W126's? Diesel content

[Arizona_928]

Any of guys own(ed) one?
I just looked at one owner high mileage 300SD with maintenance records since new.
It has peaked my interest in these old Mercedes diesels...

[speeder]

I’ve owned every edition of w126 diesels, 5 and 6 cylinder, long and short WB, etc. What do you want to know?

[Arizona_928]

How many miles do those om617's last. High failure parts?

[speeder]

Originally Posted by AZ_porschekid

How many miles do those om617's last. High failure parts?

They are very durable engines but the lifespan of one depends very heavily on how well they are maintained, just like every other engine ever made. People love to crow about them being "500k engines" but I've seen them fail w 100k miles. Poor maintenance can really kill a diesel, any diesel.

With reasonable maintenance, they go a couple hundred thousand miles before starting to lose some compression and develop blow-by. In fact, the most important test to do on one you are considering is to open the oil cap with it running and see how much wind comes out. You should be able to lose the cap and it should stay in place w the engine idling. If an OM617 has good compression, it can be made to run and perform like new w other tuning and maintenance items performed.

There are not really any high failure rate parts in the engine but for the rest of the car, there is the usual laundry list of things that go bad on an old German car from the climate control to the vacuum system to interior pieces to...

The good news is that they are not too bad to work on and parts are still widely available. Post some pictures and more info about the car here and I'll watch the thread and offer my input.

[tdw28210]

The old skool guys will say the w123's were the last of the REAL Mercedes diesels. (they are are the preferred civilian taxi vehicle in most war zones). I own an w212 and still really like it after 80k miles. Even though the oil cooler seals recently failed and it puked a couple quarts onto the driveway. 39 mpg on the highway and tons or torque.

This one is in the sweet spot. Pre-EGR turbo diesel technology with bullet proof early diesel DNA.

https://www.cargurus.com/Cars/l-Used-1980-Mercedes-Benz-300-Class-300SD-Turbodiesel-t55414#listing=226726280

[slow&rusty]

I've never owned or worked on a W126 Diesel (only the gas model), but this chassis is one of my favorite cars, so looking forward to seeing pictures and specifically the model that you are interested in.

[speeder]

Originally Posted by tdw28210

The old skool guys will say the w123's were the last of the REAL Mercedes diesels. (they are are the preferred civilian taxi vehicle in most war zones). I own an w212 and still really like it after 80k miles. Even though the oil cooler seals recently failed and it puked a couple quarts onto the driveway. 39 mpg on the highway and tons or torque.

This one is in the sweet spot. Pre-EGR turbo diesel technology with bullet proof early diesel DNA.

https://www.cargurus.com/Cars/l-Used-1980-Mercedes-Benz-300-Class-300SD-Turbodiesel-t55414#listing=226726280

They do not know what they are selling. That is a 1980 300D, (non-turbo), not a 300SD, which was a turbo in 1980 and had an EGR, FWIW. I had a 1980 300TD wagon, (same car), that was in almost unbelievably good condition. 116k miles and drove like brand new.

All of the old iron head diesels were good motors but technology has really left them behind. I drive a 2006 Jetta TDI that is just light years ahead of those cars in any possible metric of measurement. Performance/efficiency/quietness/emissions/etc.

[Arizona_928]

Originally Posted by speeder

All of the old iron head diesels were good motors but technology has really left them behind. I drive a 2006 Jetta TDI that is just light years ahead of those cars in any possible metric of measurement. Performance/efficiency/quietness/emissions/etc.

In my honest opinion. Except fit and finish. Plastic interiors and made in Mexico quality has nothing on those old MB. I'm actually getting tired of my ALH tdi.

I bought the one I was looking at. 1984 300SD. No blow by, no smoke. Some issues that didn't present itself until I got home. I'll go through it and post some questions when I get a chance to one over everything.

[da Vinci Dan]

I have owned 3 diesel Mercedes. Dealer incorrectly ids it as an SD - it is a w123 NOT a 126. Not sure how much I would trust their aditional insight past this. This example from the pics needs both front seats rebuilt. Figure $1k each. Poorly glued on interior wood trim unfortunately has destroyed original and very expensive to replace pieces. Paint on roof is toast and likely is or will soon be on others surfaces. They very carefully mention body area rust thus dismissing undercarriage issues. Rust on the rail is only mentioned. Invariably This is accompanied by front and rear quarter rust and rust on vital unibody components.

