What Make a Real Diesel - Page 2 - PeachParts Mercedes-Benz Forum

ForcedInduction · #16 01-22-2011, 06:40 PM

Quote:

Originally Posted by Bob Kerstetter

Cummings

No such thing.

Quote:

Originally Posted by compu_85

I feel the perception that modern computer controlled diesels are "weak" or "unreliable" is unwarranted.

Its true, but its not necessarily the engines themselves its the emissions equipment and the heat/stress they put onto it.
I work with Buses, the ones that are 11 years old still (mostly) start and run great with just the usual age related issues (wiring harness corrosion, chassis wear, occasional injection pump failure and air compressors bypassing oil into the air system). However the 2006 and 2008 models have a DPF (06 passive, 08 active regeneration). They're constantly having DPF problems, the 08 models especially have had a few exhaust valve failures from the regeneration heat and transmission issues from the higher coolant temperature (200*f) not removing enough of the heat put into the ATF from the retarder.

Get rid of the particulate filter and cat from modern engines and they're just as reliable.

compu_85 · #17 01-22-2011, 07:34 PM

Quote:

Originally Posted by layback40

The older motors are so simple in their operation & control. As soon as you have an electronic/ mechanical interface you have a potential problem. Electronic gear does not have the longevity/reliability of the simple mechanical stuff.

I don't think this is true. And when you say "simple mechanical stuff" you are glossing over a lot of the mechanical precision required to make a purely mechanical car run properly.

I'll concede this: Given poor upkeep / wear a mechanical car will probably continue to run poorly longer then an electronically controlled one.

Also, Re: Scan tools... I guess VW guys are spoiled to have VAG-COM. But AutoEnginuity is getting better and better, their Mercedes support is getting very good.

DPFs are engine killers. They were on the 85-87 Mercedes cars, and they are now.

-J

Diesel911 · #18 01-22-2011, 07:44 PM

Quote:

Originally Posted by compu_85

Yes, the 80s 4 5 and 6 cylinder VW IDI motors do like to develop cracks between the valves, but it doesn't really affect anything. Glow plugs getting stuck in the 606's head is a problem I'd forgotten about.

I wouldn't call the computers a "black box". It's not fair to call torx fasteners complicated if all you had was a flat blade screwdriver, similarly you just need the right tools to test and fix modern electronics. I'd hardly consider myself a "trained person" in that regard, anymore then most of us shade tree mechanics could consider ourselves trained on mechanical systems. I've just done my reading and fiddling, so I understand how they work.

-J

I used the phrase "black box" because to the average owner of a Car what controls his Engine is now partly dark (black) and mysterious; with out the training or access to equipment paying someone to trouble shoot things controlled by the Black Box is going to be expensive.

My comment on the cracked VW and Volvo Cylinder Heads was given as an example of Aluminum being a less suitable material for Diesel Cylinder Heads that the more typical Cast Iron ones.

No crack in a Cylinder head is good; even if the FSM said you can have one.

busman1965 · #19 01-22-2011, 08:28 PM

I would have to say the old stuff is vastly superior to the modern engines in overall longevity and durability. I captain a 40 year old sportfish boat that has 12-71 Detroits with 15,000 hours on them, and they have never been rebuilt!!! Sure they burn more fuel than a modern engine, and weigh more, but I push the starters and they fire right up, dont smoke and still have good oil pressure! I have worked on many Gardner diesels that have 200,000+ hours on them, and run like a watch. The modern "high speed" diesels are lucky to make 5000 hours between rebuilds.

There is no way a modern engine can last like the old stuff does, when you ask for more horsepower out of a smaller lighter engine at higher RPM's, it has to wear out quicker, as everything runs hotter, on smaller bearing areas.

I work on alot of Mann and Mtu engines in other boats, and am not impressed with the computer controlled modern engines. They make it easy for 'Parts Changer" type mechanics to fix them, but any old-time mechanic will always prefer an engine that you can adjust various parts to account for wear, rather than replacing the entire piece.

It seems unlikely that any modern cars will show the longevity that the old 180/190D Mercedes from the 50's or the 240/300D have shown. I have seen numerous 180/190d that have topped 700,000 miles and are pushing 50+ years old. I will be suprised to see any 30+ year old cars in the future, out of the current crop of computer controlled diesels............

By the way, marine engines actually take much more abuse than do vehicle engines. Marine engines essentially operate like a vehicle engine would, accelerating up a steep hill, all the time, under full load. This is why they only use a very few car engines in marine service, such as the 4 bolt main small block chevy, and the English Ford Diesel. Many of the car/truck engines simply will not take the steady beating that operating at full load induces.

I don't want to seem a grumpy old buzzard, I just am passing along my observations from a life spent under hoods and in enginerooms, fixing stuff.

casioqv · #20 01-22-2011, 09:14 PM

I personally draw the line on "real diesels" by weather or not it can run with a total electrical system failure. The OM60x engines have aluminum heads and computer controlled idle, but they still run fine with the computers disconnected.

