rear main seal

[engatwork]

I have determined that my rear main seal is causing my oil leak (98k miles). I have discussed the repair with the appropriate people and know what it will take to pay to have it replaced. I have pulled engines out and put them back in before but have never removed/replaced an automatic transmission wihtout removing the engine. Based on what I can tell by looking around the tranny and reviewing the appropriate manuals it looks like a pretty straight forward job. Essentially, from what I can tell, replacing the seal is the easy part - it is the R&R of the tranny that takes the time. How tough a job is this for a competent diyer? What is the hardest part of this job other than the grunt work? Would it be easier to remove the engine and leave the tranny in place? Can I get to the seal to replace it properly if I only remove the tranny?
thanks,
engatwork
'95 E320
'97 Honda CRV

[Benzmac]

The ONLY way to do this is to remove the tranny. It is really easy to get out if you have the specail tools...I have the ones needed and can pull the tranny easily.

I have NEVER pulled an engine for such a job.

You are right in the assumption that the tranny R&R is most of the labor. Also, with the tranny out, it is a good time to replace the transmission front pump seal. They all leak eventually.

[cth350]

What tools are needed besides

- a lift (or a pit)
- tranny jack
- assorted flare wrenches
- big mother crows foot to loosen lock nut on the drive shaft.
- 10mm allen key and really long extension & swivel for the starter.
- engine-specific guide for the seal.
- ready supply of cuss words when you pour fluid down your shirt.

-CTH

[engatwork]

The technical publications (the CD rom and Alldata) that I am reviewing shows a "main seal installation tool" P/N 601 589 03 43 00. In addition a couple of other items are "crows foot" P/N 126 589 00 01 and "tranny support" P/N 140 589 02 62 00. I guess that you should be able to use a trans. jack to serve the same purpose of the tranny support. I will look at that some more.
Now in reviewing the data and looking inside the bell housing I notice that I have what is called the "stretch bolt" that holds the driven plate on. I would imagine the thing to do is replace these bolts with the "internal torx bolts and I would tighten them to the specs which says 45 Nm + 90 degree tightening angle. Based on what I am reviewing it looks like the 90 degree tightening angle is making sure that you hold the torque wrench perpendicular to the socket to insure accuracy. Now a couple of more questions.
a) The CD says that as of May 1995 the stretch bolt was replaced with an Internal torx T55. Shouldn't I go back with the "upgrade" of the internal torx during reassembly?
b) Donnie is there another term for the "transmission front pump seal". I do not find that particular term referred to in the CD or Alldata.
Any other comments/thoughts are welcome

thanks,
engatwork
'95 E320
'97 Honda CRV

[Arthur Dalton]

I think 45Nm + 90 degrees means to torque to
the specified 45Nm and then give it another 1/4 turn.
Anyone ??

[stevebfl]

Your concept of angle of rotation torqueing is wrong. Naturally all torque should be applied perpendicular to the bolt shaft, but the purpose of torque to yield fasteners and application has nothing to do with this.

To understand this type of torque one must understand the concept of yield; inelastic deformation. While hard to feel in most applications (without measuring devices), I'll give a simple example. Take a coat hanger and straighten it. Now bend it at a point. First bend it only far enough so that when released it goes right back to its original shape. Now bend it further so that it doesn't go fully back. In this case yield has taken place; inelastic deformation; it won't spring back. Try this slowly and you will find that the amount of force necessary to continue deformation goes down once you have exceeded the point of elastic deformation.

The process of slip (inelastic deformation) is unique in metals and takes place through a unique process called dislocation propagation (at least it was 27 years ago when I got my B.S in Metallurgical Engineering UofF 1974). It makes metals different from everything else.

Back to the point. The bolts used in these situations are often neckdown bolts (have a thin area designed to stretch (inelastic deformation). They are designed to stretch so that all of their ability to spring back is used up (no sure of why all that is important but it is what is being used). SOOO, when you are torqueing one of these bolts the 45Nm is measured during the elastic deformation phase. The designer then knows that further turning will start to stretch the bolt and the torque necessary to do this is LESS and as such is no longer a good measurement of the amount of stretch. The angle of rotation is an exact measure because the bolt has so many threads per inch/whatever. These bolts have a minimum thickness and are often used only once (BMW and VW head bolts are two examples). Most MB applications can be verified by checking a minimum thickness although if they have a newly designed bolt I would change them all.

BTW, back to the cloths hanger. For those who have tried to cut one by bending it back and forth till failure, you will notice that the darn thing keeps changing the point which is bending. This is a good example of "work hardening". In practice the lines of dislocation start pinning the propagation centers causing the force to slip to go up. The joint work hardens and the hanger starts flexing right next to the spot where it is still soft.

