Long Timing Chain Rail Install

[Autobob]

I am doing a complete 280sl engine rebuild and have a new plastic style long timing chain rail ready to install. The worn OEM metal rail appears to be able to install in either direction, the plastic has a different shape on each end. Is anyone aware if it matters which end is up on the new style rail? Thank you, Bob

[Shvegel]

This is just an educated guess but I would assume plastic guide would expand from heating more than the aluminum one so the elongated hole in the plastic guide is there simply allow the plastic guide to expand.  Shouldn't matter which direction it goes in but I would install it with the round hole in the leading position.  when viewed from the front the engine turns clockwise so if the guide is on the left looking at the front of the engine the round hole would be down.

[tel76]

Are you sure the original one is no longer serviceable, a picture of the wearing face would be helpful, you would be far better refitting the aluminium one if it is still serviceable the plastic ones do not last as long and can break.

[Autobob]

tel76, attached is photo of OEM rail, top rails are both losing rubber. Rubber on bottom rail is also very hard, afraid it is brittle like top rails. Interesting feedback Shvegel. My parts suppliers don't have any feedback on rail orientation, lots of labor if it has to be redone.

[mbzse]

.../... you would be far better refitting the aluminium one if it is still serviceable the plastic ones do not last as long and can break

The timing chain must never touch the guide rail.
If it does, you have an issue with your chain tensioning device, or a worn out chain (too long). In that case, address matters immideately.
Previously discussed, see http://www.sl113.org/forums/index.php?topic=12444.msg84219#msg84219
/Hans in Sweden
.

[tel76]

Hans,
I agree with you, but the plastic ones go brittle with age and break(a known fault).

[ja17]

Yes, the originals were  better. They do not break and fall into the chain sprocket like the old plastic can when they are old and brittle.