Sure the engines are strong. But contrary to internet lore, they do not last forever. Valves, heads, injectors etc... often go an require big dollars to repair. If you bought this car new in 1980 and took prefect care of it, it would do many hundreds of thousands of miles. Now, it is an old piece of highly engineered machinery with an uncertain past. Similar to an old 911, you need to love it and DIY or have an open checkbook for someone else to do this.

TMU...

Way over priced but a clever attempt to mislead an unknowlegable person.

Pass on it and check out the w123 forums.

If you wanted to diy... maybe offer $4000

[tdw28210]

Originally Posted by da Vinci Dan

I have owned 3 diesel Mercedes. Dealer incorrectly ids it as an SD - it is a w123 NOT a 126. Not sure how much I would trust their aditional insight past this. This example from the pics needs both front seats rebuilt. Figure $1k each. Poorly glued on interior wood trim unfortunately has destroyed original and very expensive to replace pieces. Paint on roof is toast and likely is or will soon be on others surfaces. They very carefully mention body area rust thus dismissing undercarriage issues. Rust on the rail is only mentioned. Invariably This is accompanied by front and rear quarter rust and rust on vital unibody components.

Sure the engines are strong. But contrary to internet lore, they do not last forever. Valves, heads, injectors etc... often go an require big dollars to repair. If you bought this car new in 1980 and took prefect care of it, it would do many hundreds of thousands of miles. Now, it is an old piece of highly engineered machinery with an uncertain past. Similar to an old 911, you need to love it and DIY or have an open checkbook for someone else to do this.

TMU...

Way over priced but a clever attempt to mislead an unknowlegable person.

Pass on it and check out the w123 forums.

If you wanted to diy... maybe offer $4000

Yeah, did not look very closely. That ad is pretty FUBAR'd. But this one...THIS ONE HERE...is a real deal 116 "Sonderklasse" (early S class) Turbo Diesel with what should be the non-EGR motor. And the last year the 116 was made too (I think), hmmmm.

https://classics.autotrader.com/classic-cars/1980/mercedes_benz/300sd/101033655

[speeder]

Originally Posted by tdw28210

Yeah, did not look very closely. That ad is pretty FUBAR'd. But this one...THIS ONE HERE...is a real deal 116 "Sonderklasse" (early S class) Turbo Diesel with what should be the non-EGR motor. And the last year the 116 was made too (I think), hmmmm.

https://classics.autotrader.com/classic-cars/1980/mercedes_benz/300sd/101033655

Ahhh, no. You can clearly see the EGR in the main engine photo. It's on top of the manifold in the front on RH side. That's a nice car but they really don't pull big $$.

I had a '79 for a DD for years, let me see if I can dig up some photos.

[speeder]

I still see this car once in a while, sold it to an acquaintance. Rare color combo.

[VincentVega]

I great up working on them, some good memories. Not much interior room considering how big they are but they are great highway cars. Glow plugs, injector lines, valve adjustments, oil pan gaskets... used to do that in my sleep. Make sure you know where the engine kill in, door lock actuators will fail.

Cool cars, dont see many around here anymore.

[legion]

I still miss my 300D...

[Arizona_928]

here's the land yacht.
Only issue I've found was looks like a fuel damper bolt. Little shaky at idle when hot. pelican has one for 35$ so I'll order one tomorrow.
300k mi, with no blow by, or smoke. Gonna be a keeper.

[tdw28210]

Those bumpers make the 911 black globs look dainty. and those cat-eared headrests are still awesome.

[jyl]

You a rapper now!

Seriously, cool car. The quality of the old MBZ is great. We loved our W123.

[Arizona_928]

Originally Posted by jyl

You a rapper now!

Seriously, cool car. The quality of the old MBZ is great. We loved our W123.

That or start a YouTube channel. I do have a gopro... Hahah

[vonsmog]

Who would want to own an old Benz..........................................Oh, never mind!

[Arizona_928]

Oooh... Always had a soft spot for the wagons.