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 ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-04-2003, 01:07 PM
RobertG
Guest
 
Posts: n/a
Question Timing Chain takes out another 420SEL

Timing Chain takes out another 420SEL

Last week the Timing Chain on my 1986 420SEL with 212K miles skipped when my wife tried to start the car. She did not notice any loud or unusual sounds while trying to start our 420 just that it would not start. When I arrived home from work I tried to start our 420 but it would not start and would just turn over as if there where no spark.

I had the 420 towed to the MB dealer. After inspecting the timing chain, pulling the left valve cover, and a compression test they reported that the timing chain skipped and that there is evidence that some of the vales bent on the left side. (The result of the compression test (cyl:psi): 5:0, 6:0, 7:0, 8:0, 1:75, 2:125, 3:100, 4:125.) They stated they could rebuild the top end but that could cause problems with the bottom end.

The 420 was my fatherís car and I would really like to keep the car but Iím not sure about the condition of the bottom end. Additionally before the timing chain problem the car was leaking oil and the AC had gone out. If I have the top end rebuilt I still have the additional costs to take care of the oil leak and AC.

Questions:
1. Does the result of the compression test give any indication of the condition of the bottom end?
2. Does the leaking oil give any indication of the condition of the bottom end? The oil leak appears to be coming from the main seal but the leaking could be from other places as well.
3. What should the psi rating be for an engine in good condition?
4. Any general advice?

Thanks for your help,

Robert
Reply With Quote
  #2  
Old 01-04-2003, 01:20 PM
asiamood
Guest
 
Posts: n/a
If you are considering any engine work on this vehicle I would STRONGLY recommend you find an experienced, reliable, independent Mercedes shop rather than using the dealer. It will save you a ton of money!
Reply With Quote
  #3  
Old 01-04-2003, 01:40 PM
PaulC
Guest
 
Posts: n/a
I'd love to know how repairing the top end would have a negative effect on the bottom end. My BS detector is making a few faint ticks.
Reply With Quote
  #4  
Old 01-04-2003, 01:51 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
My shop has done hundreds of these repairs. There is never a problem with the bottom end. I have one customer with 650k miles on one (91 420SEL) and we have done two of such repairs to it. I felt bad when the first came back after only 120k broken again. It turned out that when we did the first one with what we thought was 150k it was really something like 300k (speedo had been replaced). When it got somewhere over 400k true it wore through the lower left side rail. When we did the first one we didn't go for that rail because it doesn't wear out till after 350k.

He has over 200k on it since the second repair and he repainted it a while ago so I guess he is going to use it another couple years (he drives 90k miles a year).
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #5  
Old 01-04-2003, 02:04 PM
Super Moderator
 
Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,316
The important things for the compression are to be adequate and even. I don't have 420 information is front of me, but you would certainly want to see 125 +/- 10%.

If oil consumption is reasonable and oil pressure is good, the bottom end is probably OK.

The right side is clearly hosed with bent valves. The left side has a couple of low readings. You have to fix the right side to get the car to run. I would think you are looking at another 3-4 hours of labor plus a few hundred dollars at the machine shop to do the left side.

I would say that this (both sides) is the minimum investment if you are going to keep the car. If you decide to sell it just do the right side and have some XP33 run through the engine to see if you can improve the compression.

There used to be a saying "If you valve, you've got to ring." The theory was that good compression would put pressure on worn rings and cause additional oil consumption. But I haven't heard anyone say that about the later Mercedes V8's.

My $.02
__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
Reply With Quote
  #6  
Old 01-04-2003, 03:35 PM
it leaks, its german
 
Join Date: Mar 2002
Location: raleigh nc
Posts: 1,111
As long as a 116/117 has not been run hot, the bottem ends are damn near indestructable.


Fix it, it'll be fine.

Just get a good indy to do it and go buy a widescreen with the money you'll save.



Joe
__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364
Reply With Quote
  #7  
Old 01-04-2003, 08:58 PM
ILUVMILS's Avatar
Senior Member
 
Join Date: Sep 2002
Location: New Jersey, U.S.A.
Posts: 2,461
Am I missing something ? Who does a compression test on a motor with bent valves and cam timing off? I hope you're talking about a leakdown test, but the numbers posted don't sound like it. In any case, pull the heads and see what's broken. I've never seen a jumped chain hurt anything in the bottom end of a 116.
Reply With Quote
  #8  
Old 01-04-2003, 09:24 PM
Gilly's Avatar
Registered User
 
Join Date: Mar 2001
Location: Evansville WI
Posts: 9,616
I have to agree with ILUVMILS. If the timing chain is toast and the one bank jumped time, THAT'S probably a good indication to say, uh, STOP cranking the engine over.

