Hello,

I have a theoretical question. If you were to buy a 350sdl and the motor was shot, what engine options do you have? If you don't want to rebuild or replace the rod bender, can you use the 3.0 5 cylinder for the 81-85 300sd (is that 617?) or do you have to use the 3.0 6 cylinder from the 86-7 300sdl?

Thanks,

David


www.blackandwhitecookies.com

__________________
My Fleet

1987 Mercedes 560SEL 178k [COLOR="Red"]SOLD
1996 Chevrolet Suburban 140k
1977 Cadillac DeVille 98k
1996 Cadillac Fleetwood SS
1985 Mercedes 300SD 303k SOLD
2000 Corvette 27k SOLD

The best option is the six cylinder from the '86-'87 SDL's. It's a drop-in replacement.

Naturally, you could put the 617 in that vehicle, but, it's quite a bit of work and you'll get some rather poor performance. Additionally, the vehicle is effectively unsellable after you have done all the work. You'll need a transmission for the 617 as the existing trans is not compatible with it.

Thanks Brian,

Based on your advice I would plan to replace the 350sdl motor with a motor from a 300sdl. Do you have any sources for a decent low mileage motor or do you wait until one comes up or someone is parting one out?

Does it make sense to buy one with a damaged head and replace the head at the same time?

The 350 I am looking at was run without oil and ceased but it's a miracle it made it to over 150k anyway.

Thanks,

David


www.blackandwhitecookies.com

__________________
My Fleet

1987 Mercedes 560SEL 178k [COLOR="Red"]SOLD
1996 Chevrolet Suburban 140k
1977 Cadillac DeVille 98k
1996 Cadillac Fleetwood SS
1985 Mercedes 300SD 303k SOLD
2000 Corvette 27k SOLD

Take a couple of cam bearing caps off the 350 SDL head and see if oil starvation affected the head. If the caps are scored the head is probably junk because the bearings do not have replaceable bearing shells. If it looks pretty good then take it to a machine shop and have it evaluated. Then try to find a 300SDL with a cracked head you may be able to put a good motor together without spending a lot of money. The 350SDL head is a later version which does not crack. The vacuum pump from the 350SDL is the non exploding kind so you may be able to use it too.

I just replaced a warped, cracked head on a 300SDL with a new 22 head that I got from Metric. Total cost was $2,500 for a new head, new valves, new prechambers, gasket set and shipping. I spent another $500 for all new tappets and a new Vacuum pump. My car had been well maintained so the bottom end was in very good shape. The cam and injectors were good and the cylinders still had the factory crosshatch. The car is a real screamer now!

You are looking at around 20 hours of work and about $3,000 but if the rest of the car is in good condition you could have a very nice car when you are finished.

Remember that these cars can become money pits so be sure that the rest of the car is in very good condition before you get into it.

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Tom Hughes
St. Louis
84 300SD
92 300D
86 300SDL

The availability of the 3L 603 engine is spotty at best, due to the low quantity of vehicles available. You'd need to keep an eye on the larger recyclers and/or this and other forums. Expect to pay about $1500 for a decent one. Low mileage is very questionable, however.

If you find one, it will be very unlikely that the seller will admit to a cracked head because the value is reduced to almost nothing. However, if you do, it can be a benefit for you. However, the cost of a replacement head and all remaining work is about $3K. It's a rather large expense considering that it's still an engine with quite a few miles on it.

The 350 has a very good head that can be used on a future 3.0 engine, if you can get it at a good price.

and i dont see why the cam supports from the 603 3 liter couldnt be swapped over. but i am not really all that familiar with the 603 motor so there may be a reason.

the bottom ends are generally very robust on the 3 liter motors.

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.