Engine Swap
 

I need more power in my 1983 240D. Is there anyone who knows of an inexpensive engine swap I could do? I don't have any preference whether it is diesel or not, but figured it would be cheaper to stick with diesel. I would like to spend less then $5k on it. If it is possible to swap for a gas engine, how much power could I expect to be able to put into it? (560 S class engine? I hope!!!)

Thanks
-Ryan Sturm
(Member since today!!!!!!!)

The 240D is a car that was designed to be a reliable, comfortable and economical form of transportation. They are so solid that they feel like they're cast in one piece. But, they are not by any stretch of the imagination a great handling performance car.

If you want to spend time and money on an engine swap, I totally understand that urge, I've done a few in my life and they were not done out of practicality, but for the challenge of doing them. But, you can find jillions of cars better suited to such reengineering.

To begin with, due to several elements of the engine compartment, such as the steering box and the sway bar along the firewall, this would not be a very easy car to do an engine swap.

Second of all the rear axle and jack shafts were designed to handle no more than a little under 200 horsepower. That's what the six cylinder gas engine used in the 123 developed.

There are a few DOHC gas six cylinder 123's around that would give you a more powerful car if you're stuck on the 123.

My point is that these cars are GREAT for what they were intended, but you can come up with so many OTHER great cars, MB's included, for an engine swap that will give you a much more fun car to drive, probably with less time and money spent on them.

With that said, if you are still bent on this project, look through some old posts here for some information on a 4.X litre Chevy V6 into a 123 wagon. There is much detail offered including some good photographs. The gentlemen that did the swap apparently did an excellent job. I don't know if you have done such work before, if you have, I'm sure you know that you will need several additional skills beyond normal car maintenance and repair, including good welding skills/equipment.

Best of luck and keep us posted on your progress,

I saw an older 300SEL (60's) with what looked like a chevy small block in it... the only problem i have with that is I would lose the whole fact of reliability in the car... as you can surely tell me, 240's are mileage cars, as yours has 533k miles on it. I would love to fit it with a 280E engine, but with little experience, i dont know all I would need to change. I would love to put a 200hp engine in it, but the weight of the car would probably kill the "speedy" aspect of that.... anyway i am about to look for the old postings and will keep up with questions.... Thanks for the quick reply

The 123 is a very light car. It weighs little, if any, more than a Camaro.

When you swap ANY engine into the car, MB or otherwise, the statistical reliability is going to suffer from the engine change. Engine swaps involve adapting this and fabricating that with only one chance to test and engineer that piece correctly. With production automobiles, every piece is tested and worked out before the car is put in production. You can bet that there were problems of some sort with the prototype. Any engine swap must be considered as the prototype. The only way you can maintain good statistical reliability is leave the car as engineered and built.

Best of luck,

diesel swap
 

Correct me if I'm wrong but I would imagine a diesel swap would
be just about one of the hardest things to do, you would have to change out the fuel system and add an ignition system. Speaking of the small block chevy swap, my friend did one on a volvo 240, the car had 500hp, but he had a full garage and machine shop on his hands, and it still took him nearly a year.

83 240D,

Tell us something about the car if it is for sale ...

George

Here is my "standard" text:

1983 Mercedes Benz 240D
-190,225 Miles
-Silver Exterior, Blue Leather Interior
-Automatic
-Air Conditioning
-Sunroof
-Power Windows
-Power Door Locks
-Cruise Control
-Cassette Player
-CD Player
-4 Cylinder Diesel
-$7,500 OBO
Ryan Sturm
Baltimore, MD area
E-mail prsbirds@home.com
Cell 443-562-2551
Leave Message

Ryan,

You can get an entire car with a more powerful engine for the $5K you're willing to spend on a swap. Try an 81-85 300SD for size if you want to stick with a Diesel. An 82-85 300D will have the same turbodiesel engine as the 300SD in the same body as your 240D.

If your 240D is so well kept that it warrants $7500, you might be a little disappointed with the 300s you can get for $5000. They'll be excellent commuters, but they will have signs of being almost 20 years old.

