HELP!!! M104 Upper Timing Seal - PeachParts Mercedes-Benz Forum

gmercoleza · #1 11-03-2005, 09:59 PM

I have done a search and am surprise I don't see too much info on this. The info that is there is not specific to what I am experiencing. Is it just me???

I have plenty of experience doing the u-seal on the M103. But I have a M104 apart for the same job and am having great difficulty reinstalling the cover while keeping the seal from sliding out of the groove. It seems that the problem is the chain guide pin which forces the cover to be lower than I'd like it to be. The result is that it scrapes the u-seal off every time. I am getting very frustrated.

I know I could spend 8 more hours trying to finesse this seal into place. I'm worried that the black sealant will dry if I let it sit overnight.

Can the experts please share any tips to finish this job? I am so so close...

Do I need to remove that pin? It doesn't look like that would be a good idea, as the chain guide would probably give me some real problems reinstalling.

HELP!!!

gmercoleza · #2 11-03-2005, 11:24 PM

OK, I just figured out how to remove the pin from another thread (didn't see that the first time somehow). So the pin is out now - I'll finish the job tomorrow because it's late. Will I have trouble realigning it once the cover has been reinstalled? Also, I assume I just lightly tap it in flush with a hammer and then finish the rest of the insertion using the threaded allen cap?

One other thing - what about the camshaft position sensor? I'm assuming it just goes back in any which way? The reason I ask is that it doesn't appear to be keyed or anything, just sort of free-spins with slight "magnetic" resistance?

Any additional tips or tricks that can get me through this job would be greatly appreciated!

TIA!

gmercoleza · #3 11-04-2005, 12:24 PM

Bump - anyone? I'm particularly worried about the sensor which is not keyed...

bwheitman · #4 11-05-2005, 10:07 AM

The upper timing seal as you are finding is very tricky on the 104. I don't know about the pin you are talking about, I would think it is an alignment pin. I will tell you how I did mine, I hope it helps. I would think the alignment pin needs to be intact in order to ensure the cover is set properly in place.

When you take it apart, maintain cleanliness. This is important, do not get any dirt in the engine, and change your oil after you have completed repair and verified there are no leaks.

When dis-assembled, clean everything. especially the back of the cover where it meets the head, there is no gasket here. I used a slight film (very slight) of silicone before re-assembly.

There is a groove in the top of the bottom protion of the timing cover. This is where the u-seal sits, this groove has to be very clean and it will hold the seal in place while you push the cover in.

After everything is clean, put the u-seal in the groove, I dabbed a small amount of silicone along the bottom and the ends of the seal, pop it into the groove. Then take the cover, put a small film of silicone on the edges where it meets the head and work it in. The bottom of the seal is grooved, but the top of the u-seal is not, that is how it stays in place, work the cover slowly into place. Once the cover meets the head, get a flashlight and check the seal. Sometimes you have to move the cover back out just a little bit, and then back in to ensure the seal is seated right. But you can see it, provided the area is clean, remember it has to be very clean. The seal is green so easy to see.

The magnetic variable CAM controller on the intake side requires no adjustments or attention for this procedure. Just make sure it is clean, the variable portion of the cam rides inside the magnetic adjuster.

When using the silicone use very little. You don't want any breaking off and getting into the engine as it can cause clogging of the oil galleries. Just a slight film that is all. I used a little more on the ends of the u-seal where it is butted up against the head, that is where they all leak, four parts of the engine come together there, so with all the hot and cold, it is a no wonder they leak. After you replace it and do it right, you shoud be good for another 7-10 years.

With every Mercedes there is a procedure for repair, just take your time and look at it, you will figure it out, the cars are meant to be worked on.

Good luck !
Brian

bwheitman · #5 11-05-2005, 10:10 AM

Hey,
I see you are in Collin County, I am in Plano, if you need me to swing by and help you with this let me know.
Brian

gmercoleza · #6 11-05-2005, 10:33 AM

Hey, thanks for the tips. The car is up and running already. I had never done this repair on a M104 and didn't realize the chain guide pin should be removed while the timing cover is still installed. What I did was thread a bolt into it (didn't know it was threaded, learned that here on the forum) and use small combo wrenches as spacers, then gradually tightened the bolt to pull the pin. It came out with a "pop" sound. Once the pin was removed, everything was very easy, just like on the M103. Installation of the pin was rather easy, too, and was assisted by the hex plug that covers the access hole.

I'm familiar with procedure for properly prepping surfaces and adding just enough sealant that it doesn't ooze out into the engine (I used the MBZ black sealant). I also installed the U-seal dry as it should be - the previous butcher somehow thought using black sealant all over the gasket was a good idea, and I had to clean out the U-channel. I just put a dab of black sealant on each end of the U-seal and put a light coat of oil on the top to assist in assembly. All went fine from there on out.

But thanks for pointing out that information as I'm sure plenty of members here can benefit from it.

Oh, and thanks for the offer of help too. I may take you up on it someday!

Regards

bwheitman · #7 11-05-2005, 10:36 AM

Great Job! I am happy to hear you got it figured out.
Happy Benzing!
Brian