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.

[colin evans]

No need to remove the head for this

[Pinder]

i did this using the rope method, I felt it was less risky than using compressed air.

[Bonnyboy]

I haven't had to do the VSS on my pagoda yet but just did them on my '65 F100.  My hint is to go with a larger diameter of rope so that it stays rigid and will get down the hole once its oily and flexible  -  Stay away from a Sisal or Manilla rope as they will leave threads and go with a fine thread nylon or cotton.  I wasn't happy with polypropylene either.

[silver surfer]

Thanks to all for your great advice.
After reading the comments I think it would be worth removing the head in order to check the valve guides.  I have a Haynes manual and have removed the ancillary items from around the head.

[WRe]

Hi,
I hope you have already gotten the correct cylinder head gasket.
...WRe

[silver surfer]

Thanks to all for the great advice. I think it is worth removing the head to check the valve guides.

I have a removed the ancillary items from around the head and the chain guide at the front with the two Alan bolts, however,  the Haynes manual is not clear to me how to remove the left hand tensioner shaft and sprocket in order access the Alan bolt beneath. ( see photo)

Any advice would be most welcome.

Many thanks.

[ja17]

An experienced tech, with the proper tools, can install the valve stem seals with the head on the engine in three or four hours. If you go to all the work of taking the head off, it should be disassembled and reconditioned. Replacing valve seals rarely is the permanent solution for oil usage or smoking. The valve guides tend to wear with time and mileage. In addition, the new valve seals will have more difficulty staying in place on the old worn guides which are worn smooth on the outside. It might still be worth a try, but if you take the head off, get it re-conditioned.