Gilly
Reply With Quote
  #9  
Old 01-04-2003, 09:43 PM
Moderator
 
Join Date: Dec 2001
Location: Southern California, U.S.A.
Posts: 8,508
Robert, you are one lucky guy!

You make your very first post, and got four good replies from four different Mercedes technicians, one after the other! I've never seen anything like it.
__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".
Reply With Quote
  #10  
Old 01-06-2003, 11:39 AM
Registered User
 
Join Date: Jan 2001
Location: Cedar Rapids, Iowa
Posts: 63
Unhappy 420 chain, too

The problem is famous enough to be in a magazine: http://www.import-car.com/ic/ic40024.htm
Mine, two years ago, broke one valve and took out a piston. I'm just now putting in a short block and correcting all the screw-ups my "low-cost independent" incorporated in repairing it. I've drilled out eight socket heads, found the intake gasket was leaking and discovered broken spring shims in one head. Make sure you get references from someone who has had major work done, not just tune-ups. Good luck. By the way, Auto Sports Unlimited in Zeeland, MI, offers this engine remanufactured at a reasonable cost as well as remanned heads. Compare it against repair of yours. I found out I could have replaced mine cheaper.
__________________
Gregga
'89 420 SEL "Moby Dick"
'30 Ford Coupe
'31 Ford Slant Windshield Town Sedan
'33 Ford Pickup
'34 Ford Pickup
'01 Honda Passport
Reply With Quote
  #11  
Old 01-06-2003, 06:12 PM
cobra
Guest
 
Posts: n/a
There is a big difference between a low cost indy and a knowledgeble indy. Make sure you find the latter.
Reply With Quote
  #12  
Old 01-07-2003, 01:04 AM
asiamood
Guest
 
Posts: n/a
I agree with what Ned said. Cheaper does not always mean better. The MB dealer in my area gets around $83 USD per hour and my independent mechanic who has specialized in Mercedes/Porsche for over 25 years charges around $62 USD per hour. The indy always tries to get parts from junkyards for older MB's to save me money where the dealer always installs new. Unless the car is still under warranty I will go to my independent shop every time. In my case, my independent guy is cheaper and better.
Reply With Quote
  #13  
Old 01-07-2003, 09:16 AM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
There are lots of reasons to choose a competent independent. The nomenclature describes the reason. He is independent. This means all techniques are accessible including factory approved methods.

This independence allows all sorts of repair techniques not suggested by the manufacturer, including used parts, non OE parts, improved parts (parts redesigned for handling, horsepower, longevity, etc). It includes repair techniques including A/C hose repair (here again the independent can improve on the part by rebuilding hoses with barrier hose where new would be the same old R12 junk), TIG welding, machining, electronics soldering and repairs.

Generally rebuilding of any nature has been discouraged at the dealer level. If one chooses the dealer level of repair the point of obsolecence is reached at a much younger age. Obsolecence being the point where repair costs make new purchases economical. Sort of in their best interest not to lengthen that time span.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #14  
Old 01-07-2003, 10:48 AM
Super Moderator
 
Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,316
I agree. From practical standpoint, you would have to be Bill Gates to afford a repair like this (chain and heads) on a 420 at a dealer.

But you do need due diligence. Look at the recent post from chrisgoodman with his valve train problems.
__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
Reply With Quote
  #15  
Old 01-07-2003, 08:08 PM
Registered User
 
Join Date: Jan 2001
Location: Cedar Rapids, Iowa
Posts: 63
420 cams

On a related note, how do you time the cams? My Mitchell manual mentions doing it but doesn't describe it. I'm putting in a short block and need to start from scratch. The only timing mark referenced is on the distributor drive gear.
__________________
Gregga
'89 420 SEL "Moby Dick"
'30 Ford Coupe
'31 Ford Slant Windshield Town Sedan
'33 Ford Pickup
'34 Ford Pickup
'01 Honda Passport
Reply With Quote
Reply

Bookmarks

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




All times are GMT -4. The time now is 05:40 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page