Engine rear oil seal

[keitpago]

Hi Out there ..Would anyone be able to tell me how you fit a rear rope oil seal on a 230 pag only i just about to take the engine out again due to the fact i put in in how the book says and its done 200 miles and its leaking which means engine stripe down again crank out after a total rebuild, The book was a Haynes i need to know the right way this time I cant keep doing it all my life im exhausted.
Keith

[George Des]

As I understand it, the biggest cause of the leakage from this seal is improper cutting of the two ends. The two cut ends are supposed to be offset from the seam between the block and the cast oil pan housing so the seam between the two pieces of the seal do not line with the housing/block seam.

George

[ja17]

*this post has been updated/corrected from the original

Hello Keith,

The original rope seals were designed to extend above each mating surface *this specification can vary depending on the manufacturer and type of material, (the M130 BBB gives a dimension of 0.6mm) at the oil pan and the same at the block. However the newest rope seals are improved and tougher than the originals ( very tough to cut you will notice)l. The manufacturer of the improved material seal now suggests a 0.7mm above each mating surface). Look for a manufacturer's note with the new sea.l

Installation is not difficult but more complex than you would think. Certain procedures should be followed.  Two special tools make the job simpler but are not required. The first special tool is a round anvil (die)  like tool which is the same diameter as the crankshaft seal surface. It is used after the seal is in place. Striking the anvil with the hammer against the seal, will seat the seal deeply on the pin in the groove and will also pre-form the seal to the crankshaft  diameter. When the rope seal is seated correctly it can be cut to the prescribed dimension. The second special tool is basically a thick "feeler gauge" which has a square hole in one end which is slipped over the rope seal. A razor blade can then be used to slice the seal cleanly to the correct dimension.

Common mistakes are:  cutting the seal before it is properly seated, cutting the seal too short or too long, not seating the seal correctly, and  not sealing the ends of the seal.

You can improvise. Some techs carefully use the wooden handle of a hammer to press and roll the seal into the groove. You must be sure to deeply seat the seal on the pin in the groove. Be careful not to overdue the process and  making the seal completely flush.

I like to use Permatex #2 on my oil pan to block mating surface. Use a little sealer between the ends of the rope seal just for insurance. I also like to put a little gasket shellac in the groove before I install the rope seal. Lastly I coat the exposed rubbing surface of the seal with some graphite engine assembly lube!

*photo taken by Alfred Esser

Hope this helps,
Joe Alexander
Blacklick, Ohio

[Ron]

Thanks Joe, I'm in the process of removing my engine to do this one job.  The PO had "rebuilt" the engine, but after 1,000 miles, and puddles of oil after each use, I've decided the only cure is to replace that seal.  I was hoping for just removal of the pan, and cut that side of the seal a bit long.  But you're essentially saying I need to remove the crank too, and replace all of it.  Ron

PS I've had this car for several years and only driven a bit over 1,000 miles because of the mess it creates.  It also has water in the oil, so the head coming off to, and I'll see if I can figure out what is happening there.

[ja17]

Hello Ron,

It is usually not worth removing the crankshaft to do both sides. It is so much extra work. However, you may wish to remove just the rear main cap to make sure that that main bearing is OK.  
Also, I added a picture to my previous post, that Alfred took when we were re-building his engine. You may want to look at it.

[Ron]

Thanks Joe, I looked but the picture is really coarse in detail.  Am I doing something wrong here, or could you repost?  Or send it via my email with higher bandwidth? 

Thanks so much for your help, now and in the past. 

I've retired now, and am finally getting back to the car to get some enjoyment out of it.  First I had to clean the mice out of the trunk.  They were in the car cover on the floor next to the car, and I picked up the cover and threw it into the trunk.  They ate the car cover for a few days, but there was no water.  They died in there.  What a smell and mess, but at least they did not make it to the cabin. 

Ron

[66andBlue]

....  I looked but the picture is really coarse in detail.  ....

Ron,
it looks like the "thumb nail" pix got uploaded.  Here is the full size picture.
I'll try to find the individual ones and mail them to you if this one is not sufficient.

[Ron]

Hey Joe, this new photo works fine.  I finally see how to trim that seal, with the feeler gauge.  When I get the pan off, I see what the problem is, I hope, and let you know.  I'm assuming that if the old type seal was used in the rebuild, 3 years ago, I'll have to use a like seal half if I'm only pulling the pan.  If I pull the crank too, then I can use the totally new seal.  I feel certain the PO did not trim the seal correctly - he probably trimmed it flush with the surface.  Ron

[Benz Dr.]

I use about .50 mm or .020'' to trim the seal. I think a full millimeter would be too much. You can tell  if the seal is too tight if the crank won't spin freely. You can also have a high spot on the seal which will also make the crank bind. The completely assembled unit should be able to be moved by hand or something is wrong.

