Author Topic: M116.985 versions and engine number series  (Read 141 times)

Berggreen

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M116.985 versions and engine number series
« on: 13 August 2020, 12:10 PM »
Hi All

I have a 12/1977 350SE with the engine number: 116985-10-001516, thus a European first generation K-jetronic with 195HP. The car originally had manual gearbox, but it was converted to an automatic by Mercedes in 1990.

I have been offered a replacement engine, which is sourced from a 350SLC which the seller claims is from 1981, and the engine has the number: 116985-12-014547.

So my questions are:
1) Which engine is the replacement, I have been offered? Is it from a US or European car in terms of compression?

2) Does this engine fit into my 350SE? Do I need to do any modifications?

3) I know that a new generation of the 985 engines with 205HP (compared to the 195HP in the first generation) was introduced in 1978. But where is the split between the two generations in terms of engine numbers?

4) What is the differences (apart from the performance), between the two 985 generations? Can they be exchanged?

5) If you look into wiki for the r107, then they state that: "Fuel injection, Bosch D-Jetronic (-1976), K-Jetronic (-1980), K-Jetronic with Lambda (-1985) and from 1985 KE-Jetronic". But was the 985 engine ever produced with the K-jetronic with Lambda? Seems like neither the 350SLC or 350SE existed after 1980.

6) Looking at pictures of the replacement engine, there seem to be a plug attached to one of the injection nozzles (marked with a red ring), which looks like something from a D-jetronic. What does this do? I thought the K-jetronic is fully mechanical? Does this have to do with some Lambda sonde?

Hope you can help. :)

Thanks,

Christian

raueda1

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Re: M116.985 versions and engine number series
« Reply #1 on: 13 August 2020, 05:18 PM »
The circled thing looks to me like the cold start injector.  Hard to see exactly from the pic though. 
Sorry, can't help with the other stuff. :-\
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Type17

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Re: M116.985 versions and engine number series
« Reply #2 on: 23 August 2020, 12:26 PM »
1. The M116 was never sold in the US in a W116, and I would be surprised if the R107/C107 was ever sold with it either - it has a higher compression ratio, compared to the M117 (450), and in the 70's, high (enough) octane fuel wasn't guaranteed everywhere in the US.


2. It should be fine - the '1' after 116985 in the engine numbers means they're both for left-hand drive cars (my M116 has a '2' here, as it's a right-hand drive UK-market car). the '0' of your original engine and the '2' of the replacement engine mean manual and auto transmission respectively, but the fact that your car was professionally converted means that the '0' is effectively a '2', like the replacement engine.


3. My engine is a K-Jet from model year 1976, and is 195BHP, - all the documents I've seen show that the 1977-onwards engines are 200BHP.


4. Not sure of the exact differences, but it's probably internal stuff like cam-profiles, which won't affect exchangeability.


5. I don't think so - K-Jet was developed pre-lambda, and cars with lambda usually had KE-Jetronic or KE-Motronic (there may be exceptions, but I've never seen or read about any).


6. As raueda1 says, this is the cold-start injector, and fires into the inlet manifold for only a few seconds (the duration varies, depending on ambient temperatures). The other 8 injectors are mechanical only, opening/closing as the fuel pressure rises and falls.

Berggreen

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Re: M116.985 versions and engine number series
« Reply #3 on: 23 August 2020, 01:36 PM »
Hi raueda1 and Type17

Thank you very much for your replies. They are very helpful. :D

Cheers,

Christian :)