Author Topic: Let's talk about engines  (Read 3493 times)


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Let's talk about engines
« on: 16 May 2006, 08:18 PM »
As I understand it, the following w116 models were produced for the US market:

Car            Years          engine
280S              75-76          M110.922
280SE             77-80         M110.985
300SD             77-80         M617.950
450SE/SEL       73-75         M117.983
450SE/SEL       76-80         M117.986
6.9                 77-79         M100.985

There were other models that were only available in the European market, and there were Euro versions of the above cars which were generally the same as the US models for my purposes.

If you have a 300SD or if you have a 6.9, you obviously have a dramatically different idea of what you expect your engine to do.  It occurs to me that Mercedes-Benz put a range of engines in these cars for a reason.

I don't know about you, but I've had a tough time much finding info on our cars beyond what has been found and posted to this forum.  I'd like to read more technical evaluations, as well as just hear from people who've driven these cars for a while.  I don't know about the rest of you, but I know almost nothing about the other engines in w116s.  I know nothing about the M110 and the M617, and would like to learn more about the M100 as well as the M117 as it was available in the 73-75 450SE/SELs.

I'm hoping that people will post to this thread, and provide their year, model, and engine configuration at the top of their posts.  Tell us how many miles does your car has.

If you have a good technical article on your engine, post it or provide a stable link to it.  But also tell us what you've liked about your engine; what you haven't liked (if anything); what you've had to do service-wise since you've owned your car; how easy/hard and how inexpensive/expensive you perceive your maintenance to be; and what service/maintenance issues you perceive you need to do in the short-mid range future.  What have you heard from mechanics about what is good/bad about your engine?  What's it like to drive your car on the freeway?  In traffic?


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Re: Let's talk about engines
« Reply #1 on: 16 May 2006, 08:58 PM »
US specs

« Last Edit: 17 May 2006, 01:48 AM by Nutz »


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Re: Let's talk about engines
« Reply #2 on: 16 May 2006, 09:08 PM »
I bought my 1977 450SEL (4.5L M117.986 engine) with 124,000 actual miles on the odo and have put about 3700 miles on it since.

My US federal engine has 190 hp and produces 220 lb/ft of torque at 3,000 rpm.  [Somehow it feels a lot more powerful than my '90 Cadillac Fleetwood, which had a 5.7L/350c.i. engine that had 175 hp and produced 290 lb/ft of torque; I believe this is due to the 5 speed trans on the Cadillac vs the 3 speed on the 450SEL.]  The 77 450SEL is fitted with the K-Jetronic injection system.  Combined with the 3 speed tranny, I feel that my car has more-than- adequate acceleration (particularly considering it's moving more than 4,000 lb of weight).  At highway speeds, acceleration is magnificent; from 75mph upward, this car MOVES faster than any I've owned.  In traffic - particularly when I'm in one lane at a light and need to get into another lane quickly - there are times when I wish I had a 6.9, but for the most part  my 0-45 is adequate; I believe I have nearly as good of a 0-45mph acceleration capability as most cars on the road.   

My 450SEL was a one-owner car that belonged to a medical doctor.  I found all the service records since the car was brand new in the trunk.  Other than having the right side cam shaft, 8 rocker arms; and a new oil tube replaced at 87,000 miles, the engine has not been opened.  The starter, alternator, and all pumps on the engine were replaced - as well as the front suspension and the ACC Servo - w/in 10,000 miles of my taking over the car.
Shortly after buying the car, I realized that the original radiator was partially blocked, and installed a new radiator core.  Other than that, all I've done is a couple of oil changes. 

From what I have read on this forum's library, the M117 is an excellent engine.  The bottom ends are indestructable.  It has a cast iron block with aluminum heads.  A MBz mechanic once told me the M117 had the weakness of plastic timing chain guide rails which were MUCH more likely to break than the double-rowed timing chain (though I've never confirmed this).  Other than that, I've never heard a negative word about the engine.  I am planning to replace the timing chain at about 180,000 miles (unless I hear tell-tale clanking that tells me I need to do it sooner).  At this point, I have come to trust that my engine is in good working order; it is currently my only car.

Thus far, I've found parts have been more expensive than standard US parts - but internet shopping has kept things reasonable.  I'm learning more and more about mechanics and auto-electric in order to do more of my own work.

