5 cyl vs. 6 cyl diesel
 

I'm not new to diesels, but I am new to Mercedes diesels. I had a VW diesel for years but I'm moving up to the major leagues. I'm trying to determine whether I want to go with an '81-'85 5 cyl 300 or a post '85 6 cyl 300 model. Both seem to show significant longevity, and it may be very subjective but which is better? What is a reasonble expectation of mileage for the 5 cylinder vs. 6 cylinder? How much does the turbo add mileage wise. These are very basic questions for such a learned group, but I can't think of a better group to ask. Thanks for everyone's help. I live in Virginia and I am currently looking. Actually I am currently waiting for the current tornado warning to pass thanks to the remnants of Tropical Storm Cindy. Need to sign off before I get the inevitable call to go to work.

the five
 

is generaly agreed to be about bullletproof as an engine.

the sixes from 86 to mid ninties or so have some issues that can be pretty bad, but when running good are really nice driving cars. also the older cars ac is marginal. otherwise the cars are very similar if you are looking at s classes. they all are 126 bodies. in 86 or so the e class came out. the e class motors are five cylinders or sixes. the fives are pretty bulletproof here too. the e classes are generally not as mechanic friendly as the 123 bodies and 126 bodies.

The OM601 (4cyl), OM602 (5cyl) and OM603 (6cyl) engines will be the most familiar to you if you're used to VW diesels (cast iron block/aluminum head w/lifter buckets). IMHO, the OM602 as found in the '87 190D 2.5turbo (very rare) and '90-'93 300D 2.5 will return the highest level of fuel economy, performance and reliability of any diesel engine North American MB offered to date. In addition, the chassis these engines are found in are far superior to the older model Benzes. For example, I own an older W123 chassis w/OM617 (cast iron block/head) that I rely upon for running errands, must-make-it-there trips, and backup, but my true love and object of my affection is a S124 chassis w/OM603 (6 cyl) for it's heavenly ride, handling, comfort, performance and fuel economy--there really is no direct comparison.

The 5 cylinder (617) is louder, durable, and seems like something of a throw back. It's hard to hurt unless something silly happens to it. Just a very solid motor... simple to work on. The 6 cylinder (603) is a bit more complex but not much, no need to be scared.



The 6 seems more refined, I supposed due to the firing order. It's much quieter and idles differently. I haven't had a chance to really drive mine much as I've owned it a week and have been out gathering parts in my off time. My tie rods are bent so it only goes about 30mph lol

603 motor does crack heads if over heated, it happens but you just have to keep the eye on the vital signs. Something you should do anyway. I'm very pleased with this vehicle so far, seems like it will be load of fun.



The 603 is what 143hp vs 120hp and I believe torque went up from 170tq to 195tq also, so it should run a bit better too.

It is easily summarized. The later six is indeed more refined and is superior WHEN EVERYTHING IS RIGHT WITH IT. Given the iron head of the earlier four or five cylinder, it is more trouble free.

Good luck,

How about coming at it from another angle? Decide whether you want a W123, W126 or W124 then learn to live with the engine that comes with it.

Sixto
95 S420
87 300SDL

Depending on the year and model

W126
5-cylinder OM617 300SD
6-cylinder OM603 300SDL

W124
5-cylinder OM602, E300D 2.5L
6-cylinder OM603, E300D, 1987 only
6-cylinder OM606, E300D.

W210
6-cylinder OM606...

Isn't this fun? ;)

Wait, it even gets better.......the 1987 300D, is the fastest of the whole lot. Imported by MB only one year to the US, the 87 [U]was the fastest production diesel automobile in the world...WOW.....and still get 30 mpg.

Todays MB diesels are even faster, but $$,$$$ :eek:

Thanks for everyone's help, I've got something to work with. Now comes the waiting game to find a good one.

What body was the 1987 300D?

My answer is that the 606 is the sweetist diesel MB has brought to this country. 4 valves per cylinder with double overhead cams, it will rev sky high and pull like crazy in turbo form. They are also extremly durable and seem to return extremly good mileage. I think as the years roll on 606's will prove to be very very long lived. I have seen some nice tight examples with 300k+ on them.

