Replacing valve stem seals 280SL

[silver surfer]

Hi all

I would like to replace the VSS and have received the Elring kit. Is it easier to do this job by removing the cylinder head please or doing it whilst its all together?

Many thanks
 

[WRe]

Hi,
I did this job 2 years ago with cylinder head still in place: https://www.sl113.org/forums/index.php?topic=35592.msg259885#msg259885.
I think this job is easier and more comfortable with your cylinder head lying on your workbench but a lot more work. If you have a third or fourth hand I would do it my way.
...WRe

[colin evans]

Hi
I have just done this on the bench and its an easy job doing it way. The head isn't difficult to get off but it's much easier with 2 pairs of hands. Whilst it's off you can check the valves and guides for wear.
Regards Colin.

[stickandrudderman]

No need to remove the head to change VSS but you will need the right tools for the job.

[MikeSimon]

Like any repair job on a vehicle, there are always short cuts. Changing valve stem seals with head installed is one of them. The proper way to do it, is with the head off. If you want to leave the head on, it can be done if you follow a certain procedure and have a proper compressed air connection to keep the valves closed. For 99.9% of the repair/maintenance jobs I have performed myself on my cars and motorcycles, I have followed an official service manual.

[WRe]

Hi,
the workshop manual shows the way to do it: "Cylinder head installed" in German "Zylinderkopf montiert".
...WRe

[Kevkeller]

I pulled the spark plug and fed a foot or so of rope into the cylinder. Then bring the piston to the top and it crams the valve closed. It won’t move. When done pull the rope out.

Easy and cheap.

[stickandrudderman]

Like any repair job on a vehicle, there are always short cuts. Changing valve stem seals with head installed is one of them. The proper way to do it, is with the head off. If you want to leave the head on, it can be done if you follow a certain procedure and have a proper compressed air connection to keep the valves closed. For 99.9% of the repair/maintenance jobs I have performed myself on my cars and motorcycles, I have followed an official service manual.

There's nothing improper about changing valve seals with head remaining installed. I've done it thousands of times.
During the process you can observe valve guide wear and make an informed decision as to whether the guides will need replacing or not which will obviously necessitate cylinder head removal if it's found that they do indeed need replacing.
New valve seals may temporary resolve smoking issues but if the guides are worn then the new seals won't last long.

[WRe]

I pulled the spark plug and fed a foot or so of rope into the cylinder. Then bring the piston to the top and it crams the valve closed. It won’t move. When done pull the rope out.

For other engines, example here W100, they used a special lever to hold the valves in position.