the best diesel engine of the 70s-80s - Page 2 - PeachParts Mercedes-Benz Forum

BillGrissom · #16 11-09-2021, 11:30 AM

I think you are correct to look at the non-turbo diesels for more longevity. I suspect those were the "1M mile engines". The turbo can quickly ruin an engine from overheating the aluminum pistons, as true for gas engines too. The OM617 turbo has special pistons with oil-squirters underneath, but if boost is set too high, even that won't suffice (be careful messing w/ boost setting and ALDA). The turbo version also has a chain-driven oil pump which adds complexity (plastic guide rail fails). My 1985 CA turbo engine failed at 330K miles (chunks missing from pistons). Prior owner was a lady who had it religiously serviced at M-B dealer (thick folder w/ high bills) and I always drove it carefully.

I think all 1986+ diesel engines had aluminum heads and/or blocks, which can be damaged by a single overheat. The 1986+ 6 cyl diesel is much more powerful, but seems less reliable. The ~2004 CDI common-rail diesel engines are much more powerful and efficient, but much more complex. A 1970-80's non-turbo engine is much easier to work on, as you can much more easily swing a wrench in the engine bay. If you do need to rebuild the engine, new pistons are affordable (though not like a small-block Chevy V-8) vs the >$500 each turbo pistons if you can even find a set. Accelerating fast is over-rated. Most people just want to get to work dependably. If you live in L.A., a Lambo is a waste as you will rarely see average commute speeds above 10 mph on I-5 and I-405.

jay_bob · #17 11-10-2021, 07:03 AM

"the best diesel engine of the 70s-80s"

The GM gas to diesel 'conversion' ...
- said no one ever

Sorry had to throw that out there. Dad had a '79 in an Olds Delta 88 "Royale". With extra cheese. The seats were like overstuffed sofas. Maneuvered like a pontoon boat.

Summer of 81. I was 16 about to get my license. It was dad's company car and they rotated them out every 2 years. He had arranged to buy it out from the company (leasing wasn't a thing back then like now) and was all set to give it to me after I passed my test. So yeah I have had the diesel bug since forever.

In his last week of driving it the engine grenades. Luckily he had just pulled off the interstate heading home.

I end up getting a rust-rotted (in Chicago, everything was rust rotted) 76 Ford Maverick as my HS driver.

t walgamuth · #18 11-10-2021, 08:24 AM

Two valve Cummins would be many folks choice I imagine.

BillGrissom · #19 11-10-2021, 04:08 PM

Quote:

Originally Posted by jay_bob

The GM gas to diesel 'conversion' ...
- said no one ever

True, but I have read that by the last year, GM had worked out the kinks so it was fairly reliable, but the PR damage had been done. Another case of GM rushing out a product too early, like the infamous Vega aluminum block with no steel liners. I vaguely recall the main problem with the diesel engine was failing head gaskets and the solution was redesigned head bolts (more, thicker, don't know). You think they would have learned to focus on the head gasket after the Vega engine debacle. Lore has it that their diesel was a converted gasoline engine, but I have read that isn't true nor fair, and GM had prior experience producing diesels, so blame management rushing more than the engineers.

240D.Bill · #20 11-10-2021, 05:12 PM

Quote:

Originally Posted by BillGrissom

Lore has it that their diesel was a converted gasoline engine, but I have read that isn't true nor fair, and GM had prior experience producing diesels, so blame management rushing more than the engineers.

Yeah they had some experience but the -71 series never really took off, wouldn’t have helped us win the war, didnt power the free world for the next 40 years, and it couldn’t possibly continue serving as workhorse for countless developing nations today. can’t say they didn’t make an effort though. 😉

240D.Bill · #21 11-10-2021, 06:04 PM

Quote:

Originally Posted by t walgamuth

Two valve Cummins would be many folks choice I imagine.

