Valve stem seal job almost done! - PeachParts Mercedes-Benz Forum

rgnprof · #1 06-07-2004, 10:03 PM

Spent today replacing the valve stem seals on my '72 250 and it went suprisingly well - knock on wood! Took me about 6-8 hours to get the seals replaced and rocker arms back on.

Just looking for some verification, or validation (whatever) before I adjust the valves and put it all back together.

None of the valve moved in the guides - noticed no wiggle room at all, so I guess that's good?

The seals on the exhaust side were different - the old ones are teflon with several wraps of wire around both top and bottom of seal while the new ones are rubber with a copper (?) ring around the bottom only. I am assuming the design has changed over the years? I hope so, because I have already installed the new, rubber ones. Had a little difficulty in getting them down far enough - on several occasions the copper ring came off the the rubber, but I think I got them on right with a couple of tries. Any thing to be wary of here? It was a little difficult to tell how far and how hard to push the new seals down (I used a mercedes stem seal mandrel, which made the job easier). Can you NOT push the seals down far enough, or too far?

I also did not use the plastic sleeves to install the intake seals - I didn't notice any rough edges on the valves, and I found that they went on easier w/o using the sleeve, carefully pushing them initially with my thumb until they were on the valve stem flush - and then using the mandrel. Any chance I knicked them any way? I checked, but didn't visually see anything wrong.

As far as adjusting the valves, is it easiest to start with #1 cylinder and go in firing order? I should be able to adjust/check two at a time right, one exhaust and one intake?

Thanks for any input - if it hadn't been for advice from this board from previous posts (both mine and others), I would have never tried this job!

Ryan

joshhol · #2 06-08-2004, 02:37 AM

Good job on the valve stems. It went better than for you than me.
I can't really answer your questions but just wanted to congratulate you on a job well done.

One thing though, it sounds like you got the seals from fastlane, they're Elring right? The Mercedes seals might be a little different.
But I wouldn't worry bout it.

rgnprof · #3 06-08-2004, 09:34 AM

Thanks Josh,

I have had the seals for well over a year - that's how long I have been putting off this job! I don't remember where I bought them, but they are made in Germany and the package says Hebmuller technik - part #123 050 01 67.

Ryan

ctaylor738 · #4 06-08-2004, 12:16 PM

You can be organized and work from front to back, or use the firing order.

I usually do all the valves with their heel on the rocker, turn the engine, do some more, etc. I keep a list and check them off as I go.

rgnprof · #5 06-08-2004, 07:36 PM

Chuck,

I did them as the cam rolled around into position and checked them off a chart. Not bad, got it started and it sounds different! (I had to reset the timing and the idle speed). I don't know for sure but a good mecahnic friend told me to err on the side of being too loose rather than too tight. The feeler gauge pulled out with very little resistance, but there was some. The manual says a tight fit and I am pretty sure mine is not a tight fit (hard to tell for me though, this is the first time I have adjusted valves).

All of the valves, or almost all were too tight at the start. What do you think? Is it a problem to have the clearances too great (too loose)? I set the intake at .003in and exhaust at .008in per the emissions plate on the car and the shop manual. Thanks.

Ryan

ctaylor738 · #6 06-08-2004, 10:03 PM

You done good. It is pretty common for mechanics to set the valves on the tight side because this tends to keep the noise, which was a frequent complaint, down. As long as you set them to spec and to similar clearances, you will be fine.

rgnprof · #7 06-08-2004, 11:57 PM

Thanks, I think I will drive it for a few days and see how it 'feels'. I definitely can hear the difference - seems to be a little more knocking coming from the engine, but I haven't driven it any yet. Just a little concerned about whether I got them too loose and if it could hurt anything.

If I have to readjust them again, having done it once I think it will go a lot quicker (now that I know a little about what I'm doing).

Ryan

psfred · #8 06-09-2004, 07:33 PM

Better loose than too tight -- too tight and the valves don't seat completely. They will eventually burn --- $$$$

I need to do both jobs on the 280, but it's gonna wait a while, too many other things to do first. Exhaust most likely, now that I can hear both mufflers leaking.

