Timing Chain Guides, Metal or Plastic?

[JohnnyC]

Greetings, I'm in process of an engine rebuild and I was wondering what are some opinions about the plastic timing chain guides.  I am preferring the metal (aluminum) guides instead of the plastic. Seems like the plastic material would not hold-up to the stresses and temperatures that the guides are subjected to. This is for an M130 engine, '70 280SL. There are three total guides, one long and two short. Thank you!

Cheers and God Bless,
JohnnyC

[ctaylor738]

I vote for the metal guides.  I have seen the consequences of broken plastic guides on M115 and M117 engines too often.

CAT

[JohnnyC]

Thank you for confirming my thoughts. I’m surprised this concern doesn’t come up more often on the forum. Since my metal guides look to be in very good condition, I’ll use them.

Cheers,
JohnnyC

[Benz Dr.]

Don't be confused. V8 engines have much longer chains which eventually grow longer with use. Those longer ( loose ) chains beat the plastic chain rails to pieces. It's not the guides that fail, it's the loose chain that makes them fail.

[ctaylor738]

I politely disagree.  A couple of months ago, I was changing the valve cover gaskets on a 65K mile 560sl.  The chain was nice and tight, no noise.  But one of the rails had cracked where the pin goes through.  Replaced the rail and probably saved the owner a lot of pain, as we were prepping the car for a cross-country trip.

[Benz Dr.]

I politely disagree.  A couple of months ago, I was changing the valve cover gaskets on a 65K mile 560sl.  The chain was nice and tight, no noise.  But one of the rails had cracked where the pin goes through.  Replaced the rail and probably saved the owner a lot of pain, as we were prepping the car for a cross-country trip.

And I'll politely agree. But they are two very different engines which is my point to begin with. Those plastic top chain rails have tendency to break and seem to be a common problem on those engines, not our 113 engines.