QuestionQUESTION: I bought my wife an '85 380SL and I really dislike the M116 engine. I am in the middle of changing the timing chain (myself!) and don't like the complexity of the engine or the emission control system.
I found an '83 280SE in a self-serve junkyard and got the complete engine for peanuts. The car had the last owner's business card in it- I called him and he said the engine ran just fine (9 years ago) and he gave it away when the tranny quit. It still had the 159K miles on it since he last saw it , so it hasn't been run in all that time.
I did a cold compression test on it on my garage floor and got numbers like 90, 110, 120, 95, 120,115 (at about 50 degrees)- not great when this should have 150+. I could not get the engine to spin very fast- not sure if this matters in a compression test .
I would like to use this engine if the M116 in wife's 380SL ever goes bad (it has 145K miles), but I am trying to figure out how much of a rebuild it might need. I have heard that M110's bottom ends are very robust, but heads may need rework sooner. Are there any other ways to assess the engine aside from pulling the head off and examining bores? Might this engine benefit from new rings and a valve job? It would be nice to completely rebuild it, but the price of euro oversize pistons and machine shop work make me shy away from a complete rebuild.
Any thoughts as to how you would approach this?
ANSWER: The M110.98x and .99x engines are fuel-injected engines, with Bosch D-Jetronic up to the .984 and K-Jetronic from the .985. I lean to the Djet for simplicity but can be a bear to get right. The K jet is easier to get parts, but is, I think a bit more fickle. should have 185 HP , the 116 about 200 ( I think) - That aside Cold compression should not need a fast spin, and your numbers are low, could be a lot of things for an engine that has sat for 9 years+ I see no way around a tear down , at least to examine the head , valves, chain ect .
the 110 is a good engine, and if taken care of should not need top end or bottom end work any more than any other MB engine. I would speculate the 110 has some of the same complexities the 116 has, particularly in the ignition system set up and control
The 280 SE I beleive, never was imported to the states, so it is a grey market car, so some componenets varried - polution control sensors and some wireing
the 85 380 with renewed chains is a good proven engine. "underpowered" for the car is the main complaint. The 110 will make that complaint more so.
I am pretty sure the tranny will not bolt direct as well. You may want to research that
Good luck
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QUESTION: Thanks Ron-
Do you think it would help to put something like Marvel Mysery Oil in the bores and let it sit for a few weeks and repeat the compression test?
This M-110 is a K-jet from a euro W126 with no lambda sensor, no O2 sensor , no air pump and less than half of the emissions garbage on the M116. For example, in working on the M116 timing chain, I bumped off one of the fittings on the back of the throttle body and I am either going to have to do micro surgery or remove the fuel dist, piping and everything above the throttle body to get to it. The M110 stuff seems a lot more accessible.
I have no immediate plans to dump the M116, I just don't ever want to think about rebuilding it (alloy block, silicon...).
Both of the trannys are 722.3xx and I have the TC from the M110. If my wife tires of the 380SL, I have an M110 flywheel so I could convert the car to manual.
The M116 has 180 or 185 HP- We don't think it is underpowered
Answeryes that would be a good idea, and it may clean, free up things for a better test. Well I just compare the 350 to my 72 450 SL , my iron block V8 pushes 240HP, so the common complaint for those that have driven both is that the 116 underpowers the car. OF course all personal opinion.
Sounds like you have a plan, both egines will serve you well, but because the 110 is euro , you are correct , less complicated. Kjets are not my specialty, Djets are. A great manual to have is the - How To Tune And Modify Bosch Fuel Injection By Ben Watson
Good Luck
