Valve Stem Seal Question - PeachParts Mercedes-Benz Forum

nhdoc · #1 07-18-2008, 08:25 AM

I am in the process of replacing the seals on my '74 240D. The old ones are a metal-jacketed design while the new ones are all rubber. Does anyone know when they stopped using the old ones? Would it mean these were original from '74? They are a bear to get out. The new ones, by comparison, slip down and seem to pop right in. I hope I am pushing them down far enough is all.

I ordered the drift for installing them but apparently got the wrong one as it is too small. I'm just pressing them down carefully using the end of a box wrench.

vstech · #2 07-18-2008, 08:47 AM

no idea on the seals, it would not surprise me to find they were original...
as long as the seals are seating all the way down you should be good to go. can you see the guide bosses well enough to verify they are seating down all the way?

jt20 · #3 07-18-2008, 09:31 AM

my '81 240d had the hard rubber / plastic seals all the way around. Also a struggle to get off - even with the cam removed.

don't know the year that changed.

where did you get the pressing mandrel from - cost?

1983/300CD · #4 07-18-2008, 04:56 PM

Quote:

Originally Posted by jt20

my '81 240d had the hard rubber / plastic seals all the way around. Also a struggle to get off - even with the cam removed.

don't know the year that changed.

where did you get the pressing mandrel from - cost?

Now, that is one thing that ************** did a really good job on. Since it is made from a box wrench, I found it to be a great help with the nuts on the last valve. That might not be an issue on the four cylinder, though.

winmutt · #5 07-18-2008, 10:32 AM

How long does it take to do this? I need to do this on my recently acquired om617. Its smokes alot of oil on startup.

nhdoc · #6 07-18-2008, 04:51 PM

It takes a few hours...I have not worked on it since yesterday and I got 4 of 8 done. On the 4 cylinder you can do 2 cylinders at a time (when both are at TDC). It got to be too hot to work on it any more yesterday. Tomorrow I will finish up in the morning before it gets too hot and report back on the results.

I am also replacing the springs since they only cost $4 a piece and you have to remove them anyway. Cost of springs and seals is around $60. Hoping it will help reduce my engine's appetite for oil.

I ordered the tool (a sir tools copy of the M-B tool) from Pelican Parts but they make a 9mm and 11mm and the PN for the 9mm is what the MB manual says is correct, but that one does not fit over my valves so I must need the 11mm one I guess. The tool costs around $30 and is also available from samstag.

vstech · #7 07-18-2008, 04:59 PM

when I pulled all the parts off my cracked TD head, I had GREAT difficulty getting the seals off. and I had the head OUT OF THE CAR!
found the best method to get the seals out was to put a 14mm open end under the seals, and whack them with my fist. sent the old ones flying, but it got the job done!

nhdoc · #8 07-19-2008, 11:05 AM

I wrapped up this morning. I found it useful to use a 17mm crowsfoot on a 2' extension to pry out the old seals and an 11mm crowsfoot on the same extension to seat the new ones. removal with the crowsfoot went better than trying to yank them out with a pair of pliers which is how the manual says to do it.

It took me about 5 hours to do this job including setting the valve clearances. I would say an experienced tech should be able to do it in about 3 hours but I would not think it could easily be done in much less...of course some claim to be able to adjust valves in 20 minutes too but I find that hard to believe.

First start was still kind of smoky but I am hoping that was just residual oil burning off and maybe the oil I used to lube the new seals when I installed them. Otherwise it ran fine...time will now tell if it makes any difference in my oil consumption problem. I am not terribly optimistic but still felt it was good to exhaust this possibility before concluding that it was something more sinister lurking in the bottom of the motor.

pizzachef · #9 07-19-2008, 08:06 PM

If you wouldn't mind, I'd be interested in hearing an update to this is a few weeks. My 240D smokes nicely on startup too but clears up after a few minutes.
I haven't had the valve cover off mine yet, but I assume its similar to the 617 engines...do you have to undo the timing chain to get the camshaft off? Any other technical glitches someone should be aware of before trying this?
Thanks for the info.

nhdoc · #10 07-19-2008, 08:53 PM

Quote:

Originally Posted by pizzachef

If you wouldn't mind, I'd be interested in hearing an update to this is a few weeks. My 240D smokes nicely on startup too but clears up after a few minutes.
I haven't had the valve cover off mine yet, but I assume its similar to the 617 engines...do you have to undo the timing chain to get the camshaft off? Any other technical glitches someone should be aware of before trying this?
Thanks for the info.

You don't have to remove the camshaft to change the seals, only the rocker arm towers, then the caps and locknuts, spring retainer and spring.

Lexxani · #11 07-19-2008, 09:00 PM

im in the process of doing my heads right now on the M117 (same principles apply) and I have the hardened plastic type, I found putting a medium flathead under the seal and pressing it up to work fine and efficiently, for all 16 guide seals...no special tools required. . .

I have my cam off so there is no need to use a special tool to get them bac on, its just plug and play. . .