So I was thinking about pulling the trigger on buying a 91 350sdl. 228 thousand miles, seems to be well maintained, good carfax report. Asking price 5000. What are the pros and cons of this vehicle. I understand the 3.5 liter is prone to problems and not as reliable as previous 300 series diesels, but is this enough of a reason to not pick one up? Are they still decent for a vegetable oil conversion? What does a typical engine overhaul cost on these? I am currently waiting on a mechanic's inspection. Good purchase or no?

Click on search, type in rod bender, start reading.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

That's all you need to know..........
Engine overhaul is about 1 1/2 the purchase price, if you find a good deal. And sometimes they bend a rod too.
Stupid purchase just for a veg. oil conversion.....

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

OK so I have an 82 300d turbo with an engine that has 100k a transmission that has 45000, and a car that was poorly maintained and has enough electrical, vacuum, and interior problems to keep me going for years without ever making it acceptable enough for my wife. I was looking for something better maintained. Should I just hold on to the 82 300d and swap the engine if 3.5 liter craps out? I was planning on selling the 82 300d to someone with more patience. But perhaps it would be worth more to me for just the engine?

Is the 300D solid, or does it have rust issues? For $5K, you can have quite a bit of work done on the 300D in a short amount of time.

The 3.5 has a major risk problem. That said it is a gamble of sorts. Although the engine may be less likely to bend a rod burning vegatable oil as the compression burn or instantainious pressure is less. The pressure just develops more gradually. Little is really understood for sure on why these engines bend rods. Yet there has been endless speculation.
One clue is that there is very little material between the cylinder bores compared to the three litre block. In all likelyhood it is just a three litre with an overbore but they may have gone too far.
Thats why a diesel is quieter on vegatable oil. It has to do with the rate of flame spread being slower or longer if you wish than diesel.
A rebuild of these blocks is basically not a good ideal. Since the earlier 3 litre block is an exact fit I think. A person owning a 3.5 should try to locate a three litre and put it into storage.
They have no abnormal lower end problems. A few site members have done this conversion. Plus when running vegatable oil it never hurts to have a spare injection pump around if it is compatable from the three litre is beyond my knowledge.
Your newer head on that 3.5 engine fits the 3 litre well and is of an updated design from the original three litre heads. You could find a used 3 litre engine and have the lower block rebuilt or use as is if a good one was found. This is how I would look at it. Again if I was to take that gamble I would have a spare three litre lower block on hand. You can always sell the head off it especially if it is one of the later heads to defray some of your cost. In the senario you eventually sell that car and your engine does survive.
The including of the three litre block in the sale should increase the value. Those three litre blocks will be in short supply at some point is another consideration. If you are determined to run vegatable oil at least it could have one possible benefit with this engine. Make sure you understand the use of alternative fuels well prior to doing it. I personally am not a fan of vegatable oil but try to keep an open mind. Best of luck in whatever you decide to do.
It is very important to try to get an answer of how much oil the present owner adds between oil changes or the average amount of miles before he has to add a quart. The less use the better as oil consumption on this engine is directly corelated to the rod problem. That is the warning usually that the problem is underway although the engine will sound fine. Last but not least your present 82 three litre is not the right one for a swap. 1986 and up is what it takes. .

Minor rust, nothing to bad where body panels needs replaced. Big dent on bottom of right front fender. Paint in terrible shape, most of clear coat gone. Interior is in poor shape, Cessna aircraft bucket seats in the front, nice but not right. the 350sdl is just so damn sexy. Its hard not to wish for something a bit better taken care of. Bought the 82 300d for 500 dollars great deal considering engine and tranny mileage. Had a bad rear end. Bought another rear end out of another 300d (not turbo) geared considerably lower I found out later but very solid. Only had 120k on rear end. So a solid drive train throughout. I thought about investing more money in it but the car has been so much work to be done on it that I thought it might just be better to start on something with fewer problems.

OK, I understand the condition of the 300D. If you really want a W126, why not go shopping for a nice 300SDL. IMH, the 350 is probably more risk than it's worth.

So you don't think a engine swap as an insurance policy is the best idea? I knew their must be a reason no one was offering more for this even though it was way below blue book.

Find an OM603 that needs a new head. If your engine bends a rod keep the head from it.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

x2.

The later 126s are very nice cars. The 3.5 does tend to bend rods but it is not an instantaneous failure, but a gradual one which you will have plenty of time to line up a good 3.0 liter block to swap in.

Only buy one for a cheap enough price you can afford to substitute in a good 3.0 liter block.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Some 350SDL's are great. I bought my 1991 new and have no indication of the rod problem after 197K miles, best car I have ever owned, I have owned a lot of cars.