hello,i would like to know about Mercedes turbo diesel and non turbo diesel engines which one will last longer as the same cares and services,
i know turbo is faster.Again thanks alots all yours helpful inputs

No practical difference in life expectancy. With proper care, either will last longer than you'll be interested in it.

Sixto
95 S420
87 300SDL

The turbo engines are more complex, so there's a little more to break, but in fact I've seen little difference in the longevity of the turbo and non-turbo engines. The non-turbo engines require a little less costly maintenance in MY opinion. I've owned/maintained 9 normally aspirated and 4 turbo diesels over 35 years and driven them almost a million miles.

Marshall

i have a 300D 1978 non turbo and it seems to work pretty well throughout the years my dad had it. He had given it too me since it was his first car here in the U.S instead of just junking it out to the yards. I have done several repairs on it since then..but most of the jobs that i have done were not that hard (I.E: oil changes, injectors, fuel filters). the Non-turbo is a very reliable car. have no idea about the turbo version though. If you read the forums here a little bit more about turbo repairs on the later 300D 80's and higher (model W123), some of them can get a little ugly; almost to the point where its not feasible to fix the car anymore. I have almost close to 300,000 miles on my 300D 78 and i have replace all 5 injectors once and did the timing chain once just recently. As long as you can keep oil to the respectable levels in either W123, the car should be a lifer......granted that suspension and other things are kept clean

d4ever,

When MB started making turbo engines, they didn't just say "hey Fritz, hang a turbo on all the Diesels from now on".

THe turbo Diesels were "hardened" to withstand the extra pressure and heat turbo charging causes in an engine. Such things as oil cooled pistons, nitrided crankshaft, sodium filled exhaust valves, and carbide cam followers were added to make the turbo engines as reliable as the non turbo engines.

This is what worries me about these turbo kits that are sold as add on kits for Diesel pickups. The original engines were not designed to be turbocharged so I wonder how reliable the engines will be when an add on turbo is used.

P E H

Lots of Mercedes '70s 220D/240D and 617.91 300Ds had turbos hung on them. They generated about half the power increase that the factory turbos delivered but reliability suffered and many engines failed within tens of thousands of miles of the turbos being installed. I know mechanics that serviced those engines and in retrospect they were NOT very complementary about the modifications.

Marshall

The diesel engine works exceptionally well turbocharged. These engines need the additional air to get the fuel to burn as completely as possible. The mechanism to get there is simpler than it is with gasoline powered vehicles. The fuel mixture does not change rich/lean with every temp and pressure change. The engine does need more fuel as the boost goes up, but that is more of less an easy matter to solve, and is done well with the ALDA. With gassers the mixture requires constant fuel adjustments to get the fuel/air mixture correct.
Besides that there is a long history with the turbocharged diesel engines, and most of the problems have been worked out. Mercedes has been careful not to build any GM diesels, at least so far. That is a good thing.

I'm not quite as impressed with the MB Diesel engines are you are......

The 603 head failures and rod bending issues, while not quite as bad as GM's 5.7 gas engine conversion, are horrible oversights for a car company that wants (or should I say used to want) to be known for engineering excellence.

Mercedes did the right thing when they offered to replace every trap oxidizer presented to a MB dealer, they should do the same thing for head failures caused by the trap AND the later 603 series engines that have bent rods. I wonder if the reason for the fantastic replacement policy on the trap-oxidizer was due to federal emissions rules...

PEH

OM616 and non turbo OM617's also have hardened journals and sodium valves, the big turbo change was the oil cooled pistons.
IMHO anybody dumb enough to hang an aftermarket turbo kit on an engine that was not designed for turbocharging deserves what they get.

Good point. The 6 cyl MB diesel was not nearly as bad as the GM, but that would not be any consolation to the owner of one that bent a rod .

All the problems with the GM 5.7 diesel.....(no it was not a gas conversion such as popular opinion states) was due to head bolts that stretched and lead to head gaskets popping........something that took them too long to identify and fix. The block was NOT a off the shelf casting used on other motors.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I don't know about that, had two GM diesels toss parts right through the block on mine. Was told by many at the time this was a warmed over Olds Rocket 350 block. May have been or may not have been, all I know for sure is it was less than reliable. Had many other problems besides that, as if it needed any more problems anyway.

Mercedes redesigned the OM603.96 heads and by '89 there were no longer any problems with heads cracking under usual conditions. Most original owners that had head failures out to 100kmi/10 years got a new head under warranty and the same was true of most OM603.97 engines with rod problems. Mercedes solved the rod problem - virtually NONE of the rebuilt engines have failed of of the few that have - it wasn't rods that went. They did what they were obligated to do under the warranty that was issued when you bought the car. In the case of MOST original owners, they went even further.

As to Mercedes doing the "right thing" relative to the trap oxidizer - Mercedes issued the trap recall to satify the EPA and to prevent being sued into bankrupcy or being barred from doing business in the US. They created an emissions system that didn't last as long as they expected it to and so they offered a warranty that required replaceemnt of the trap and related exhaust parts as long as the car was in service.

That was beginning to cost a LOT of money in traps and turbos (I had gone thru 4 traps and had the 3rd turbo installed when the trap was removed and replaced with the CAT in 1997). By now I would have used up at least 3 more traps and probably another turbo or two. Occasionally an engine would be destroyed if the EGR was open when the trap blew out! That was ALL warranted to satisfy EPA and was getting REALLY expensive. They put in the CATs and now when something fails - it's YOUR nickle and not theirs.

Marshall

Marshall

Thanks for the info - I suspected the response for the trap oxidizer was motivated by something more than concern for the customer.

That said I'm glad the MB has replaced many 603 heads and blocks - I think they should adopt the same replacement policy they were forced to use for the trap oxidizers. Of course I do realize its easy for me to say this since I'm not paying for the replacements.

Lets hope the days of Diesel engine failures in MB cars are behind us.....

As for the 5.7 Diesel I also have had direct experiences with rods coming thru the block on low mileage/well maintained cars - I do not know for a fact that the 350 block/crank is a re-worked 350 gas engine but I can say that the problems with the engine were not confined to head bolts/head gaskets.