My ‘91 Dodge has a little over 300k with the 12 valve 5.9 B series and I’m tiredof buying replacement parts. The first was a new injector because one wasn’t peeing straight after 275k miles. The other five were still doing what they should and popped within spec. At 300k I had to buy a new timing cover gasket and seal. I didn’t have any leakage but I had just joined a cummins forum when I learned about the notorious ‘killer dowel pin’. Mine was snug and tight but since I was in the neighborhood I replaced seal on the case cover for peace of mind. Aside from regular oil, filter, and the occasional valve adjustment that engine is tight with no indication of giving up anytime soon.
I must confess to one Huge problem that’s plagued me ever since new: I so often hear of those complain, “The Dodge is falling off the engine.” I’ve yet to but any replacement parts for the pickup. Maybe I’m just lucky.

t walgamuth · #22 11-10-2021, 09:10 PM

Love the cummins!

Purple Guy · #23 11-12-2021, 01:46 PM

Quote:

Originally Posted by 87tdwagen

There is a wide difference in the OM61x range, a 4 cylinder N/a vs 5cyl turbo are miles apart in terms of daily driving. It all depends on what you are looking for the car to do and where you drive and how much maintenance you want to do.

Live in the flatlands of Florida and take the car out to buy your weekly lottery ticket at the local convenience mart, a 240d would last you a lifetime. Daily commute in the major metropolis beltline...a 617 turbo would be a better option. If you drive a lot, you will need a lot of valve adjustments on the 61x engines. The OM60x engines dont require that adjustment process. All have their pros and cons, but start first with defining your specific needs/wants and find the option that best fulfills those later.

but I don't care about the 617 turbo, since everyone knows that they are more prone to have problems; I was asking if a NA617 is more durable than a 616/615 or viceversa

Purple Guy · #24 11-12-2021, 01:51 PM

sorry if I didn't specify but I don't care about perkins or cummins engines

87tdwagen · #25 11-12-2021, 03:08 PM

Quote:

Originally Posted by Purple Guy

but I don't care about the 617 turbo, since everyone knows that they are more prone to have problems; I was asking if a NA617 is more durable than a 616/615 or viceversa

You have not yet defined the job you are looking to achieve. Your question is therefore impossible to answer. You asked which is the best hammer, a cobblers, framing or sledge. All will hammer, but some better than others depending on the job you need it for. Hammering is NOT a job, it is a function.

The OM61x are All fine engines, all are very durable if maintained and set to work in a job where they are efficient and not abused. All of these engines can be both utterly reliable or utterly horrific depending on what is asked of them. So until that is defined, there is no "right" answer.

Purple Guy · #26 11-12-2021, 03:15 PM

Quote:

Originally Posted by 87tdwagen

You have not yet defined the job you are looking to achieve. Your question is therefore impossible to answer. You asked which is the best hammer, a cobblers, framing or sledge. All will hammer, but some better than others depending on the job you need it for. Hammering is NOT a job, it is a function.

The OM61x are All fine engines, all are very durable if maintained and set to work in a job where they are efficient and not abused. All of these engines can be both utterly reliable or utterly horrific depending on what is asked of them. So until that is defined, there is no "right" answer.

so you mean that the number of cylinders in 61x engines doesn't matter?

87tdwagen · #27 11-12-2021, 04:52 PM

Brandon be thy name
No matter how many cylinders you start with, you will always be firing one less.

sgnimj96 · #28 11-13-2021, 10:05 PM

VW's legendary 1.6 diesels were amazing
and continue to amaze more than 30 years later.

t walgamuth · #29 11-14-2021, 08:39 AM

Quote:

Originally Posted by 87tdwagen

Brandon be thy name
No matter how many cylinders you start with, you will always be firing one less.

All the 61x engines are equally durable more or less. The best though is probably the 617 Na. It runs a taller diff than the 616 thus turns less rpm per mile.

The turbo engine is great too but the increased temp makes the durability suffer. They often need head gaskets around 300K miles.

WDBCB20 · #30 11-15-2021, 02:56 PM

Quote:

Originally Posted by t walgamuth

All the 61x engines are equally durable more or less. The best though is probably the 617 Na. It runs a taller diff than the 616 thus turns less rpm per mile.

The turbo engine is great too but the increased temp makes the durability suffer. They often need head gaskets around 300K miles.

Best all-round more likely is the also NA OM602.912. Same or greater longevity than the OM617. Paired with the manual 5 speed gets you a considerably more efficent 35mpg. Hydraulic tappets unlike OM617 gets you self adjusting valves.