[Edited by stevebfl on 12-16-2000 at 10:49 AM]

[engatwork]

Thanks for the correction ya'll. After looking at the picture again it does look like they are just showing turning it 1/4 turn or 90 degrees after reaching 45 Nm.

The print out from the CD has the following note:
If no tightening angle wrench is available, the stretch shank bolts can be tightened further to the specified angle in a single operation (this is what you are referring to I think) with a wrench socket and tommy bar. A flexi-rod torque wrench must not be used for tightening according to degrees of angle in order to avoid angle errors.
In addition, it goes on to say - The internal torx bolts installed as of May 1995 must be used only once and should be replaced after each removal and installation operation. The torque chart for the internal torx bolt does not make any reference to "stretch shank diameter".
If I decide to undertake this job I will plan on using all new internal torx bolts, tightening to 45 Nm and then 1/4 turn. If this is not right please let me know. I have done this before on a Japan built vehicle but on that one I just torqued the bolts to what the manual said.
thanks
Jim
engatwork
'95 E320
'97 Honda CRV

[engatwork]

If the rear main seal was leaking shouldn't I see some "streaks" on the rotating parts inside the bell housing? The rotating parts are clean and dry. The area at the bottom of the bell housing is accumulating oil. Is there any other place oil could be coming from that would allow it to accumulate in the lower part of the bell housing and show up dripping off of the bolt heads underneath the starter area? Have not decided to try to undertake this job myself but I have ordered the parts from PartsShop.com. Anybody ever seen oil leaking from around this area on this style engine before and if so where was it coming from?
thanks,
Jim
'95 E320
'97 Honda CRV

[engatwork]

I have a new rear main seal now. Got the transmission on the ground late yesterday and put the new seal in today. It was quite obvious that it was leaking once I got the flywheel off. There was oil everywhere against the back of the engine behind the flywheel. Late this afternoon I got the hard bolts back in the transmission. I will finish the job tomorrow.

A couple of thoughts - the techs are absolutely correct when they tell everyone to BE CAREFUL when messing with the plastic pieces on a car with milage. I won't say which one I broke but it is going to be a relatively easy fix. The seal was the easy part - removing/replacing the transmission is by far one of the hardest things I have ever done on an automobile and I think I am going to move into LBibles camp. Nothing but manual transmissions for me from now on. I have not told the wife yet .

Thanks for the help/advise everyone!
Jim
'95 E320
'97 Honda CRV

You are now the reigning RMOS King! As King, your duties are to monitor the forum for this subject and keep us on the right track when the subject comes up again! I'm really glad it turned out well. Isn't it a very good feeling when you have performed a personal best!?

[G-Man]

I do not have oil puddling in the bottom of the bell housing. I think I have traced the leak to the oil filter housing/oil cooler. It is very difficult to see up there but it appears the oil is dripping from the gasket on the front of the oil cooler. I will be ordering parts monday. I have to remove the intake manifold and most likely the starter to accomplish this. Mine looks like no picnic but still sounds better that pulling the transmission. Congratulations on your success.

[engatwork]

Finished up late this afternoon and took it for a warm up/test drive. Topped off the tranny fluid and it looks like it is good to go for awhile. I would only recommend a job of this magnitude for a hard core diy'er. Took approximately 18 hours total (spread over three days) and I had to purchase a couple hundred $ worth of tools (I am a sucker for purchasing tools). The seal was the cheap part -from PartsShop.com obviously. If anyone ever needs to borrow a rear main seal press tool or the wrench to loosen the propeller shaft clamp nut for the E320 car just let me know.
Deezel - I do not want to be the RMOS king . Too much work. I would rather be the AF (air filter) king.

Thanks for the encouragement and help everyone. Now I feel like there is nothing that I can't do to this fine automobile.

Jim
'95 E320
'97 Honda CRV

[Benzmac]

Great job! I hope that you removed the alumminum housing that holds the seal and cleaned it and resealed it too. Mercedes recommends to replace this housing at every rear main replacement although I have had better luck with resealing it.

I have seen where the housing will cause seeps...

OK, King of AF's, since you volunteered! Also, I'm like you, I'm willing to spend two hundred on tools plus my no charge labor to do a job that will cost two hundred at a shop. Keep up the good work!

[Ashman]

Aren't we always trying to find an excuse to buy new tools? hehehe

Don't let me loose in places like sears that sell tools. with a reason to spend, I'll end up buying every tool they got. LOL

Alon