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 > Mercedes-Benz SL Discussion Forum

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-22-2018, 11:56 AM
Registered User
 
Join Date: Apr 2003
Location: Phoenix Arizona. Ex Durban R.S.A.
Posts: 3,582
450 SL DIY question

As a general rule, of the 450 motors which is the easiest for a DIY individual to maintain? The earlier ones with the ECU (brain) running everything or the 77 and on with the mechanical fuel injection?

- Peter.
__________________
81 240D stick. 316000 miles at purchase. 342000 now
2000 GMC Sonoma
Formerly...
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles. Deceased Jan 08
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S
Reply With Quote
  #2  
Old 03-22-2018, 12:20 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 4,666
Having lived with a Euro 500SL with K-Jet for 20 years, the K-jet cars can be a nightmare to troubleshoot if you don't understand the system. "Think like a German" has never been a more applicable statement when troubleshooting the K-Jet system. Add in the emissions controls that the US models used, and I'd rather kill myself than troubleshoot a problem.
__________________
'11 Honda Accord EX - "The Daily" 64K
'83 500SL Euro - "The Money Pit" 116K
'91 350SD - "The Diseasel Jr." 168K
'86 300SDL - "The Diseasel" 189K (Totaled 1/31/19)
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Reply With Quote
  #3  
Old 03-22-2018, 03:55 PM
Daantjie
 
Join Date: Nov 2014
Location: Vancouver, BC, Canada
Posts: 93
I would take K Jet over D Jet any day of the week.
Reply With Quote
  #4  
Old 03-22-2018, 04:26 PM
Registered User
 
Join Date: Feb 2011
Location: Modesto CA
Posts: 2,749
Quote:
Originally Posted by pj67coll View Post
As a general rule, of the 450 motors which is the easiest for a DIY individual to maintain? The earlier ones with the ECU (brain) running everything or the 77 and on with the mechanical fuel injection?

- Peter.
The K-jet engines from 1976 thru '79 have purely mechanically controlled injection; 1980 has a Lambda sensor and feedback control of mixture.
The '77-'79 models had an under-floor cat, rather than engine mounted cats, and would be preferred for that reason.

Last edited by Frank Reiner; 03-22-2018 at 10:34 PM.
Reply With Quote
  #5  
Old 03-22-2018, 11:23 PM
Registered User
 
Join Date: Apr 2003
Location: Phoenix Arizona. Ex Durban R.S.A.
Posts: 3,582
I know about the cat issues. My thoughts revolve around having to maintain such a vehicle as a DIY project. Pretty much any mechanical aspect of the vehicle is similar to any other Benz of the era and ultimately could be addressed in a remove/replace fashion, wether from junkyard parts or what ever source one can find. But my assumption is that the most complex aspect of these from that era is the fuel injection system which would be the most troublesome to keep messing with on a daily driver basis. (Well, more of a weekend toy than a true daily). So that is why I'm trying to see if there is a real difference between the two systems in terms of DIY complexity. Does the later Lamba sensor addition make the K-Jet as bad as the D-Jet?

- Peter.
__________________
81 240D stick. 316000 miles at purchase. 342000 now
2000 GMC Sonoma
Formerly...
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles. Deceased Jan 08
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S
Reply With Quote
  #6  
Old 03-23-2018, 09:27 AM
Registered User
 
Join Date: Feb 2011
Location: Modesto CA
Posts: 2,749
Quote:
Originally Posted by pj67coll View Post
Does the later Lamba sensor addition make the K-Jet as bad as the D-Jet?

- Peter.
No, it just adds a sub-system that consists of a sensor, a processor/driver, and a solenoid valve (aka, frequency valve). As with all of these systems, age has its influence.

By way of a separate thought, a D-jet system converted to operation with a modern, aftermarket ECU (think Megasquirt) gets around the original D-jet limitations.

Last edited by Frank Reiner; 03-23-2018 at 10:24 AM.
Reply With Quote
  #7  
Old 03-24-2018, 09:56 PM
Registered User
 
Join Date: Sep 2011
Posts: 552
Used regularly, I’d bet an early k-jet is less prone to failure or the need for maintenance. D-jets will likely have solid lifters and points each needing adjustment. Plus other parts more prone to failure. I do like the system better than a k-jet for some reason. Something very “vintage” about maintaining it.


Sent from my iPhone using Tapatalk
__________________
Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,
Reply With Quote
  #8  
Old 03-26-2018, 09:38 PM
Graham's Avatar
Registered User
 
Join Date: Nov 2004
Location: Ontario, Canada
Posts: 3,409
Quote:
Originally Posted by fonzi View Post
Used regularly, I’d bet an early k-jet is less prone to failure or the need for maintenance. D-jets will likely have solid lifters and points each needing adjustment. Plus other parts more prone to failure. I do like the system better than a k-jet for some reason. Something very “vintage” about maintaining it.
Glad to hear you like the Djets Fonzi

One big plus for the early D-Jets, is that they don't have the plastic timing chain guides that all 107s after 1973 have. Those guides are prone to failure, sometimes catastrophic and changing them is no easy task.

I have only owned Djet. It certainly lends itself to the DIYer. Parts can be a problem - they are available new and used, but prices have been climbing. It helps to have spare ECU, MPS (manifold pressure sensor), Trigger points (or complete distributor) and AAV (aux air valve). A means of checking mixture such as a CO analyser or AFR instruments is a big help in fine tuning. Replacing ignition points with a Petronix is always a good move.

Personally, I wouldn't swap my Djet for a K-jet. May be a case of better the devil you know But really, I have had my Djet for almost 30 years with minimal problems. No shops understand them anymore, so you NEED to be a DIYer!
__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5
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 12:26 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