Sixto
91 300SE
81 300SD

4.3 Liter V6 swap into 123...
 

Hi there,
I'm the guy that did the 4.3L swap into my 123 chassis. (1982 300D) It took me about two months of evenings and weekends to perform the swap, as I wanted to end up with a clean installation, and it cost just under $1K... However, I shopped for bargains and got lucky by acquiring a 1992 Astrovan engine for only $125, including the engine wiring harness and computer. The T700R4 transmission was $450, and the fuel pump was over $75. I didn't have to do any cutting of the chassis, but used a 10 ton hydraulic jack to spread the tunnel by about 2 1/2 inches to give the transmission room to reside in. It took some time to fabricate the motor mount brackets and exhaust. I have put about 8K miles on the finished product now, with no problems of any kind. It gets about 21 mpg around town, go to work driving. On the highway it will give around 28 mpg, cruising at 80mph with the air conditioning on and with 4 people in the car. It has much more performance than the diesel, is much quieter, more fun to drive, and I believe it will be more reliable and less costly to own than the diesel engine was - the 4.3L V6 was used in pickup trucks and vans, and is a very reliable engine, having been derived from the 350 ci chevrolet engine. (The 4.3L V6 is just a 350 with 2 cylinders cut off to make a V6) With the overdrive transmission and lockup torque converter, the car is able to cruise at high speeds with low engine rpms. You can view my web page on the car at: http://pages.prodigy.net/rwooldridge/mercedes.htm

Feel free to ask questions!

Richard Wooldridge, retired IBM Field Engineer
'82 300D/4.3L V6
'85 GMC S15 pickup
'89 Astrovan
'94 Ford Taurus
'77 XJ6L Jag
'77 280Z 2+2
'69 Clark Cortez motorhome with Olds 455 Toronado conversion
There are more, but space prohibits....

VERY cool... yes that is definately the car I saw, but i dont know where because it wasnt your page (i dont think). Thanks so much for that, you did a beautiful job with it... i am very impressed. It also looks very similar to the original diesel powerplant, so the originality is not totally lost. Just the agonizingly slow accelleration... but im sure you wont miss that....

If you would like a more conservative conversion, I have a 1983 300SD engine and trans (still in car) that we rebuilt 3 years ago. Both were totally rebuilt the engine getting bored with new pistons. (Total cost in rural Gainesville was near 7k). I'd sell both for $3k. (I'd throw in the car [bg])

Changing to a 300D is almost a no-brainer, just need to change the engine, rad, location of tranny mount and driveshaft (if it is similar to the 115s). Motor mounts are the same, and in the same place, wiring is the same, so are injection pump connections, etc.

Anything else could be a huge pain.

And any motor derived from a Chevy 350 will not last anything like any engine from MB -- the Chevy smallblock was (as is) a cheap engine made understrengh, designed in 1953 -- very short piston skirts, undersized crank (also usually off and crooked), very light weight and thin cylider walls, tiny bearings, etc. Good for one rebuild at 100,000 miles and then junk unless you spend a fortune remanufacturing it or get lucky and get a non-defective one from the factory. Some will run forever (my work van has 282,000 on it!), but most will throw a rod somewhere in the vicinity of 130,000.

Horsepower output for displacement is very small, and if you crank up the very low horsepower, it goes faster, even the 4-bolt main truck engines.

I'd go for a 300E motor if I was going to put a gas engine it in -- the electronics are fairly simple.

Otherwise, if you want a sports car, buy one -- you are never going to get that 240 to drive like a BMW 318i, anyway! Save the 240 for what it does best -- good reliable inexpensive daily transportation, and buy a sports car for blasting down twisty roads and stoplight drags.

Peter

haha... thanks... actually its funny that you mention that because i found a (potential) buyer for the benz and it is going to be left at my mechanics tonight to have him check it out and make it completely "sellable". I am thinking about moving to an Audi A4 1.8T quattro, with a stick (for extra fun) or a tiptronic. If I can sell the benz, i think this is the best choice for me... according to where I am going to be living next year for college, but the benz is a car I have loved since before I was born, and my first ride in it was my first day alive, so I cannot complain about that. However with the changing times, the benz is just too slow, and too bad in the snow for my needs. If the buyer backs down and doesnt want it, I will definately consider a 300E engine in it, though. THanks for the reply.

Yeah, I was quite surprised by the horrible traction problems with both my diesels the first year I had them -- the Volvo will easily spin the tires even on wet roads, let alone ice or snow. I've gotten it stuck several times, once nearly dropped it off the side of a steep hill into a forest when someone convinced me to try one more time!