If I were to only replace the seal on the pan I would look at what the ends of the seal look like in the block. If the ends of the seal are flush with the bottom of the block, I would try .040'' on each end of the oil pan side of the seal. If the seal has been pushed into the block somewhat, you may have to use more than .040'' to make it work. Since you pretty much have to pull the engine to get the oil pan off, you would be best advised to redo the rear seal on both sides by removing the crank. You can leave the pistons in the block if you are careful replacing the rod bearings in the connecting rods.

 Cut and fitted properly, the rear main seal really won't leak, or at least very little.

[ja17]

Hello Dan and Alfred,

Thanks for the input. There seems to be a lot of variation on the specification for the dimension that the rope seal extends out of the block. There is a good reason for this since the actual materials that the rope seal is made of has changed over the years. As new and improved materials have been developed, manufacturers have adopted them for older applications.  As Alfred has pointed out, the BBB for the M130 engine specifies 0.6mm.

It seems that the new gasket sets are being supplied with an improved Aramide rope seal. The recomended spec from the manufacturer now
 0.7 mm . 

I have attached information from "Victor Reinz"  (one of the OEMs for MB) to  this post which gives the 0.7mm spec for their new version Aramide rope seal.  Aramide is one of the modern space age fibers used for very tough service like racing tire belts and space suites. Also in the post is a picture of the installation die and the cut off procedure. I will modify my previous post to reflect the information here.

[wbain]

It would be nice to have a modern rubber lip seal for this. I know they are available for various American engines to replace the rope seal.

[Benz Dr.]

The rope seal comes in one piece and it's longer than you need, meaning there will be some left over when you are done. The same seal is used for several diffrent engine types and some crank journals are larger than others so the seal may be just about the right size for a 190SL but it will be somewhat longer on a 127 - 130 enine.

I place the seal in the block with about 10 mm sticking out of the block on each side. Then I use a wooden hammer handle to press it into place. I use another hammer to tap against the handle resting against the seal until the seal is at the bottom of the groove. Once you have the seal squarely into the machined groove you can cut the ends off. I made a small tool to place around the seal so I can maintain the correct distance from the parting surface of the block.

[menesesjesse]

This is a great thread. I had a few questions for the experts. Im in the process of doing this job on a 250SL and my questions are about 2 things. The 250 Im working on runs beautifully but leaks like a faucet. I want to change the rear seal and it would seem proper to do both sides.
Does the block side rope seal fail often? If so and I remove the crank I would imagine when I replace the rope on the block side it should be cut slightly shorter to accomodate the extra length on the pan side.? If this is correct should it be cut short .7mm?

Would you recommend I just do only the pan side because it is usually the big offender in rear main oil leaks?

Since the engine runs so well great oil pressure, and there are no knocks would it be better to just maintain the same bearings since there will be no rebuild. I plan on replacing all the gaskets along with the timing chain, tensionor.

Thank you for the assistance
regards,
Jesse 

[ja17]

Hello Jesse, 

Yes we hate to see you disturb anything which is doing so well. However as you can imagine the oil pan section of the rope seal sees more wear. Gravity and the weight of the heavy crankshaft, as you can imagine, tend to wear the rope seal more on the pan half over time. Both halves are normally cut oversize. . I would spot check the third main bearing (bottom half) and the rear main bearing half just to good measure. All bearing must be kept in their exact places and must be kept clean.

[Benz Dr.]

The idea is to cut the seal equaly on each side - block or oil pan. If you remove the crank but re-use the bearings it's critical that you keep everything in order. The bearings not only wear to the crank journals they slowly conform to the bearing caps so everything has to go back together the same way it came apart.

If you find that the bearings are all scored you might be advised to pull the engine apart and have the crank checked out - I would do that anyway. If you need new bearings you will have to check the big end of the connnecting rods. Placing new bearings in out of round rods will be a sure failure.
I would also replace the crank gear while I had it all apart. If you have a standard trans get a new pilot bearing at the back of he crank.

[menesesjesse]

Thanks for the info. I will check the bearings for good measure JA. I think I will go with replacing just the lower half if all looks good. The motor has many more good miles on it. Pulling the motor is just a day job so if things go wrong 400 spent on seals and gaskets is better than potentially 5k in rebuilding cost. So permetex 2 is the consensus for sealing the pan and seal ends.
Last question here. If I leave the pistons in and just change the lower rope I want to prevent binding. Should I just measure the torque required to turn the crank prior to disassembly and match that with the new seal in place?  Thanks for all the advice.
Jesse

[ja17]

Hello Jesse,

Just follow the procedure, you should be fine.