Pete

rgnprof · #9 06-09-2004, 11:45 PM

Well, I think I'm finished. Checked the valves again this morning and readjusted them a little tighter (but they are definitely not too tight). It helped to checked the clearance with a second feeler gauge - just the next size up. All were a little too loose and it sounds better and runs great. I'm not sure I fixed the white smoke on startup - it is better but I did notice some smoke when I started it up on one occasion this afternoon. The intake seals were fine but all of the exhaust valves were hard and brittle - trouble is I'm not sure that I got all of the new rubber exhaust seals down far enough on each valve. I may have to check them again. Overall, I'm pretty pleased - but I need to drive it some more. Without any frame of reference it was just a little difficult to figure out how far down the valve stem the seal was supposed to go. I tried to put them back where the old ones were - but hard to see sometimes for sure.

Ryan

rgnprof · #10 06-10-2004, 06:53 PM

After driving it today I have noticed some smoking - only on startup and only sproadically. Not as bad as before and not as consistent, but still there. I checked the AT fluid, thinking that I still could have a sporadic vacuum modulator problem and I noticed that there is too much AT fluid - about 5-10 mm above the highest mark on the dipstick. Is it possible that the modulator problem could be sporadic, or does it either work, or not work?

The shop manual is very clear about not having too much fluid - could having too much be causing some of my intermittent smoking problems?

What transmission fluid should I use? I am planning on changing the fluid and filter in the next day or so. I haven't changed the fluid in the year and a half that I have owned the car (15,000 miles or so). Thanks.

Ryan

joshhol · #11 06-10-2004, 10:24 PM

I wouldn't think vac mod would cause smoke at startup. Also, note the smell, tranny fluid will smell sweeter than burnt oil. Could only take a couple bad guides to cause smoking, how many miles on the engine?

I put Mobil synth atf in my 115 with no noticeble problems. Other than that, I personally would use the chevron atf, no other reason than I like delo. My 0.02

rgnprof · #12 06-11-2004, 10:11 PM

The engine has approx 165,000 miles, but I know the head has been worked on before - valve job, etc. I couldn't find anything wrong with the guides while I was changing out the valve stem seals. They are were tight.

I am a little disappointed though - after drving around today I still have the smoking problem (puff a white/blue smoke on start-up only and it smells like oil to me though I'm not sure). Leads me to 2 possible conclusions - I didn't install the stem seals correctly or the smoking is coming from something else. It does it worse the longer the car sits between starts - usually worst the first thing in the morning, but will smoke - at times - throughout the day. I have checked the compression on a couple of occasions and haven't noticed any problems (previous posts), so I'm not sure what's going on. I know I should just live with it, but I'm a little obsessive-compulsive! Car runs great and I am probably using a quart of oil every 1000 miles, or so. Thanks.

Ryan

psfred · #13 06-11-2004, 10:48 PM

Ryan:

Seals get pushed down until they lock into place. It isn't possible to push them down too far, they fit over the "boss" on the valve guide and seal at the top surface there.

Bad modulator will do exactly what you see, gradually getting worse. Pull the vac line and check for oil.

All MB's after 1969 take Dextron fluid, any brand. Synthetic works very well, and will probably extend the life of the tranny quite a bit.

Peter

rgnprof · #14 06-12-2004, 11:58 AM

Peter,

Thanks for the reply - I am thinking I may have not got some of the exhaust selas down far enough??? I am attaching some pictues of intake guides, exhaust guides and the tool I used to install. The intake seals were hard teflon, and while I did not hear them 'lock' in place, I pushed them down as far and as hard as I could. The exhaust seals were rubber and I'm not sure. I used the same tool fro both seals although Mercedes sells one for intake and exhaust seals (9 and 11 mm respectivley, I think). I think the one I have is 11 mm for the exhaust.

Looking at the exhaust guide, I'm not sure how far down the seal goes? And does the intake seal go over the first ridge and fit snug against the ring/boss about half way down the guide?

Sorry if I'm being difficult - just never done this before and I want to make sure I am doing it right. Thanks for the help.

Ryan

rgnprof · #15 06-12-2004, 11:59 AM

intake guide: