1991 350SDL - PeachParts Mercedes-Benz Forum

Brian Carlton · #1 10-10-2009, 02:19 PM

Took a look at a '91 W-126 today. 150K on the clock.

The vehicle was garaged for most of its life and the body is in excellent condition. Interior is also quite good, but not immaculate due to the mileage.

Maintenance consisted of just the basics.........shocks, brakes, tires, etc. No front end work of any kind.

The engine starts and runs rough with some injector knock. Heavy and extreme oil smoke. The event that precipitated this condition was sudden and instantaneous...........not the typical behavior exhibited when a rod bends.

I'm curious................from those with experience with this engine..........if anyone else had an incident with this engine that caused an instantaneous and dramatic increase in oil consumption.

I might consider purchasing it for the right price (probably about $1K or so).

amosfella · #2 10-10-2009, 03:45 PM

Friend had that problem.... Head gasket....

kerry · #3 10-10-2009, 05:21 PM

Isn't there a picture on here somewhere of that engine with a failed headgasket between an oil gallery and a cylinder with some speculation that the failure was a root cause of the rod bending?

Brian Carlton · #4 10-10-2009, 05:29 PM

Quote:

Originally Posted by kerry

Isn't there a picture on here somewhere of that engine with a failed headgasket between an oil gallery and a cylinder with some speculation that the failure was a root cause of the rod bending?

Speculation of why the rods bend runs the gamut from EGR to insufficient fatigue strength. None of it is conclusive and all of it can be refuted on anecdotal data.

TylerH860 · #5 10-10-2009, 05:29 PM

Quote:

Originally Posted by amosfella

Friend had that problem.... Head gasket....

yup, seen it on two other 350s, including the one I sold.

babymog · #6 10-10-2009, 06:06 PM

For $1k you can sell the head and scrap the rest.

Brian Carlton · #7 10-10-2009, 06:09 PM

Quote:

Originally Posted by babymog

For $1k you can sell the head and scrap the rest.

It's way too nice to scrap.

I need to determine a price to offer him for it. The real question is its value with a "bad" engine.

amosfella · #8 10-10-2009, 08:30 PM

The blown headgasket can often be the result of overheating.... If the engine blows, drop a 3.0 into it.... no problems, should just about plug and play... offer $800....
They say that the rod bending problem in the 3.5 is caused by a low cetane level in the fuel.... At least that's mercedes' official story.... Could be true, as I have been told that the 3.5l has an excellent reputation in europe....

GregMN · #9 10-10-2009, 08:39 PM

I just paid $800 for one with a warped head. When I am done dealing with that issue, I will have spent about 70% of what I think it was worth if it had no issues. This does not include any value of my labor (and that may be the correct value). So, if you like projects and risk, then go for it. If you want a an economic analysis, you may be better off finding one that does not currently have any issues. (It will have issues later, possibly on the drive home after handing over the cash to the PO).

I bought it with an engine transplant in mind as the worse case. That might be a good way for you to approach this one. The owner thinks it needs a new engine, you think it's just the turbo seals. Roll the dice.

Brian Carlton · #10 10-10-2009, 08:45 PM

Quote:

Originally Posted by GregMN

I bought it with an engine transplant in mind as the worse case. That might be a good way for you to approach this one. The owner thinks it needs a new engine, you think it's just the turbo seals. Roll the dice.

That's my thoughts as well. But, I doubt that it's turbo seals this time.

The question is what to offer him for it. He's asking $5K but he knows that's ridiculous...........he fully understands the cost of a new engine...........the vehicle was "diagnosed" by the dealer.

I'm inclined to offer him $1200. due to the excellent condition of the body. He'll take it if nobody else is interested. I don't think he can get that much in scrap value.

Graplr · #11 10-11-2009, 01:10 PM

Quote:

Originally Posted by Brian Carlton

That's my thoughts as well. But, I doubt that it's turbo seals this time.

The question is what to offer him for it. He's asking $5K but he knows that's ridiculous...........he fully understands the cost of a new engine...........the vehicle was "diagnosed" by the dealer.

I'm inclined to offer him $1200. due to the excellent condition of the body. He'll take it if nobody else is interested. I don't think he can get that much in scrap value.

Whenever I have room in the garage I hope to buy a very nice shape 90-91 126 with a bad engine.

If it were me and I had the room, I'd do it for $800-1200. I think you are about right with a $1200 offer. The one that Greg bought was pretty nice as well but the head was for sure blown and the owner was only asking $1500 to begin with.

Fulcrum525 · #12 10-11-2009, 01:31 PM

I'll never forget one time when my turbo went bad. At idle the car would shake violently and would start to billow smoke out the tail pipe as it burned oil. However once you started driving it all would be fine until you stopped again.

Its probably not the same problem as the one your looking at but its still a possibility.

Brian Carlton · #13 10-11-2009, 03:31 PM

Quote:

Originally Posted by Graplr

Whenever I have room in the garage I hope to buy a very nice shape 90-91 126 with a bad engine.

If it were me and I had the room, I'd do it for $800-1200. I think you are about right with a $1200 offer. The one that Greg bought was pretty nice as well but the head was for sure blown and the owner was only asking $1500 to begin with.

I need another W126 like I need a hole in my head. But, for $1200. I probably cannot resist it. I'll have to get rid of the second '86 SDL from CA.