300SD OM617 Valve Seal Replacement Help
 

I have read that the valve stem seals on the OM617 can be replaced without removing the head, no problem... But how? I have read it can be done by just removing the valve springs and old seals without removing the camshaft following the below method, but I don't see how this works. The camshaft is in the way. Too close to the top of the valve stem to allow sliding the protective sleeve on over the threads of the stem, placing seal, washer and socket between the camshaft and socket.

What am I not getting? Who has done this without removing the camshaft and what is the secret.

1. Put a protective sleeve on the valve stem threads (not enough room between cam and top of valve stem for this to work)

2. Oil up the seal

3. Place seal onto valve stem

4. Place washer onto seal

5. Place a socket on top of the washer (again, I don't see that there is enough room to do this)

6. Pry down on the socket with a protectively wrapped lever to slowly push the seal down onto the valve stem.

You do need to remove the Rocker Arms, the whole assembly.

Do one Cylinder at a time and the Cylinder has to be up to top dead Center so the Valves don't drop inside of the Engine.

Should be more info:
DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum
PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

The rocker arms are already off as can be seen in the pictures and there really isn't a lot of room.

I attached a PDF while you were posting.

Diesel911... I didn't find anything in either link that talks about installing the seals with or without the factory tool. Am I not searching properly?

Once the Piston is up at Top Dead Center the Valves on that Cylinder can be pushed down a bit and you can easily slide on the Sleeve, lube the Sleeve and slide on the Valve Stem Seal.
I used a Pipe Bushing with the Hex side down and got 2 fingers of each hand on each side of it and pusned down on the Seal and they easily went on.

Also your pictures do not show up on My Computer with Dial up Internet. I can only intermittantly view even the Pictures that I post.

In a previous Post I posted a picture what I used to push the Seals on. When I did mine I followed the Factory Manual and substituted the Pipe Bushing for the Factory Tool.

Also when looking at the Repair Links some People get stuck on the fact that it does not have their exact Engine or Model listed in the Links.

Putting the Valve Sem Seals on 617.952 Engine or a 616.*** Engine and your Engine have the same proceedure.

When People write a Thread they often leave out little details or don't take all of the needed pictures and you need to read several Threads to find the specific missing information.

In the pic it looks like a lot of room to Me.

It's not a lot of room to allow sliding on the protective sleeve over the threaded part of the valve stem, but I think I was just too worried about messing up the sleeve. After coating in oil I was alble to "manipulate" the sleave over the valve stem, but I did have to bend/twist/force it on there. There is plenty of room for the seals. In the end I was able to get the #1 cylinder intake and exhaust seal installed. The washer trick worked great and I was able to push the seals into place with only my hands, no prying required. Diesel 911, I like your pipe bushing "tool"... Gives you a little bit more to grip as you push the seals into place.

HUGE PROBLEM....

Good news is that I was able to replace the seals on the #1 Cylinder.

My problem now is I moved on to #2 cylinder and ran into a huge issue. I was able to get the two top nuts off but, one of the lower nuts is deformed. The inner threaded wall of the nut has somehow (probably my fault) been pushed into the grooved portion of the valve stem. Like staking a pinion nut. I can't tighten it or loosen it. I could use more force but, I have already started to round over the nut using my special open ended wrench. I don't wan't to mess up the valve stem threads and then end up having to remove the entire head to replace a damaged valve.

Possible Options:

Option #1
Use my Craftsman nut splitter to try and split the nut off the valve stem. There is enough space but, I worry this method may also damage the threads.

Option #2
Try using a very small ignition file to see if I can file away the deformed area of the nut that is deformed into the vlave stem groove and hopefully be able to back off the nut. I can see this option working but, may take a lot of time to removed enough metal so the nut is no longer "staked" on. The plus side is, if this option works, I run a very low risk of damaging the valve stem threads.

