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Old 11-12-2002, 04:52 PM
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96C220 96C220 is offline
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Join Date: May 2001
Location: Hamilton, NJ
Posts: 367
How involved is replacing the timing chain guides on an 89 420 SEL

I have been reading more and more about the rails breaking and in turn ruining the head.
Honestly I'm starting to get scared. My car has 244k on the clock, and has been meticulously maintained by the previous owner (It was a one owner car of a family friend). I got it at 242k mi.

Scouring through the 3 ring binder of service records, I cant seem to find anything relating to timing chain, or guides & rails.

The mechanic who inspected it, and has serviced the car for years, assured me that it needed nothing mechanically, and that all is well. I specifically asked him to check chain stretch and guides, which he did...

But I cant help starting to feel like im driving on borrowed time.

I would at least like to replace the rails just for peace of mind if nothing else.

I have never worked on an MB engine beyond oil changes, plugs etc... Mostly maintenance stuff. I have changed the head gasket in my younger days, but that was on my old POS Olds Quad 4 that got me through college.

I do have the w126 service cd's and I will survey the procedure, but can just the guide rails be replaced relatively easily / quickly? From what I gather from reading here, this can be done via removing the valve covers.

Can the chain be untouched... i.e. left on while the guide rails are replaced?

Are there any caveats? How difficult a job would you consider this if you were to take your time and work methodically and slowly.

Are there any special tools needed? Also how much more difficult is rolling the new chain once you are in there?

How easy is it to mess this up?

Will a new set of guide rails prevent catastropic failure for a signifcant amount of time?

Sorry for all the questions - Im just rather worried about the whole sitation. - Do I trust the mechanic? Do I do it anyway? Honestly I look at this as a learning opportunity to get more experience with the car.

This car was purchased with the idea that most things would be done DIY, but im apprehensive to jump right in to something like this.

Best wishes and take care,
George Androulakis

Former Mb's:

1990 500sl R129 - 76k Original Miles - New project - Follow the saga
1990 190E 2.6 148k mi (sold)
1989 420 SEL 246k mi (sold)
1995 C220 175k mi (sold)
1992 190e 2.6 74k original miles (sold)
2000 c230 Kompressor 122k miles (RIP)
1996 C220 149k mi (sold)
2000 C230 Kompressor Sport 127k (sold)

Current Cars:

2009 Mercedes c300 4matic
2006 Mercedes s430
2005 Jaguar XJR
2003 Cadillac Escalade
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