I do think aluminum head diesels are more likely to blow head gaskets even if they're never overheated (I'm doing the one on my 190D now) but I think a head gasket every 200-300k miles or so is a cheap price to pay for no valve adjustments, significantly better fuel economy, and more power compared to the old fully mechanical iron head diesels.

locry · #21 01-22-2011, 09:26 PM

bottomline.... during a zombie apocalypse... what would you rather have with you?

compu_85 · #22 01-22-2011, 10:00 PM

Zombies: The benz (heavier, better for running over the undead)

Nuclear: A Mk2 Jetta NA diesel with a manual fuel cutoff solenoid (Easier to fix, better range per tank)

casioqv · #23 01-23-2011, 12:22 AM

Quote:

Originally Posted by locry

bottomline.... during a zombie apocalypse... what would you rather have with you?

Probably a W115 stickshift 240D... but I don't think I'd even keep that running long without forums like this, and parts suppliers

Doktor Bert · #24 01-23-2011, 12:37 AM

The 2-Stroke Detroit, with its 4 exhaust valves per cylinder and no intake valves, always impressed...especially the 12V71.

The Deutz Air Cooled Diesel was my #2 favorite....

Doktor Bert · #25 01-23-2011, 12:38 AM

Quote:

Originally Posted by busman1965

I would have to say the old stuff is vastly superior to the modern engines in overall longevity and durability. I captain a 40 year old sportfish boat that has 12-71 Detroits with 15,000 hours on them, and they have never been rebuilt!!! Sure they burn more fuel than a modern engine, and weigh more, but I push the starters and they fire right up, dont smoke and still have good oil pressure! I have worked on many Gardner diesels that have 200,000+ hours on them, and run like a watch. The modern "high speed" diesels are lucky to make 5000 hours between rebuilds.

There is no way a modern engine can last like the old stuff does, when you ask for more horsepower out of a smaller lighter engine at higher RPM's, it has to wear out quicker, as everything runs hotter, on smaller bearing areas.

I work on alot of Mann and Mtu engines in other boats, and am not impressed with the computer controlled modern engines. They make it easy for 'Parts Changer" type mechanics to fix them, but any old-time mechanic will always prefer an engine that you can adjust various parts to account for wear, rather than replacing the entire piece.

It seems unlikely that any modern cars will show the longevity that the old 180/190D Mercedes from the 50's or the 240/300D have shown. I have seen numerous 180/190d that have topped 700,000 miles and are pushing 50+ years old. I will be suprised to see any 30+ year old cars in the future, out of the current crop of computer controlled diesels............

By the way, marine engines actually take much more abuse than do vehicle engines. Marine engines essentially operate like a vehicle engine would, accelerating up a steep hill, all the time, under full load. This is why they only use a very few car engines in marine service, such as the 4 bolt main small block chevy, and the English Ford Diesel. Many of the car/truck engines simply will not take the steady beating that operating at full load induces.

I don't want to seem a grumpy old buzzard, I just am passing along my observations from a life spent under hoods and in enginerooms, fixing stuff.

Here!!! Here!!!!

casioqv · #26 01-23-2011, 03:14 PM

Quote:

Originally Posted by ForcedInduction

No such thing.

http://marine.cummins.com/mrn/public_cummins/content.jsp?tlaId=190&marketId=13&menuId=1&menuIndex=0

busman1965 · #27 01-23-2011, 10:35 PM

Bert, I agree the 12-71 is a heck of an engine, pretty much as simple as you can make a big diesel. The Deutz is also an amazing machine, they seem to go forever.

My other personal favorite is the old Lister diesels from England, huge, heavy, turn really slow, and loads of torque.
I saw a 8hp Lister in the Bahamas that had been running a generator for decades. The owner used to shut it down a couple times a year to change the oil.....thats about all he ever did as far as upkeep. Of course it is hard to wear out an engine that weighs 1000lbs and only makes 8hp at 650rpm!!

W124 E300D · #28 01-24-2011, 05:57 AM

Quote:

Originally Posted by busman1965

My other personal favorite is the old Lister diesels from England, huge, heavy, turn really slow, and loads of torque.
I saw a 8hp Lister in the Bahamas that had been running a generator for decades. The owner used to shut it down a couple times a year to change the oil.....thats about all he ever did as far as upkeep. Of course it is hard to wear out an engine that weighs 1000lbs and only makes 8hp at 650rpm!!

I used to run them, 6bhp @ 650 rpm, 8 @ 800 rpm, from a single cylinder 1.4 litre engine with variable compression, ricardo indirect injection, twin external flywheels each weighing 350 lbs, so your ,1000lb weight is considerably under... the gen head also had a flywheel in the pulley that weighed a further 200 lbs, vee belt (twin) drive to the gen head from the flywheel on the motor, 6 bhp set produced 2.5 kva at unity power factor, and burnt a gallon every 4 hours on full song.