I really like the style of the early 1970's Mercedes. I'm trying to figure out which ones would be best. When did they come out with the 5 cylibder engine? Is one engine from that era better than the others? I think there weren't any turbos in that era. Does the 300d indicate that it is a 5 cylinder? What typical problems could I expect with cars of this era?

 

the in line 5 was first introduced in 1975 in the 300D on a W115 240D chassis. the chassis only ran for two years 1975 and 1976 in the US it only ran for 1 abroad. in 1977(76 abroad) MB moved to the 123 chassis which they ran until 1985. the styling you are looking for with the single headlights and the inner fog lights only occurs on the 75-76 model years. the turbo was mated to the in line 5 motor on the 1984 300series wagon. the turbo sedans came in 1985.

the good
these vehicles have very few problems to to there robust design and simplicity. the sheet metal is thick the chrome is quality, not 50-60's era Cadillac, but robust none the less. there is no catalytic converter so exhaust repairs are less expensive there are no 02 sensors to deal with. the motor is one of the strongest passenger vehicle motors ever produced. transmissions last just as long with a average like of somewhere around 500k. this is helped by the low output of only 80-88hp.every part you could ever need is still available. from fenders to glass to motor components. some are rather expensive, glass and vacuum pumps, but the suspension and steering systems are rather basic and parts are cheap. hubs are rebuild able unlike modern cars so a spin bearing only costs you the bearings and not the whole spindle assembly. these cars are perhaps the best ever made for conversion to vegetable oil. it can be done cheaply while providing you with independence from most oil and free fuel to boot. Expect 21 to 23 mpg from my personal experence

the unique
80 hp in a 3600 lb car produces a 0-60 time around 23 seconds. it does require an adjustment in your driving style but it lends to developing a very smooth style where momentum preservation becomes standard fair. she will cruise all day at 65-70 with a top speed of somewhere around 85mph, no need to go that fast you want people to enjoy your rolling sculpture don't you? few 70's era 3600 lb car handle as well either. body role is an issue but is not excessive. torsion bars (anti sway) were not added until the mid 80's. the power locks and windows are powered by a vacuum system. it is reliable but leaks do occur and are not as easy to track down as faulty wiring. th dash lights fail due to a corroded rheostat, an easy fix with some electrical contact cleaner and a toothbrush and 11 (inexpensive) bulbs later you are brand new. the climate control system is slightly complex but works well as long as the coolant system gets flushed every few years. owing a diesel in winter needs a few things. a block heater, so if you live an an appt complex you will need to find power. a bottle of diesel 911 to help with winter starting, it really works. and the will to give the glow plugs a moment to warm before you race off to work.

the W115 300D's are classic i am certain if you are slightly mechanically minded you will love the ownership experience.

I love my 76' 460k and that clatter warms even the coldest blood in the morning. i smile every time

 

Thanks OTM, Your input is greatly appreciated. Are you advocating the 5 cylinder over the 4? Do these engines smoke much?

I'm also wondering if a later MB turbo diesel engine would fit into one of these older chassis. I know a purist would never do that. If I did it, I'd keep the old engine in case I wanted to restore it to original at a later date.

Also, I don't know anything about indirect injection. Are there any web pages that explain how it works? Can a low boost turbo be added? EFI?

 

the 5 cylinder is in the 300D the 4 cylinder is in the 240D. have a look at both. the 300D has more power but they have very similar power to weight ratios. Yes it would be very likely that you could swap in a newer turbo motor with a matching transmission. you would be going form a W115 chassis to a W123 so it might not be a direct bolt in. after the 76' MB started to add slightly more complexity, i know for certain that the transmission kick down mechanism is implemented differently.


these motors do smoke, some more than others. i dont get a giant black plume, just a nice dose of light white smoke on a cold morning start. once she is warm she has a similar output to a 3L gasoline engine. I run 20% Biodiesel from my local Meijers and it really helps cut back on the smoke as well as the diesel exhaust smell. the engine also runs much better on Bio than on straight diesel. the idle can be set much lower while running smoother.

i know that a 0-60 time like that sounds wary at first but once you drive one you will understand how fabulous it is. it never has posed an issue for me here in Michigan where individuals often exceed 80 as a highway cruising speed you just have to pay attention when you merge like normal. most people understand your driving a vintage Benz and kindly create some space. often with a thumbs up as they pass.

the fuel injection system is really simple here are a few links that describe the difference
http://en.wikipedia.org/wiki/Indirect_injection
http://autorepair.about.com/cs/gener.../aa102001a.htm

i know a turbo and EFI are very useful technologies but there is almost nothing wrong with the original MB design. a 76' 240D was retired after procuring 4,600,000km as a taxi service.

http://www.worldcarfans.com/classics...ml/country/gcf

you have to drive test drive one to really understand.

 

Kent Bergsma of mercedessource.com says the 115 has a wonderful reputation, The 300D doen't vibrate as badly as the 240D and can keep up on the freeway. But it's hard to find one that's not worn out. Look for water leaks, broken seat padding, Rust in rear quarters, trunk, floors and rockers. Oil and filter changes are messy. Vacuum door lock system not reliable. Heater blower motor can take up to 20 hours to repair. The joke is the 115 assembly started with the blower motor then built the auto around it.
Best years are1974 to 1976 240D with 4 speed manual tranny, and 1975 to 1976 300D with 5 cylinder non-turbo...