Peter

Hey guys, I am surprised to hear you have difficulty in snow with the W123 Diesels. I have driven my 1971 (W115) 220D and 1975 (W115) and 1982 240D's all over the Northeast, and up to Alaska and back. I also ski with my family quite a bit, and have never had anything but great experiences in snow and ice with these cars.

They all had/have manual transmissions, which may have something to do with the results I have had, and I always use 4 season Michelin "H" rated tires (195/70HR-14 MXV's presently and for the last 6 years or more) which may also help. But I can say I have never been stuck so I could not get out, and I have passed or crawled around other cars in snow and ice storms that have closed roads.

I did learn in Alaska that you put the clutch in before you lift the accelerator, as the rear wheels will lose traction and run at idle speed almost instantly in really icy conditions going downhill due to the compression braking of the engine. The effect is a lot like applying the emergency brake, and the rear end will quickly pass the front end. Other than that, I have only great things to say about the car in snow or ice, or rain or any combination of them.

Jim

Mssg to PSFred...
 

Hi there,
I don't have any particular allegiance to GM, but I think your commentary and opinions of the chevy small block neglect the facts. The 300D has a main bearing diameter of 2.798". The Chevy 4.3 has a main bearing diameter of 2.45", or roughly .35" smaller, but the shaft is only half as long, and the combustion forces are striking the shaft from two directions 90 degrees apart, so it has much less need of large main bearings. The 300D rod bearings are a very small 2.078" in diameter! The Chevy rod bearings are 2.5" in diameter, almost a full 1/2" larger!! You refer to the skimpy skirt of the chevy piston - have you ever seen one that showed any wear, if the engine was taken care of? I haven't seen any with significant wear! The rings on both engines seem to last about the same. The Chevy has a roller cam, the 300D does not. The Chevy has stronger cam drive gears and chain. I know the 300D is a terrific engine, but it is not without its problems, and I truly believe that the chevy engine, at 1/4 the price out of the box, is a better value. The Mercedes body, on the other hand, is a piece of quality craftsmanship that isn't equalled by anything produced in the USA... Solid, rattlefree, and comfortable. Please understand by my comments that I'm not trying to argue with you, just wish to make some positive comments towards the 4.3L engine. By the way, the 4.3L engine can produce 200hp (net) in the vortec version and 260 ft/lbs of torque, while the 300D turbo engine produces only 120hp (net) and 170 ft/lbs of torque. I know that all you diesel fans out there are going to say that diesel power is "different", but it really isn't. The torque is what moves the car, and 260 ft/lbs of torque moves a car a lot better than 170 ft/lbs, as I can personally verify.
The Chevy small-block was first designed in 1953, but has undergone continuous refinement ever since, resulting in a truly fine piece of engineering currently. The Mercedes 300D didn't make an appearance until 1981, but the basic engine designs are older than the chevy. The fact that it has been around as long as it has is a tribute to it's durability, and the same goes for the chevy. I am well aware that GM has loosed some designs upon the motoring world that were not quite ready for home use - for instance the infamous Vega aluminum engine, the Cadillac 4.5L that was famous for spinning bearings, and most all their diesel attempts. But the 4.3 is an excellent product.
Hope I haven't offended anyone with my ramblings!
Richard Wooldridge

Richard:

The Vortec is a new design, not the old 350.

All of the newer engines are a vast improvement on the old, mainly because GM discovered the idea that all the parts should be the same size, not just fit the the holes with lots of slop!

If you look at a 350 crank next to an MB crank, you will know immediately why the MB lasts longer. It weighs twice as much, for starters.

The 300D was first sold in 1975 (my brother has one, SN <29,000). It was the four cylinder block with a fifth cylinder added -- literally. Original design dates from pre-Hitler, had overhead cam in the late 1930's. MB also made countershaft crown gear drive valve trains, clutched blowers (half way down the synchro clutch engaged the Roots blower), etc.

GM just shoves any old crap out the door, in general.

Torque is the key to acceleration -- what makes our old diesels driveable is that the torque curve matchs actual driving pretty well -- usually peaks at 2400 rpm or so. Lots of fun to get the old Volvo wound up and let her rip -- the slow start confuses gasmobile drivers, and I run away from them as the old girl shifts up and takes off.

And diesels with auto trans a lousy in snow -- way, way too much torque. My Volvo is even a pain on wet pavement -- very easy to spin the tires (both of them, without positrack!). Horrible on ice or snow -- the turbo comes up and the wheels spin like crazy. I expect the 300D to be worse -- more torque.

