M103 Valve Seal replacement
 

My 1992 300te 4matic burns a quart every 400 miles. It's been changing itself... However, it's time to replace the valve seals.

I do not as of yet have a manual, but following hints and suggestions from this forum, I have truely saved thousands. Thanks to all!

Valve seals - dumb question - am I going to have to pull the cam? Ok, it is a single overhead cam, I just didn't know if the cam itself obstructs access to the valves. A friend said to rig the compression tester to pressurize the cylinder, that's simple enough.

Other than replacing the valve cover gasket, is there anything else that should be done while I'm in there (glass beading and re-spraying the valve cover).

Thanks!

Jerseyjeff

Below is a repost of some questions I asked on a 2005 thread just the other day. Since this is a new thread I thought I'd add these questions.

I plan on doing this job on my 92 300 TE with 134K miles. On a trip this past weekend I used about 2 1/2 quart of oil in 1300 miles.

Questions:
1- Is the KD 2078 which is available at Sear what people are using? It's a universal spring compressor.

2- Is a magnetic keeper tool, available from Mercedes quite inexpensively, helpful in removing the valve keepers?

3- If the piston is positioned at TDC of the cylinder you are working on then there is no possibility of the vavle falling in the cylinder. Is that correct?

4- There is or was a special pliers to remove the old valve seal. Is this tool necessary?

5- Do people use a small pencil size magnet to pull the valve up? Or for any other purpose?

I plan on doing this job on my 300ce with 134k miles sometime in the late spring, I hope.

Kitchen remodeling keeping me too busy now.

I am very interested in the answers to a lot of those questions as well.

Over time, I've read just about every post written that dealt with M103 valve stem seal replacement.

Yes - the KD tool will work, but some will tell you it's easier to use the special set of MB tools that were around $150-$200 last time I looked. Do you REALLY need this special set for what might be a one time repair? Some have done it w/o the special set.

Anyway - here's a pointer to just about ever thread that deals with this task. In the end, you'll learn that there are all kinds of opinions about what tool to release spring pressure with and strategies in pressurizing the cylinder.

http://www.peachparts.com/shopforum/search.php?searchid=607012

I've just done this job. Cam is not removed. It is recommended to only remove one rocker tower at a time so as not to stress the cam. Make sure you plug the drain holes in the head, you don't want to lose anything into there. Make sure you keep the rocker buttons?? matched to the lifters/rockers, you don't want to get them mixed up. The standard spring compressor with the thumbwheel worked fine for me. Use tweezers or dental picks to remove the keepers. Lock the crank with a ratchet against the pulleys to make sure it doesn't spin when you apply air pressure. Use an appropriate torque wrench for the tower bolts ie. not a 100lbs unit. You don't want to strip them.

Two thumbs up for the Mercedes hood design!

Jorg

M103 valve seal replacement - thanks!
 

Looks like a bunch of us are all planning to do this at the same time. So glad the head does not need to be replaced.

Sounds straightforward enough - was this a few hour job? Any risk in glass beading valve cover and repainting?

Thanks!

Jerseyjeff
170k 300te4matic (4matic on test mode) - this car is a tank

It took me about 3 hours, but it's my hobby not my job. I take my time, drink coffee, admire the parts, etc.

I soaked my cover in hot carb cleaner to take most of it off and then bead blasted. There will be imperfections in the casting but in my case they where near the #6 cyl. so I ended up just clearing the cover with a matt clear. The raw magnesium looks like business.

Jorg

I've got everything I need as far as tools, or at least I think I do.

Here's what I've done so far.
1-removed rocker arm bracket and ball sockets came right out.
2-Have cylinder pressurized to 5 bar per workshop manual.
3-compressed spring with KD tool.
4-tapped valve spring plates with a very small brass hammer to try to get valve collet halfs to detach. No luck with that So I need to determine what to do next.

I wonder if I'm not hitting them hard enough or if I'm not depressing the valve spring enough.

How many coils on the spring should the compresser have between the top and bottom part of the compressor? What might I be doing wrong?

Edited:
I think I did not have the cam positioned properly for cylinder #1.

With the cam lobe for the exhaust valve pointing straight down, I believe that is TDC for cylinder #1, the cylinder pressurized when I introduced 5 bar pressure. The ratchet I used to turn the cranked moved slightly and lodged against the pulley belts holding it in place. I believe this is correct.

I’ll depress the valve springs tomorrow and set if the valves move upwards so I can remove the collet halfs and install the new seals.

Does that sound like the way to proceed?

Smack the valves with your hammer before you compress the spring. The sound will change when you've got it right. Then compress the spring and the keepers will come right out.

I've done two exhaust and two intake seals. I don't want to speak to soon but has been real easy. I hope those don't turn out to be famous last words.

What I was doing wrong.
I was tapping the valve spring plates with a tiny brass hammer, like the little ones gunsmiths use. Well I tapped with a larger brass hammer, i.e., the one I got at Harbor Freight. I was just not tapping hard enough.

TDC markings are on the harmonic balancer. There are 3 of them.

Jorg

Car starts and runs fine, so it seems I did the valve stem seals sucessfully.

Now on to the next project.

Probably not. But don't paint the inside of the cover or have the inside powdercoated or anything like that.

That black paint was coming off of mine badly so I just pressure washed the valve cover and got nearly all the old paint off. Doesn't look perfect but a huge improvement over the way it looked before.

I hope it was the valve stem seals .... I thought the 91 300e needed them and then I replaced the front cover seal and a leaking oil level sending unit and at 240K is uses oil, but not like before. I am typically getting 2,200 to 2,800 per quart.

Haasman

While I read many posts about folks replacing their valve stem seals, I haven't seen anyone say if the replacement returned their oil consumption to a normal level?

Thanks