Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 07-28-2001, 08:50 PM
Posts: n/a
I've just purchased a 91' 420 SEL with 101,000 miles on it.

After reading the archives regarding guide failures, etc, I've acquired a very nervous feeling about the risk of driving it any further without getting it into a mechanic to check it out(which I plan to do in a few weeks).

However, I have a vacation planned tomorrow in which I really wanted to take the car out, forgoing cramming the family into the truck. I'd be putting on about 600-700 miles.

Would it be taking too much risk to drive it another week?

Is it unusual for the failures to occur at 100k or less, relatively speaking? Any thoughts on, at what mileage, failure typically occurs?

The car idles fine and no unusual noises at startup. Maintenance records thru 80k indicate very frequent oil changes, etc.

P.S. - And this is a great forum, thanks in advance for any opinions/thoughts.
Reply With Quote
Old 07-28-2001, 09:03 PM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 12,032
I would take the 420SEL

on the vacation and enjoy the ride then get it taken care of when I returned. If the oil has been changed often up to 80k miles then it should be fine. It is my opinion that the care given to a car the first 100k miles determines really how long the car will go. I had a 1986.5 Nissan 4 cyl pickup truck that I changed the oil at every 3k miles and sold at around 65k. I saw it the other day and it is now showing over 280k miles and I know they have never touched the timing chain.
Reply With Quote
Old 07-28-2001, 09:08 PM
Registered User
Join Date: May 2001
Posts: 301
How handy are you? You could take off the valve covers and check the condition/color of the guides (white-light = good. amber-dark=bad) I sugjest you replace the valve cover gaskets if you do this.

I personally would not risk it without at least checking the guides, too much downside risk. I got mine done in the nick of time. If you live in SoCal I know a great mechanic.
Reply With Quote
Old 07-28-2001, 09:43 PM
Posts: n/a
i need a mechanic

fred segal, i'm in so. cal. Which mechanic can you refer me to and where is he located? I need to get the timing chain done also. Thanks in advance.
Reply With Quote
Old 07-28-2001, 10:01 PM
Posts: n/a
If you are handy with a wrench you may want to check this out yourself. Remove the valve cover that is handiest and rotate the engine with a socket on the dampner bolt head. Follow the normal direction of the engine rotation (look at the cooling fan blades). Carefully rotate steadily with constant pressure until the cam mark lines up with the cam tower mark. Note the indication of timing on the dampner wheel (you may need to do this several rotations until the cam mark lines up and the dampner marks are visible, remove spark plugs to unload compression and engine will turn easier). After you have determined a timing mark on the dampner, reverse the direction very slowly until the cam start movement in the opposite direction, note the position of the dampner timing mark. What is the difference. There is no set amount of allowable play that is published but I would not like to operate an engine with over a 5 (I have read 10) degrees difference.
Reply With Quote
Old 07-28-2001, 10:43 PM
Paul Rondeau
Posts: n/a
You might want to have it checked out for peace of mine!
I've seen those chains break at less miles than a 100k
The left upper rail is the big target point for breakage.
As far guides go unless the plugs have some oil deposits
on them i would'nt worry to much about them.Those were
good motors if well maintained!



Reply With Quote
Old 07-28-2001, 10:47 PM
Posts: n/a
Paul, I am confused. What plugs affect a guide?

Nevermind, I thought you were talking about the chain guide rails, not the valve guides.
Reply With Quote
Old 07-29-2001, 01:55 PM
Registered User
Join Date: May 2001
Posts: 301

The shop is called Mr.MB Motors and it's in Tarzana. I was just there on Friday,because my shifter was making a metalic sound. Enrique put it up on the lift and changed both bushings, no charge (he said I should buy my daughter a present) I'm not saying he will do free work on your car but I promise you will feel this is the best money you ever spent. Enrique will repair your car and give you the pease of mind you wish the dealership could deliver.
Reply With Quote
Old 07-29-2001, 03:26 PM
R Easley
Posts: n/a
420 SEL Timing chain/guides - failure risk

The timing chain rail breakage on the 420s would be described by anyone as a catastrophic failure and, as such, you can't really put a time limit/mileage range around it.

Some have said that frequent oil changes mean that you shouldn't worry; others have said look at the color of the guides. No disrespect meant here whatsoever, but a catastrophic failure is a catastrophic faiure. Another example that has been discussed recently on this list is the single row timing chain in the 3.8 engines. One could change oil every 500 (five hundred) miles in this engine and yet, you are still "rolling the dice" on continued driving with the single-row chain. Same with the problematic guide; a less-than-$5 part in this case . . .

I would venture a guess that the major explanatory factors for guide failures are the number of hot/cool cycles and the amount of in-town driving, because we're talking about a plastic guide here. The only reliable visual in my mind would be hairline stress cracks; I know that several have seen this evidence on guides. Color to me would provide minimal information unless it is near black.

Consequently, back to the original poster's question: "Is the car safe to drive on vacation?" As someone has already pointed out, guide failure is unlikely to occur in this 6-700 mile interval. However, life is a series of risk assessments. You have a known catastrophic failure for your specific engine. How much risk are you willing to assume for this known problem?

Richard Easley
Waco, Texas
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Power Steering Box - 420 SEL Hans47 Tech Help 20 04-08-2004 12:11 PM
How involved is replacing the timing chain guides on an 89 420 SEL 96C220 Tech Help 6 11-13-2002 02:13 AM
W126 420 SEL Dome light diagnosis help... 96C220 Tech Help 14 11-07-2002 02:11 AM
420 SEL - Check Engine Light Codes Needed. rsamson830 Tech Help 1 10-30-2001 08:34 PM
Timing Chain, 72 280 SEL 4.5 Deezel Tech Help 4 06-12-2000 07:19 AM

All times are GMT -4. The time now is 05:25 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page