My only projects at this time for my car are: 1) replace my brake master cylinder; 2) fix the switch for the right rear window; 3) fix the power door lock for the right rear door (it doesn't properly lock the car after very short drives); 4) do some ACC system work from the console; 5) grease the sunroof rails.
« Last Edit: 16 May 2006, 10:22 PM by michaeld »

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Re: Let's talk about engines
« Reply #3 on: 16 May 2006, 11:46 PM »
I am a very proud owner of a 280SE 116.024 with M110.985 EURO here in South Africa.  It has been my daily driver for 10 years.  Odometer shows 423 000km, anthough I suspect the previous owner of haircutting it and the true mileage is believed to be nearer 500 000km.

In South Africa 280SE's are far more plentiful than 350SE's. Ten years ago I decided to shop for both, and buy either based on the condition of the individual. I ended up with a 280SE. It turned out to be the right choice for me as I was a student at the time I bought the car and finances were tight. It has also served me well as reasonably economical transport which is important considering the mileages I do.

Well, economical is all relative. Over the years I have found that when well tuned, the 280SE uses 14l/100km on the open road and 15 to 17l/100km in urban cylce depending how hard I drive.

I have replaced or overhauled almost everything on the car.  As an indication I have done the following (only listing major work)

Mileages listed are what the odo said approx : bear in mind it seems the previous owner could have trimmed as much as 100 000km off, so you could add 50000 to 100000 to these mileages :

complete engine rebuild : 257 000km
fuel distributor rebuild : 260 000km
geabox replacement : 313 000km
front suspension rebuild : 395 000km
fuel injector replacement : 320 000km
A/C system overhaul including new compressor : 375 000km
fuel tank overhaul : 405 000km
brake system overhaul (calipers, hoses, master cylinder, servo) : different bits done at various times between 250 000km and 375 000km
rear drive shafts :
left at 300 000km
right at 360 000km
left again at 385 000km
power steering recirculating ball box : 220 000km

shock absorber replacement :
front : every 75 000km
rear : every 40 000 to 50 000km (I often carry heavy loads)
brake pad replacement :
front : every 15 000 to 25 000km
rear : every 100 000km

tyres : 1 set every 50 000km
rear tyres can either last less than fronts, or double the life of fronts depending on how hard you generally accelerate

Service items :
engine oil and filter change : every 8 000km
gearbox oil and filter change : every 35 000km
spark plugs : every 25 000km
air filter : every 25 000km
high pressure fuel filter : every 40 000km
radiator flush and refil : every year
diff oil change : every 100 000km
drive shaft service and refill : about every 10 years
tappet set (M110 motor only) : every 25 000km
power steering filter and fluid change : every 100 000km

Other miscellaneous items replaced at various times :
rear wheel bearings, exhaust, steering coupling, various electrical relays etc etc

When I was shopping around 10 years ago, most of the 350SE's I drove were not in good condition so they left a disappointing opinion of the power - and they appeared to offer little benefit over the 280SE. Back in the late 1980's my dad was wanting a W116 and drove a lot of 350's and 280's - remember the cars were only 10 years old then. He recalls that good 350's were really potent and a worthwhile improvement over 280's. He also commented that the 350 engine seemed to rev quite fast for a v8 which gave the car a lot of character and perhaps "soul" - ie it had all the right sound effects. Personally though I still prefer the wail of the 280 twincam. When its properly sorted it will EASLY run all day at 5000 rpm and is quite happy to reach its redline of 6500rpm - although I seldom do this.

A W116 always makes me feel like a king, although my W116 is a modest 280SE auto but with all the nice options like black leather, aircon, power windows, central locking, rev counter etc.

I still look at W116 with total admiration. The lines are timeless and the build is almost indestructable. It inspires confidence in a familiar driver. It may take some time to get used to driving - it can feel a bit wallowy by modern standards. With my combo of Bridgestone Turanza GR50 in 205/70HR14 and the best gas shocks, plus rebushing the entire suspension I can attack sweeping bends on back roads at crazy speeds in total confidence.

In my business I often travel on bad back roads at night usually against time pressure. The W116 has been my vehicle of choice for these conditions.

The M110 280 engine is a work of art. The euro versions are nice and torquey and fairly economical. They have a very very special sound to them at night blasting along when the revs get over 4500 or so in top gear. Its kind of like a mournful wail that stirs my to the very fibre of my being. Picture this - on a back road at night doing 140 km/h and the motor at 4200rpm.  come up on a slow moving truck causes me to drip to 90km/h - just kick down and leat the motor wail up to 6000rpm as I shoot past with the speed rising to 120, 130 and then back to 4th gear.  Causes a big smile. 

So I have driven this 280SE all this time because for me NO other car that I could afford comes even close to the blend of performance, comfort, safety and STYLE. Really thats what S class cars are about. And the W116 has buckets of it - presence and class.