The 603 comes in a close second for me. They are extremly durable and are fun to drive as well. The 603 has a very nice sound at full throttle and returns good mpgs.

Both of the above engines have no problem in the winter.

Now the older 617 is a good engine, but it is not as powerful or returns as good mpg's as the newer motors. Also dare I say this they don't seem to last as long and hold up as well.

W124 just like the ubiquitous 300E.

Sixto
95 S420
87 300SDL

Bite your tongue, HG, eBay is full of 617s with 500K - million mile potential :)

Sixto
95 S420
87 300SDL

What about the 602 compared to the 603 or 606?

I have never driven or worked on a 602, but they seem to be good engines. I almost bought a 1992 300D when I was hunting for a MB. It had 290k on it and was in very, very good shape. If the guy wasn't asking to much money for it I would have bought it.

The diesel guys don't want to hear this, but you can buy a 300E for ~60% of the cost of the diesel (in a 124 car), and its smoother, faster and parts are cheaper (and easier to find used.) You lose 8mpg. Maintenance is probably a toss up. The diesels are MUCH more expensive in the 124 body. Check out autotrader.com. You will pay a few thousand dollars (at least!) to gain 10mpg at the pump.

I'm a diesel lover too (my 300D is my second in 9 years), but after 1985, the gas v. diesel debate gets complicated.

Like sixto said, decide what chassis you want, then pick a drivetrain. It probably snows where you are, so rustability becomes an issue too.

I suggest you spend a week or so (there is that much information on this site in the archives) and get a feel for the strenghts and weaknesses of each model.

Might want to check out what 'wolf walker' has to say about MB diesels. I think he came over from VW diesels.

I've been on autotrader a lot lately and I did notice the price difference between comparable W124 300E and 300D.

I keep going back and forth between the W123 and the W124 style. I can't decide ...

300SD is a W116 (78-80) or a W126 (81-85)

Get a Diesel Vanagon to keep the 65 bus company :)

Sixto
95 S420
87 300SDL

No, that would be cheating on the '65. When I get a Mercedes that's branching out :)

i guess its just a natural progression to go from air cooled flat 4s to the benz diesel, if you leaf through the idiot guide, there are many old mercs in there(love that guys work!) both writing and art are great(yeah, i know, its two different guys..)

also-- for you diesel people, pick up this book-- john muir's idiot guide for vws its a hell of a read. taught me how an internal combustion engine works=)

ive got a little red 65 1200 sedan. good little car, about a bazillion miles, came with *plaid* seat covers! its being restored and cant be driven :( but i guess thats good, ive always wanted a pristine beetle. one with a white interior (waiting to be put in.. ivory vinyl with camel tweedinserts / tan carpets) itll be wonderful when its done and...dare i say it? ...faster than the mercedes :P

I'd like to find a clean low mileage Diesel Vanagon, I've seen one and sorta like it OTOH the stall is pretty full now besides my wife might put me out of the house if I bring home another vehicle!
Another soulution for m.skeen is to buy one of each!

1971 220 (gas) 4-spd manual 106441*
1979 300TD w/ ’85 turbo engine 298446
1983 300D 244626
1985 300TD 226868
1987 300D #1 262300
1987 300D #2 project car WIP
* not sure if its once over on the odometer or twice around!

Anyone try running the newer MB diesels on WVO?

When I started talking about getting a Merecedes my wife rolled her eyes. She does put up with all of my car talk and even helps me out when I'm working on our cars so I can't complain. At least she didn't tell me I had to sell the bus to get diesel! :eek:

Not sure about 'later' but once in a while I run the SDL on almost straight new VO with no ill effect. I don't do it often enough to comment on long-term effects.

Sixto
95 S420
87 300SDL

I meant the ones we were discussing in this thread, your SDL would be one of them.

