Author Topic: D-Jet Or K-Jet, which one will be the last man standing?  (Read 406 times)


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I'm curious. 

From reading a handfull of posts recently, I agree that a lot, if not most of the fantastic information on this site seems to relate to K jet versions.  Much less on the D Jet.  (Perhaps the D-jet stuff is so far back in the archives that it can no longer be found easily)

So it makes me wonder,

were the w116 K jet versions the great "survivors" of the species (so to speak), and hence more information is sought and replied to?


[u]Was the D jet the quiet achiever, which still runs faithfully in the background with minimal fuss?  Hence much less information is sought for on going running repairs.  [/u]

Whilst I have a wealth of "saved" information and a variety of smaller D Jet parts engine parts on hand, I am surprised with how little I've actually had to fix/repair/replace over the journey.

Sure, I've done all the normal running gear, like bushes, shock absorbers, exhausts, radiator and the like, but the engine itself has never been stripped down ever!
The D jet system attached, whilst having required a clean and new seals many years ago, still faithfully starts and runs the car almost perfectly. 

I've Probably had more computer glitches than anything else, but even that seems to sort itself out eventually. (I have 2 in reserve!)

Eager for opinions and experiences

« Last Edit: 23 April 2021, 11:24 PM by mrkozzy »


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #1 on: 23 April 2021, 10:33 PM »
I'm sure Ryan a.k.a  "s class" will chime in here, as far as I know he works on them (DJET) for clients.
« Last Edit: 23 April 2021, 11:47 PM by daantjie »
1977 450 SEL 6.9 - Astralsilber


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #2 on: 24 April 2021, 04:34 PM »
When I bought my 450SEL it came with a Megasquirt. I threw that thing away and installed back a D-jet, bought a new MAP, new temperature sensors, a used module and harness. I had also sourced out a used trigger switch but keep a new one stored for emergency.

It has already 3 years since that big adventure but then the car runs perfectly, never let me down. Have made some 1000km travels with it and it is always fine. I can say I love the D-jet.


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #3 on: 24 April 2021, 08:20 PM »
I have to say the D -Jet is the quiet achiever. My '75 450 SEL purrs like a kitten and has quick response to the go pedal.  The only problem I had was a fuel pump replacement and the filter but I put that down as wear and tear and not really a D-Jet problem.
What this country needs are more unemployed politicians.
Edward Langley,  Artist (1928-1995)


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #4 on: 27 May 2021, 10:41 PM »
I've had a K Jet 450SE and currently have a D Jet 280SE. What I can confirm is the performance difference between the 450SE and the D Jet 280SE is minimal. The D Jet 280SE is no slouch at all. If anything, off the line it's probably quicker; the shorter diff helps with that, but there's no shortage of power. I'd take a D Jetronic - I feel like it makes for a better performance.
1975 Mercedes-Benz 280SE
1981 Mercedes-Benz 300D
Previous cars:
1979 Mercedes-Benz 450SE
1982 Mercedes-Benz 280E


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #5 on: 16 June 2021, 02:39 PM »
I'm a little surprised - I've always heard that D-jet is a ticking time bomb before an engine fire, and K-jet is a rock-solid and trusty system that had only the minor drawbacks of being thirsty and the occasional tuning session is fussy.

I worked in a German indie shop while in college, it was a BMW-themed shop but we had just as many MB's coming in as Bimmers, and everyone lauded K-Jet (or CIS as they called it), and they really hated D-Jet.

If we ignore the possibility of leaking fuel injectors and fires, and faulty modules, is D-jet actually a good system? I don't really know anything about it.

What I know about K-jet is that it's a self-contained mechanical unit on the engine that distributes fuel, and even if it's out of adjustment it will work. Getting it adjusted or serviced is the tricky part because it's complicated (needs tools, knowledge, parts, etc).
'75 280S
'77 6.9
'82 300TD


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Re: D-Jet Or K-Jet, which one will be the last man standing?
« Reply #6 on: 17 June 2021, 12:40 AM »
 D jet is the better mousetrap.  It only got overtaken  by K jet in the pursuit of environmental /emission pursuits. D jet is a performance set up.
A back to back comparison of a 450 V8  on D verses K does present a useful performance difference.  quoted HP ratings by DB reflect a measurable difference. I'v e often wondered what a 6.9 would have been like on D jet.
For an early generation electronic system, she was ahead of the curve,.has proved to be reliable..bit expensive to maintain now [injector costs plus a few hairy electronic boxes]  and they get thirsty when pushed.
The K jet is the product of a crazy theory which was  proved could work. I am constantly amazed at how this whacko system was ever contemplated............The D jet is simple.
the K jet is a miracle.  It went on to see service in so many applications and has proved to be pretty reliable. It's only when KE came on the scene that it it became cranky!! ::)
btw.........if you want to get a sense of real throttle response, try a euro 6.3 on the old mechanical injection.