Author Topic: Renew valve stem seals: A field report  (Read 1838 times)

WRe

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Renew valve stem seals: A field report
« on: October 01, 2022, 09:52:04 »
Hi,
I have renewed my valve stem seals (VSS) with the cylinder head installed in the last few days and do not want to withhold MY experiences from you. However, they should only serve as supplements to
- Joe Alexander's thread: https://www.sl113.org/forums/index.php?topic=1113.msg5541#msg5541
- Klaus Falke's report: https://www.pagodentreff.de/diskussionsforum/pages/ventilschaftabdichtungen230sl/and
- Roadbook's report: https://w113.eu/closed/Reparaturen/ventilschaftabsiegelen Mercedes Pagode W113.htm

Time required: A total of approx. 10 hours, approx. 20-60 minutes per valve, in pairs, because 3 hands were sometimes necessary.
Required tools: valve tensioner (original MB tool; as already mentioned in the Roadbook report, the tensioners shown there do not fit because it is too tight; the original MB valve tensioner has hooks, here a wire rope because the hooks are missing, which is easier, but it also worked with the rope), compressed air and adapter for spark plug threads, impress tool, Geisfuss for adjusting the valves and removing the rocker arms, magnet lifter to lift the valve cones out.
Material: Elring valve stem seals. Viktor Reinz's are identical. Unlike my old white nylon/wire VSS, the new ones for the exhaust valves were brown Viton.

As a safety measure I fixed the camshaft with a 22mm ring spanner and some wire, as I noticed that the piston kicks back when you apply full pressure (5-6 bar) straight away. Better to let the pressure build up, then that didn't happen. I also sealed the space around the timing chain with a rag so nothing can get lost there.

The removal of the rocker arms with valve spanner tool worked on the exhaust valves without changing the valve clearance. The clearance on the intake valves had to be significantly increased in order to be able to remove the rocker arms.

In contrast to the reports and also to the Workshop Manual, the valve cone halves sat with me as if welded on the intake and not the exhaust valves and could only be loosened with many hammer blows. You can actually hear it when they've come loose. That's where most of the working time went with a variety of methods. It worked best with a 1/4" socket with a long (to get past the cams) 6mm Allen key attached, cut off, as the socket just fits into the valve plate.

The VSS were relatively tight and, due to the lack of pliers, could not simply be levered off. Care must also be taken to avoid scratching the valve guides. But if you reach under the valve rotator with a screwdriver, you can easily push the seal up with it.
You will need a tool to press on the VSS as they are very tight as they should be.

When assembling, handle the valve cones carefully (nose-nose pliers for inserting), otherwise they will disappear in the engine compartment and you may lose a lot of time.

...WRe

« Last Edit: October 02, 2022, 07:00:40 by WRe »

MikeSimon

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Re: Renew valve stem seals: A field report
« Reply #1 on: October 01, 2022, 14:08:40 »
Description is appreciated and probably helpful to those who want to take short-cuts, I have NEVER replaced valve stem seals on any motor with the cylinder head installed, however.
1970/71 280SL Automatic
Sandy Beige
Parchment Leather
Power Steering
Automatic
Hardtop
Heated Tinted Rear Window
German specs
3rd owner