I think this is sorta contradictory...more parts generally = more stuff to need maintenence (therefore) equal maintence between the two = one fails first :)

The 617 stands up pretty well...you don't often find examples of people abandoning their 617 when it "clunks out", the "head cracks, or it "won't start"

Just like the older 220D's, 240D's, etc. the simpler engine takes less to get more as far as longevitiy.

You can drive a 617 with loads of blowby and numerous problems until the day it dies whereas the 6 cylinders are a tad more finnikey about all their trinkets working in sync.

But the 6 is fast...what can I say :D

You know, it really doesn't matter which motor you buy. they are all old cars and the possibility of getting burned is always there.

Just buy the nicest, best condition MB you can find with a color you like. NO matter what you buy, you're going to want another model within a year or two, GARUNTEED.

E class, S Class, diesel or gas, they're all a pain in the ass.

Time to go fix broken window regulator #8 in 10 years! Then tighten a belt, track down a vacuum leak and the list goes on. Always.

fahrgewehr2 I am glad I didn't buy a 560SEL at todays fuel prices. A 560 would probably get low teens 15mpg if I'm lucky. My SDL is good for 10mpg more. Maintaince is probably a wash.

Now if you compare say a W210 E320 to an E300D well then that gets tricky.

It doesn't really matter what anyone else says buy whatever you like. Their really is no bad MB or bad engine.

Only bad evaporators, heads and con rods? :D

Seriously, get what fits you. The rest you'll learn to live with. Or did I say that already?

Sixto
95 S420
87 300SDL

A 560SEL is not for everyone. Its a GREAT car, powerful and fast. I am not complaining about fuel prices... if one can't afford something so simple as fuel, then driving is not for them. While I was abroad, fuel prices were nearly double of what I am paying here. We're getting a deal since our taxes are not as high.

ps - 15 mpg is what you would expect for stop and go, high traffic city driving. On the open roads, it gets close to 20 mpg.

Snibble I will run 400 miles a week on my car during the school year. I don't want to buy that much fuel, I'd rather spend my money on other things.

Assuming I would get 15mpg out of a 560SEL thats like $70 a week; vs $40-$45 for my SDL. I do mostly stop and go and city driving.

If you drive a lot fuel costs add up over the course of a year.

$30 a week over the course of a year is $1560. I could buy myself a very nice fly rod or new pair of ski's everyear with those savings. :D

If I drove like 100 miles a week I wouldn't give a crap about fuel mileage or cost.

I would wager that there are very few mb diesel-heads who would claim that the 6 is more long lived than the 617; aluminum vs iron, duel overhead vs single overhead cam (higher revs vs lower revs). I remember a discussion on another board that made a lot of sense. The basic idea was that the diesel 6's were engineered from start to finish to be placed in luxury s-class vehicles. The diesel 5's were engineered from start to finish to be placed in workhorse vehicles (trucks-taxi's-limos) and industrial machinery. Consumer grade longevity vs industrial grade longevity.

Brrrrr
 

Cold weather starting ability for people who live in a northern climate could be an easy demarcation line between the 617 and the 603/606 engines.

When I lived in Portland Maine, my 1984 300D would not start if the temp fell below 15 degrees fahrenheit unless the block heater had been plugged in the night before. And this is with a new battery and starter motor.

I do not know how the six cylinder cars would do in the cold, but if they will start in the winter with-out plugging them then that could play into the decision process for those who live in the north.

I've had one 617 in the family and a 601 as well as a 603. The 60x engines start better in the cold. They seem to take a little longer to warm up to if if you know what I mean. Once the 617 is running, if you get it running, the engiens smoothes out faster. The 603 will skip for a minute or two. Also, you will see more higher mileage 603 engined cars for sale than 617's, look for yourself. I've personally looked at buying two different SDL's before I bought mine and each had between 450-465k miles. A 617 doesn't hold any compression that long.

The 617's are generally harder to break, (harder to over-heat, etc.), but they also tend to wear out faster.

Thanks
David

I found 17 sdl's and 19 sd's on cars.com. Just from this it does indeed appear that the sdl's are lasting longer. Interesting...