My other favourite with the 280SE euro is the 4 speed auto box.  The ratios are just beutifully matehced to the M110 to give the car its character.  I've set mine up so that even under full throttle take-off it moves off in 2nd gear.  Lots of torque and the car surges away.  Manually shifting into L for a 1st gear take-off is basically unnecessary.  That changes the surge to a leap. 

The 280SE auto euro now feels slow to me when I first climb into it after driving my 500SEL W140, but that only lasts for a few mins then it feels great again.  It can have a personality that is relaxed or impatient according to how I feel. 

Cheers, Ryan in South Africa

'76 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '82 500SEL euro full hydro, '83 500SEL euro full hydro , '81 500SL

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Re: Let's talk about engines
« Reply #4 on: 17 May 2006, 12:06 AM »
I'm no expert by any means, but I have a bit of experience with the OM617.95x (the .950 in my 116, the .952 in my 123, and a little work on my friend's 126 with a .951). BTW, all Mercedes diesels use the letters "OM" ("oelmotor") to distinguish them from the "M" gasoline engines. Also, IIRC the OM617 began being offered in the W116 in 1978, not 1977.

My two M-B's are as follows:
W116.120 - 1979 300SD. Mileage is completely unknown; the speedometer/odometer was replaced at some point in the car's life. The current odometer reads 300,000 miles, but I think the car's closer to 200K. I've only had this car for three months and less than 1500 miles, so I'm still getting to know it.
W123.133 - 1985 300D (federal emissions, so it lacks the "particulate trap" that California models were equipped with). Mileage is now at 283,000 miles, on an original and un-rebuilt drivetrain. Other than a few minor changes (notably the lack of an EGR valve on the W116's engine), the engines in the 116 and the 123 are identical. Nearly all of my "review" is based on my experience with the engine in my 123, but this essentially applies to the 116 and 126 diesels as well.

I would say that the 617 is not a race-winner in stock form. However, I wouldn't call it a slowpoke either. If you know how to drive it (i.e. realizing that all of its power is in the higher RPM range and that flooring the pedal is what the engine wants you to do), you can get reasonable performance out of it...not breakneck by any means, but you won't hold up traffic either. I believe an article reviewing the OM617 turbo stated that its 0-60 mph (or 1-100 kph) time was 20 seconds. The occasional Italian tune-up does wonders for clearing soot out of the muffler ;D More importantly, a properly maintained OM617 will do well on fuel. I haven't driven my 116 enough to get proper fuel economy numbers, but my 123 averages 25 miles per U.S. gallon. I have never gotten below 24 mpg unless there was a problem (once when I had fuel leaks, and another time when my a/c compressor was going out), and on a straight freeway run, I can get 30 mpg out of her. I'm hoping for similar numbers out of the 116. IIRC gasoline M-B's generally get in the high teens for fuel economy, but I can't speak with any authority.

Mechanically, the OM617 is a marvel! It would not be unwarranted to refer to the engine as being rock-solid reliable. I have had my 123 for 60K miles (purchased at 223K miles, and it's at 283K now), and the car has never left me on the side of the road (which is far better than I can say for any vehicle I've owned prior, and I've also owned the 123 for almost double the mileage of any vehicle I'd owned previously). In fact, the only engine work I've done other than routine maintenance is a thermostat replacement. I also opted to flush the cooling system at this time. I have had to do other work on the car, but that was all specific to the W123 chassis, so I imagine it would be of little interest to most people on here. I have found, however, that the car in general and the engine in particular were clearly designed with serviceablilty in mind. Other than a Volkswagen, these two M-B's are the only non-American vehicles I've owned (other vehicles were one Chevy, one International-Harvester, and two Fords {one of which I still own}), and I've found the two M-B's easier to work on BY FAR. The engineers clearly had this in mind when they designed the cars; they appear to have gone out of their way to make things easier to work on. One example is in oil changes, where they made it so you can do it all with one wrench.

As to parts...with the 123, I determined that the "Mercedes parts will break the bank" belief is a myth. Granted, one has to know where to shop (most of my parts purchases have either been from or from, but I've found W123 parts to not be much more expensive than any other vehicle I've owned, and the longevity's worth the extra price. Looking around online, I've found that W116 parts seem to be more costly than W123 parts, but time will tell there.

Unfortunately, I can't compare the 617 to any M-B gasoline engine, since I've never even driven (let alone done any mechanical work on) one.

I hope this helps with the quest some 8)
1979 300SD (W116.120), miles unknown, daily driver, keeping her on the road
1984 Ford F-250 6.9l IH diesel