Just how slow should a automatic 240D be?
 

Hi Folks,

I really don't mind driving a slow car, in fact I prefer it because I believe it forces me to be a better driver.

Just curious though.. How slow are most of your 240D automatics?

For example,

Climbing a steep incline in 3rd gear at 30mph I can put the pedal to the floor and
the car with slow down to about 25 or if I press the kick down switch it will downshift to second and then climb the hill at full throttle.

I'm finding myself using full throttle a lot lately, especially climbing hills.

My car is in good running order with new filters, freshly rebuilt injectors, and a properly tuned transmission.

I adjusted the valves roughly 5k miles ago.

I believe its driving normal for a 67hp 3,500 lb car.

I bought a new 240D-4 speed in 1983. Living in So California with a lot of freeways, I sold the car after 1 year as the car was dangerous getting on the freeway due to slow acceleration. The auto trans really adds to the problem. My next Mercedes was a new 1985 300D. The extra cylinder and turbocharger made a world of difference.

Having owned an NA 300d at a mile high and at the foot of the Rockies, I can say it is very slow and I had an extra cylinder. A 240d would result in a long slow drive to the top of the divide. Maybe 25mph at the tunnel?

I have a 78 300D and for around town driving, and even highway driving it's fine. Slow yes, but very easy to hustle with normal traffic.

Having read how slow and dangerous they can be, due to the lack of power I thought people were stretching it.....

I took my 300D to the mountains today... Wow! Wot on some hills and it would start to slow down until it would kick down. I couldn't imagine a 240D!

I think you Americans are too used to big V8s. Hell, in a '77 80hp auto 300D I beat a 2.4 Toyota ute at a set of lights.

If my math is correct, at 10,000 ft, without a turbo, that 80hp becomes 56hp not a hell of a lot of ponies to climb a steep hill. Where I live, I'm not going west without climbing to at least 10000 ft.

Well that's not the car's fault lol :)

Other drivers were the concern before I swapped the 617 turbo into my 240D. My car is a 4speed.

Once up to speed there's not much of an issue, but my foot was always to the floor when accelerating. I don't recall around town driving to be of any problem.

Other drivers are oblivious to the concept of maintaining a constant speed. On the highway you prepare for a hill by accelerating at the base and keeping RPMs up so you can maintain speed up the hill. Other drivers will slow down 15-20mph forcing you to match their speed, then accelerate away leaving you stuck 20mph below the speed limit for the duration of the hill climb.

Passing on the highway requires quite a bit of time. If you're stuck behind a slow driver its nearly impossible to merge into the passing lane and match the speed of other traffic which is passing.

Most highway passing goes like this: All traffic is clear and you merge out to pass > other driver speeds up 5-10 mph > you can't out accelerate and merge back over > other driver slows back down.

Driving a 240 automatic is the automotive equivilant of trying to get around a 400lb person with a leg cast in a supermarket aisle. You just arent going anywhere quick.

A 4 speed swap will dramatically improve the usability of your 240.

The lack of highway merging/passing and lack of hill climbing ability put me off anything less than a turbo 300D/TD. I had 2 friends in high school with diesel Benzes, one with a 240D auto, the other with a 300D stick N/A. The 300D was capable of merging, but it wasn't fast, and neither did well on the hills around here. When the speed limit on the interstate is 80, but your car is only doing 40 at WOT up the hill, you become a danger not only to yourself, but all the cars, Semis, busses, and bikes blowing past you at 90+ SCARY SCARY SCARY.

If you live in a flat area, the N/A engines fine, but if you have hills, a turbo is needed!

From my limited experience many times there are simple things typically wrong that further reduce power in 240ds.


The linkage from the pedal to the injection pump is not providing full movement. This is too typical not to examine.


The fuel system is not providing the right pressure in the base of the injection pump is another. Both are pretty easy to check and rectify if needed. Also since many of these cars sat around a lot. Make sure all the brake calipers are free and not dragging.


I have stated before that the 240ds do not have an abundance of power to start with. So you have to verify that what power is possible is still available.


You have a few other aging things to consider as well. For example are the shift points in the transmission coming on too early? Is the engine worn down with time and use too much? Anyways the average 0-60 acceleration time is known for your car in the archives. How does yours do in comparison?

It is a pretty safe bet that if I purchased six of them. Three would not do the average time until I repaired a few reasonably simple things.

I've driven several NA diesels, including a 300D, and it takes a bit of learning to find the sweet spot for power. Unlike a gasser, stomped to the floor doesn't get it. Try approaching hills at a little less than full throttle and you will find what rpm range works better.

One other factor to consider is the AC pump. When I turned on the AC in our 77 300dNA, power was considerably reduced.

The 240d is slow vehicle but even slower when its not getting full throttle due worn regulating linkage and bushings. You need to have someone get in the car and push the accellerator pedal down to the kickdown switch while you look at the side of the injection pump to see if the lever is hitting the stop screw. If it is getting full throttle then you should verify that the engine is reaching maximum rated RPMs while driving under full load. If you are getting full throttle at the injection pump but not reaching max rpm, then you may have a fuel delivery problem such as a dirty fuel strainer in the tank, or fuel filters restricted. Ive seen something as simple as a floor mat sliding under the gas pedal cause these cars to fail to reach full throttle and consequently cut power in half!