Note; I deleted the listings that did not include odometer mileage.

SDL

1987 Mercedes-Benz S-Class 300SDL $6,856 236,553 The Toy Store Sedan Blue
1987 Mercedes-Benz S-Class 300SDL $6,250 159,000 Dealer Sedan Gray
1986 Mercedes-Benz S-Class 300SDL $5,700 139,950 Individual Seller Sedan Charcoal
1986 Mercedes-Benz S-Class 300SDL $4,999 228,000 Dealer Sedan Gray
1987 Mercedes-Benz S-Class 300SDL $4,900 315,765 Ditmire Motorworks Sedan Blue
1987 Mercedes-Benz S-Class 300SDL $4,200 -- Classified Ad
1986 Mercedes-Benz S-Class 300SDL $3,950 194,756 Best Import Motors, Inc. Sedan Grey
1987 Mercedes-Benz S-Class 300SDL $2,995 259,114 Individual Seller Sedan White
1987 Mercedes-Benz S-Class 300SDL $2,800 115,000 Individual Seller

SD
1985 Mercedes-Benz S-Class 300SD $9,000 116,000 Classified Ad
1984 Mercedes-Benz S-Class 300SD $4,500 195,000 Classified Ad Sedan Blue
1984 Mercedes-Benz S-Class 300SD $3,990 193,000 Classified Ad Blue
1985 Mercedes-Benz S-Class 300SD $3,800 201,000 Classified Ad Gray .
1983 Mercedes-Benz S-Class 300SD $3,300 -- Classified Ad mi.
1983 Mercedes-Benz S-Class 300SD $3,200 200,000 Classified Ad
1983 Mercedes-Benz S-Class 300SD $3,050 161,000 Individual Seller Sedan Gold
1984 Mercedes-Benz S-Class 300SD $3,000 -- Classified Ad
1984 Mercedes-Benz S-Class 300SD $2,900 167,000 Classified Ad Sedan Green
1985 Mercedes-Benz S-Class 300SD $2,500 135,000 Classified Ad
1985 Mercedes-Benz S-Class 300SD $2,500 232,000 Classified Ad
1984 Mercedes-Benz S-Class 300SD $2,488 171,000 Hughs Wheels & Deals Sedan Silver
1983 Mercedes-Benz S-Class 300SD $2,300 195,000 Individual Seller Sedan Silver
1983 Mercedes-Benz S-Class 300SD $2,000 146,000 Classified Ad Black
1983 Mercedes-Benz S-Class 300SD $2,000 146,000 Classified Ad

Rarely do I ever see an SDL around these parts. I've seen PLENTY of W123's, W116's, and 81-85 W126's. I have run into a W124 300TD, very nice car. I'd trade a W123 wagon for a W124 wagon in 1/2 a heartbeat.

I've found this to be very true as well. The SD has struggled at 10°F. without the block heater. The SDL started at 8°F. and you never would have thought it was below freezing. Just a 30 second glow and it was running in it's usual one second.

82 - very few SDL's were built, thus explaining why there aren't more around. The 617 powered cars were the #1 selling MB throughout the late 70's and through the mid 80's, that's why there are so many around.

Thanks
David

I would, until I was blue in the face. :D

Winter just isn't a problem anymore for the newer diesel engines. If the fuel isn't gell a 603 or newer model, and in good shape will be just as reliable as a gas car in the winter.

The 6 and the 5 have single overhead cams. I think that if you look at examples on the streets you will see more high mileage 603's than 617's. The 617s just tend to wear out, though most of them rust away or are totalled in accidents, however, how often do you see a 617 with over 400k miles without a rebuild? I know of one.

Thanks
David

Just don't forget that the OM617 has 1-12 years over the OM603 and 8-20 years over the 606.

I love my 617, but if I wanted some REAL power from a W123, I'd swap in a 98-99 OM606. A 606 will put out more power STOCK than an OM617 would after a weekend of $$$ and tweaking.

"617s just tend to wear out, though most of them rust away or are totalled in accidents, however, how often do you see a 617 with over 400k miles without a rebuild? I know of one."

