M116 Timing Chain guides
 

Bought a 1990 420SEL a couple of months ago with 96,500 miles. The PO had replaced the timing chain and guides back in 2004 at 73,000 miles. I was worried about the guides as it has not been a lot of miles, but 15 years has elapsed. Doing a bunch of research and look at videos made me very worried that the guides would be bad.

I borrowed my airplane mechanics’ borescope and took a look inside the motor. Luckily the guides still are mostly white with a slight discoloration. What does the group think?

Thanks for your input.

Stephen

I think you'll be OK. Those haven't turned dark brown yet. They likely haven't seen many heat cycles either. Make sure those cam oiler tube clips look Good..not everyone changes them when they do TC & rails


Also make sure what ever oil you are running hasa zinc count 1200 ppm or Above! The rocker/cam geometry creates a LOT of force at that mating surface.

Jono

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Thanks for the reply.

After I bought the car and changed the oil, I added some automotive camguard (aslcamguard.com/) to the engine. I have used the aviation blend of camguard in my Continental IO-550(Cirrus SR-22) with good results. I use the diesel version in my 1984 300SD. When I change the oil again in the SEL, I will send a sample to blackstone and see what the report says.

Stephen

Thats about what they look like on my 420SEL and they were changed in 2001 and have about 90k on them.....

That 22 is a fun one!


Brad Penn 20/50 has been our pre-95 go to oil ever since everything started to get reformulated years ago. Never a problem despite Hard usage!

Jono

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