Option #3
Remove the camshaft so I have enough room to tap on a six point socket onto the nut, hold the valve spring retainer so the valve doesn't turn and using enough force to "overcome" the portion of the nut that is staked. I really would like to avoid removing the camshaft but, the FSM doesn't make it look all that difficult. I still run the risk of damaging the threads on the valve stem.

Option #4
Get pissed off about the whole situation and just pull the whole head and have it rebuilt (engine has 122,000ish miles and a smoking issue) The plus side is I would have piece of mind that the head is new, new headgasket, new intake and exhaust gaskets and rebuild the turbo (already have the kit) The down side is I really don't want to spend the time and money and the hassles of removing the entire head if only the valve stem seals are my issue.

Opinions very welcome......

At TDC, the valve stem is at its highest with the least room. No need to bend anything to get the bushing in. Just lower the piston a little to get more room.

Regarding your deformed nut. Can it be rotated to get the wrench on 2 flats that are not deformed?

I can get a wrench on the nut but, an open end wrench doesn't have enough contact points to not round off the nut. Hope that makes sense. I may be able to "tap" a box wrench over the nut that would allow enough grip without further damaging the nut. I'm just not sure how much force will be required to overcome the "staked" section of the nut that is in that valve stem groove and if the valve spring retainer portion that indexes into this groove would be enough to stop the entire valve from rotating.

I could always chase the threads on the valve stem after the nut is off to clean up the threads if need be but, then the question would be, how do I hold the valve from spining as I run the die down over the threads? Maybe a thick piece of rubber and a pair of vice grips? I definitely don't want to damage the valve stem itself.

You could camshaft and put a 6 point socked on the nut, observing all precautions w/ respect to dropping the valve, and re-tourque the cam bearings.

You could also bend an offset into a box end wrench w/ a blow torch and a vise. Remember that things stay hot well after they stop glowing.

All I can say is that I did it and that those are My Pictures that I posted and you can see the Protective sleeves on them.

I have faith that you will figure it.

Good info. I never thought about changing them. What symptoms tell you they need changing, other than cracked rubber pieces sitting on the head? In a gas engine, a bad seal will suck oil into the intake and cause blue smoke after sitting long at a stop light. In a diesel, there is almost no intake vacuum to suck oil, plus it would likely burn just like diesel, so are the valve stem seals essential?

In My case I believed that it was exhaust gasses getting past the Exhaust Valve stem Seal contributing to the Blow-by gasses.

If chainging them helped reduce Blow-by it was not enough for Me to tell.

When I did it many years ago the Miestersatz (spelling?) seal kit was about $17 with no shipping as I bought enough other stuff to get free shipping.
So it was cheap to see if the Seals were the cause of some Blow-by.

Well, I was able to get all the other valve stem seals on other than the one with the messed up nut. I'm going to try using a dremel with a small cutoff wheel to cut a split in the nut where the groove is in the valve stem. Hopefully this will be enough to allow me to twist off the nut without damaging the valve stem threads or without taking the cam off.

I'm not sure what a bad valve stem seal looks like, but all of mine looked to be in pretty good shape.

I was able to cut a "relief" slot in the adjuster nut and with very little force was able to get it off. I tried to protect everything as much as possible and when done cleaned everything up as much as I could.

Now the question is, do I need a special nut to replace this jam nut? Will any metric nut work or is this special, like hardened or something? I don't have a larger order to place to justify shipping and my nearest MB dealer is an hour away.

I would not take a chance on not using Nuts made for the Job.
The Upper large Nut has a handed tip on it and the lower one is thinner that a regular Nut.
Also on My Year and Model the Valve Rotates. So you don't want anything giving because it is too soft and then having the Valve Rotation turn the Nuts.

Where you having a symptom you are trying to fix?

On most Cars the Exhaust Valve Seal gets harder due to the Heat.

I am trying to determine and fix an issue with my car smoking.

YouTube link:

1982 Mercedes 300sd Smokey Exhaust - YouTube