Really, I think it's time for some 617 owners to speak up here. There are lots and lots of 617's that have over 400k without a rebuild. I met a guy last winter at our local street fair who was setting up his booth and I noticed his yellow SD. Struck up a conversation with him; 630,000 miles on an 84. Original engine no rebuilds. His tranny was rebuilt at 500,000, even though he said it was still functioning through all the gears, just too rough. There was a thread here about a guy who tore his 617 down at 500,000 miles for a preventative rebuild, but every thing was still to spec, and he just put all the old components back together. Just look around this forum and you will see many high, very high milage 617's. Preventable catastrofic failures caused by timing chain, cooling system, and run-away engines are the biggest threat to the 617. The 617 engine is not one that "just tends to wear out," unless it is completely neglected.

Saw one yesterday with 398k at Pick-N-Pull. :) KKK turbo was on there too, it was an '84 model with a grey interior.

I agree...
I have a 24 year old 282Kmile 300SD (that was NOT maintained properly in its history before me) and it will match a low miles 1996 3.1L V-6 gasser olds coupe in a race off a stop light.
Not an amazing feat but it sure stands to show that it hasn't worn out yet and is showing no indication of doing so anytime soon. :)

My 617 with 220k miles has a scary amount of blow by. I know that car was taken care of to.

I have a friend who is a fellow Mercedes nut. Had a W116 300SD he put over 300,000 miles on. Did 95% of the maintenance himself--Georgia Tech mechanical engineer.

He has now moved on to 560SELs and has two. Says he loves having all that power underfoot. When I asked about the poor mileage, he said even at 17 mpg on premium, his $5000 560SEL is still waaaaaaaaaaaay less expensive to own/operate than a new Corolla.

Sometimes I think people put too much emphasis on fuel eceonomy as part of the ENTIRE cost of owning and operating a car.

Key determinants are who will keep up the car and how often will it need attention. It might be cheaper for your friend to keep up his 560 but not for someone who will take it to a shop. A 560 needs attention more frequently than a Corolla so that's a factor for someone on a tight schedule. I wouldn't think twice about going 12K miles between oil changes in a Corolla if the manufacturer recommends 10K mile intervals. I wouldn't dream of it in the SDL.

I agree with what you say. Look at the purchase premium on an E320 CDI over an E320 gasser (a couple of years ago, anyway) or the premium of a Powerstroke F-350 over a gasser F-350. The difference will probably buy enough fuel and tune-ups for the typical duration of the first owner's use of the vehicle.

Sixto ... tangents? we got tangents
95 S420
87 300SDL

You need to budget another $7500 minimum for either the Powerstroke or the Chevy/Isuzu Duramax diesel engines. $10,000 might be more like it (for the additional charge).

My girlfriend is in the midst of purchasing a 1999 38' Carver motor boat.
It comes with twin Chevy 350 engines and Mercruiser outdrives.

It's not possible to find these boats with diesels unless you go to California or maybe Florida and you are looking at some serious money on top on the price of the boat.

I have spoken with several boat captains and explained I wish we could find my girlfriend a boat with diesels and they said if you are talking about a weekend boat and some fresh water trips and maybe even in salt water every few years, then gas is fine. You won't recoup the price of the diesels.

It all depends on how you use the boat. If you run 50 hours on it a year gas is fine. If you do 200+ a year then diesel makes sense. Also if you fish the boat diesel really is the only way to go.

Another point come time to sell say you have two equal boats with 1,500 or so hours on them. The diesel boat will be worth far more because the engines have several thousand hours of life left in them. 1,500 hour gas engines are at the end of their life.

Unless you do nothing to a W126 and just drive it into the ground I find it hard to beleive that a Toyota would cost more to own.

I drove a 91 300D for over 140,000 when it got totalled. Loved that car and couldn't imagine replacing it. I now have the 6 turbocharged (98 300E td) and it is a whole other vehicle. So much more pep and responsiveness. The newest CDIs are even more incredible.