I suspect a manual tranny would be much better -- more control over what the engine is doing.

Peter

I agree with Richards's comments about the Chevy 4.3L engine. I have owned my Chevy Astro since new (150HP non vortec version) and the only engine related problems was that I replaced the o-rings for the injectors. I belive that the fuel injector cleaner I used ate away at the original o-rings. The only other minor problem is that my rear transmission seal is starting to leak.

My only complant with this engine is that the valve seals tend to leak which causes a puff of smoke when starting the engine. Since access to the valve seals is very difficult on a Astro van I just live with it.

I do firmly belive that the quality of an engine is directly related on how well it has been maintained.

Ray:

We've had several Astro vans at work -- they all threw a rod before 200,000 miles.

O-rings die of old age -- it wasn't anything you put in the gasoline. They need to be replaced every six years or so, along with any and all vacuum lines.

My old (92) current work van has 282,000 miles on it, but we change oil every 3000 miles or less, and use good oil. These are usually driven several hundred miles a day, seven days a week, too. This is fairly unusual for a GM -- they usually crap out about 150,000.

If you are burning oil, I would definitely recommend valve seal replacements however much of a pain it is. The oil ash eats rings and cylinder walls. The drawback is that you will find that the valve guides are worn out and the valve springs shot, and will need to do an overhaul. When the heads are off, you will also find the cylinder walls shot, the pistons bad, etc, etc. Bearings are already marginal, as they aren't up to snuff from the factory.

Listen carefully -- if you start to hear "diesel" sounds from the engine at low speeds, you have a rod bearing knocking and the rod will be out the side of the block shortly!

If you have oil in the air cleaner from the crankcase ventilation, get rid of the motor -- they go fast once the blowby is too much for the PCV system.

I'm still not impressed with the new GM engines -- a decent MB will still have good valve seals at that age and milage, or a Volvo -- had to put a head on my sisters 740 turbo this summer because she blew the upper radiator hose nipple off the radiator on the interstate -- fried the head. Bottom half nearly new, the only other problem was a leak at the distributor seals with 160,000 miles on it.

Oh well, maybe I'm wrong, but I will stick with MB for the forseeable future!

Peter

More comments....
 

Hi again,
I should have specified "300D TURBO" in my previous post - I was referring to the turbocharged diesel as being introduced in 1981, as that's the engine I used for horsepower and torque comparisons. Sorry to have missed doing that!
PSFred, the Vortec engine is derived from the 350 - the rods are the same part number, as are the main and rod bearings. I agree that it is a considerably re-engineered engine as regards oil sealing, intake manifold sophistication, computer controls, etc. But the basic block and head designs still retain their 350 heritage.
After reading the various comments regarding poor performance in the snow, I went out and looked at my old 300D engine, and sure enough, the engine is actually sitting slightly ahead of the front axle in the 123 chassis. This makes for a poor front/rear weight distribution in the car, which I'm sure accounts for most of the problems in the snow. I didn't experience any problems with my setup, but the engine is mostly behind the axle, and probably has close to 50-50 weight distribution, plus it's lighter on the front than the diesel powered car. I don't buy the "too much torque" idea that psfred has, because my car has MUCH more torque, and also has lower gearing in first gear, and is quite controllable. I do know that our '74 280C had the same problems in snow that others mentioned, and it also has the same weight distribution problem - the long 6 cyl inline gas engine hangs out too far in the front.
Once again, I'm hoping for constructive discussion, not just slamming for the sake of slamming...

Regards,
Richard Wooldridge

Peter,

Thanks for sharing you experience with high milage Astro vans. I will keep my eyes and ears alert for early signs of failure. Since my Astro van is not driven much, it might be a awhile before I hit the 200,000 mark.

I did experience the bent rod (it didn't go through the cast iron block) and blowby with my 79 Toronado (350 Olds engine) at about 150,000. Since I was not the original owner of the Toronado there was a good amount of sludge build up under the valve covers.

I had the valve covers partially of on my Astro about 6 months ago and as with my Honda (owned since new) it was so clean that you could eat off of it.

Both my Astro and Honda has had 2,000 mi oil changes for the first 100,000 mi, then I extended the oil changes to 3,000 mi. Since my Astro has not been driven much lately I switched to Mobil 1 oil.

I am not implying that my Astro will be trouble free forever, but I am attempting to give it a healthy start.