I have a 1982 300sd turbo which I love. Runs great. I recently came across a beautiful 1990 350 SDL (I know, the infamous rod bender) and bought it. I went against my better judgement. It was just to nice to walk away from. It has 139,750 miles on it and I just drove it 300 miles, mostly highway and it seems to run perfect.
My questions to the group are:
1. are there any of these engines that do last
2. are there any know preventative measures one can take to increase the longevity
3. is it correct that if driven mostly highway miles rather than city it may last longer
4. how long can I expect this engine to last given gentle treatment and regular oil (Amsoil marine diesel 15-40) changes
5. what will be a good replacement engine. Will the 5 cylinder bolt up to the trans and everything else, Or is there a factory replacement for this 350

The body, interior, chrome and electrical are all like new. This car rides beautifully, not a squeak, rattle, wind noise or shimmy. I'm willing to take the financial hit for a replacement engine if and when the time comes. This is a car I would like to keep for the next 10 years or longer. I do keep some of my cars for a long time. Have had (and still have) my Grand Cherokee since new in 1993 and my 1959 Tbird convertible since 1972.

Best regards,
squarebird59

Many opt to stick in a 3.0L 603 motor, it's what I would do. All of the last years of the W126 parts (seats, stereo, etc) with the more reliable six cylinder motor.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

1. At least 50% of them have no problems.
2. Disconnect and plug the EGR........but.......this is just a theory.......it's certainly not "known".
3. Again, another theory.........not proven.
4. If a rod doesn't bend, it can last 400K miles.
5. The five cylinder won't bolt up to that trans. The replacement is the same factory 350 engine, or the similar 300 engine. Some folks have found a good used 3.0L engine and installed it with decent results.

the coop im in the leader bought a low mile 350SDL and this summer he is tearing the engine apart and putting upgraded rods in. its a great car just the engine design was flawed.

So you can upgrade the rods to aftermarket ones and be done with it ?

i dont know alot about the 3.5 litre diesel engine in those cars but ive heard stuff like that. and i want to say the rods are mercedes benz upgrades .. brian carlton would know more about that than me.. im an om617 person

The block is about 0.080" over MORE than the 3.0L... that's a lot for an over bore on an already thin walled block.

If your pal is tearing it down, I'd like to see the 3.5L crank in a 3.0L block.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]