum

ATLD · #1 06-17-2002, 01:29 AM

I have just decided that it's time to give my driveway a brake from small oil drips, so I guess it's time to do the Front Main Radial seal. It leaks only about a liter/6mo. but it amazingly looks like a lot more spread out on my driveway. Nothing else leaks and I'm now certain that It's the radial seal thanks to dyes and UV lights.

Any recomendations. I know that the MB cd and Haynes state that I need a plethora of special tools. Which ones do I need to buy, and which ones can I do without.

Anyone's shared experiece in doing this job would be grately appreciated as the procedures I have are somewhat nebulous.

TIA
ATLD

tcane · #2 06-17-2002, 01:42 PM

The Haynes manual has a good R&R procedure with the minimum number of special tools needed (I've done this several times). I will add this because Haynes does cover it but can be overlooked - the front crank seal inner lip rides on a spacer ring that is a separate part ffrom the crank (called a crankshaft spacer ring). Inspect this ring for grooves, if it has grooves/imperfections it needs to be replaced because it will wear on the new seal's lip wearing it out faster and the leak will return.

Good Luck!
Tom

ATLD · #3 06-17-2002, 09:51 PM

Yeah, I have the Haynes and MB cd. Luckily, when I ordered the parts last night I saw the spacer listed next to the seal. I bought both and a few other things.

Are there any tricks or is it just as Haynes says? Now I just need a torque wrench that can produce and read 250ft/lbs in addition to a balancer puller!

Adam
ATLD

psfred · #4 06-17-2002, 10:29 PM

Getting the spacer out if it is stuck can be a pain -- you may want to find a very narrow jawed gear puller. If it isn't stuck, though, the repair is easy.

My brother left his out (it was missing on the short block he bought to replace the blown crank and we didn't dissasemble the old engine until the new one was rebuilt and installed -- plus he gets in a hurry). Installation was pretty simple -- look up Larry Bible's posts on getting the balancer back on without getting the alignment pins out of place. It is fairly easy to damage the balancer or crankshaft.

Otherwise, it is just pull the balancer, pull the old seal, tap the new one in, and replace balancer.

We have made any number of "pullers" with 1/4" steel plate with a nut welded on it and appropriately spaced holes drilled. Not as nice as a proper tool, but much easier to come by on short notice.

Peter

tcane · #5 06-17-2002, 11:32 PM

ATLD:

I was busy and overlooked info on installing the balancer plate (M-B term for harmonic balancer). You need to look up an old post by me in response to a question by Larry Bible on the correct way to install the balancer plate without damaging either the balancer plate the crankshaft or both - I wrote to Larry the best method to install the balancer plate. You can look up old posts about folks ruining the balancer plate/crank from incorrectly installing it. It is not an easy process, but not having oil pour out the front of the crank is really great.

Auto Zone loans tools and other auto parts stores also - call around to find one in your area loaning tools. You'll probably find a tool to pull the balancer plate (but call it a harmonic balancer or the parts guy will look at you like you're from another planet) and the torque wrench. Usually you need to leave a deposit equal to the cost of the tool - your credit card will cover this. If no parts store in your area loans tools, then rental places rent tools.

Good Luck!
Tom

ATLD · #6 06-18-2002, 11:53 PM

Thanks for the advice. I will look up your posts; but I already bought a snap on 250ft/lb torque wrench and the harmonic balancer puller. I also bought a craftsman 2 3/16 socket that will help me install the seal; as per Haynes suggestion.

Does anyone know how to remove the seal spacer?
Haynes glosses right over it. I bet it's a press fit thing. I hate those! *lol*!

TIA

ATLD

psfred · #7 06-19-2002, 10:22 PM

ALTD

When new and clean, it just slides on. When old and dirty, it is often stuck. You will have to get hold of it through the seal opening with something like a gear puller with very thin arms. It won't be very stuck, but enough to be a real pain. If you used good oil, it might just slip off with a hooked scribe, but I'd be planning to remove the radiator if it doesn't.

Peter

ATLD · #8 06-20-2002, 02:17 AM

Well, I hope my good friend "PB Blaster" can help me out on that. It's freed up the most amazing things. Really is worth its weight in gold. Otherwise, I thought I would have to remove the radiator anyway? The harmonic balancer puller I bought is not at all small, but it should do the job; anyway, I haven't yet looked at the under-hood clearances.

Now, my only concern is about reinstalling the balancer. From what I've read, it's going to be a pain to get it "just" right. Now, other than the obvious balance problems that happen when the balancer isn't installed right, can someone tell me what happens that's so "catastrophic" when the balancer is mis-installed and why? I however plan on taking my time to get it right.

Thanks again oh you wizards of mechanics...

ATLD
Adam

psfred · #9 06-20-2002, 10:11 PM

Adam:

The real problem with installing the balancer is that it is located on two hardened steel pins -- the fit into recesses between the balancer and crank. Neither crank nor balancer is particularly hard as steel goes, and if you put the pins in part way and try to pull the balancer down with the bolt, the pins dig in and distort the crank and balancer. The burrs thusly pulled up make it very difficult to remove the balancer again, and can prevent it getting completely installed.

What you need to do is offset the holes a bit so that pulling the balancer back into position with the bolt causes them to end up in correct position to gently tap the pins into place. It may take a couple of trys to get the offset correct. This is vastly preferable to having the pins dig into the crank and balancer and scoring them.

I don't know how much room there is on a 123 chassis between the crank and rad -- on the 115 there isn't much!

Peter

ATLD · #10 06-21-2002, 12:52 PM

Good to know. Thanks eveyone and wish me luck. I'm going to replace my timing chain, front seal, oil filter seal, stearing dampener, front control arm basll jnoints, and a few other small things this weekend, after I get my BMW up to par again.

Thanks again for all the good and educated advice. I couldn't do it without you guys!

atld

Adam