1980 M116 300SD

    What should I be looking for in buying a 1980 M116 300SD?
    What problems are prevalent in this model?
    How much does it cost to fix them?
    I try to work on cars myself.
    I have a 1979 MB 240d and have been driving it for the last year.
    Jerry
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There is a 116 group on Yahoo, you might sign up for that and post there, they are helpful.
said:

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Fred Emmerich
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fred snipped-for-privacy@comcast.net wrote in message

By far the biggest headache is the automatic climate control system. Failures of either the amplifier or the servo are common. Either can be easily replaced, the AMP goes for about $120, the servo $600. The servo most commonly fails by developing a coolant leak, which isn't a good thing in a unit with 4 cooling hoses, about 10 vacuum lines, and about another 10 electrical connections all hooked to it. If you do need to replace the servo, Performance Analysisn in Tenn. sells remanufactured ones that replace the lower crack prone plastic housing with an aluminum one. And if it fails, they will fix it for $100 for life.
Check cars you are looking at by cycling the climate control from full heat to full cooling and make sure everything is working. IT is also a good idea to do this periodically about once a month, as this runs the motor, mechanism, feedback potentiometer, etc in the servo through it's full range.
The servo is under the hood, near the firewall, passenger side. Make sure there is no sign of coolant leaking.
Other things to look for are rust, which could be a big problem depending on where the car was driven. Pull the floor mats, front and rear and inspect for rust there. I just pulled some parts from one headed to the junk heap, and in front there was no floor left, you could see the road. I suspect this one rusted from the inside out, as that area is common for water pooling from blocked AC drains, window leaks, etc. And check the vacuum system which works the door locks, trunk lock, fuel lock, etc. to make sure it works. The system is complex and can develop leaks.
If you get one in good condition, these are tough strong cars, some would say among the best MB has made. I had an accident recently, where I hit a 3 year old chevrolet. I barely felt the collision, the Chevy was totalled, I drove the 300SD home.
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I've owned one of these since it was new. The engine is solid, also the transmission. The engine is simple and easily maintained by a DIY owner. The 1980 model has an aluminum hood, trunk lid and firewall to reduce weight and the engine's cam was modified to make 120 HP vs. 110 HP in prior years. I averaged 24 mpg in commute driving and about 26 mpg on trips.
This car's flaw is its complicated climate control system which is fine when all is in order. The problem for a buyer of such a 24 year old car is that someone has tried to fix it and has messed it up. The CC system has an "amplifier" (logic board) and a "servo," that monster in the right rear engine bay. Both these parts break and both can be bought as rebuilt parts so don't even think of calling the dealer about them. In my experience most problems are from one or the other of these parts.
I've had two other problems: the aluminum window guide on the passenger's front door bent and the regulator failed. The engine air cleaner's support bracket breaks from metal fatigue - I had the last new one reinforced by a welder before I installed it.
The 116 has a reputation for rust but my car has none as it's never driven in snow or salted roads.
The 116 turbodiesel is a fine car, I hope you can find one in good condition.
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I aquired a 1980 300SD about three months ago and from several web sites, I find that they ALL have the same common problems.
1. The "servo" in the Climate Control system had failed three previous times in my car. About $500 for a rebuilt unit. Living in Florida, I have bypassed the automatic features of the servo and now have just two levels of airconditioning. From the junkyard, I have aquired three more servos for about $15 each and am in the process of making two useable units from the four that I have. MB purchased this CC system from Chrysler where it was used in the early "70s Imperial.
2. The Cruise Control suffered the same failure mode as every other 116, solder joints. I replaced the amplifier with one from the junkyard, it works sometimes.
3. Engine and transmission mounts were in real bad shape, replaced them myself for about $65.
4. The air cleaner mounting bracket breaks on them all. I picked up one at the junkyard and even it had broken (same place) and had been welded. I had mine welded, so I now have a spare. One of the three rubber shock mounts had to be replaced, $3.
5. And of course, the horsehair padding in the door panels had long ago turned to powder. Replacement with new foam rubber was only about $25, but labor intensive. Be careful removing the interrior door panels, they lift up and off, not like others that are pryed off.
The following web site has the maintenence and service manual on-line.
http://217.120.8.22/mercedesw116/W116cdrom/program/matrix6.htm
Good luck! I got a good one!
Bob Moore Tarpon Springs, FL
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