engine swap on s III

[Tim Smith]

One thing that's nice about them is they are a "high-speed" diesel so you don't run into the gearing problems with them as you do slower turning engines.

So Jim, you don't have RPM problems trying to keep freeway speeds? I assume you have an overdrive fitted but I'm not sure what the normal high speed engine rpm should be for these old MB diesel engines.

PS: I'm hoping to fit my own '85 617 Turbo motor into a 109 project one day but have been thinking about the gearing issues. I have no idea what my 2.25 is reving at at about 65 mph. Nor do I know what the MB motor likes to run at, as my rpm gage is broke in that car too.

[Mercedesrover]

The truck will run at 65 without worry. It's probably happier at 60 but I've run at 70 (on a good day and a tail wind) and didn't worry about it. The tranny is screaming at those speeds more than the engine for sure.

And yes, I'm running a Roverdrive and 4:56 Toyota gears. (Very close to the original 4:70)

The 240D manual-tranny cars were built with 3:46 gears, a 1:1 final drive in the tranny and much smaller tires than we run, and though I've never done the calculations, the gearing at the road is probably pretty close.

Jim

[Alacrity]

Thanks Alac! Good stuff

You wouldn't happen to know if any of the turbo 617 engine versions had fewer or less obtrusive hangy down parts on the lower right side of the engine would you? I have long thought a 617 might be a good swap into a Series rig if they had the correct shaped pan and a lot less stuff sitting low on the engine's right side.

Jim can answer those questions better than I - IIRC he has both a 616 and 617 in possession and experience in the swap. Im a W123 fan not a MB diesel in a Rover guy. There are useful physical difference between various engines - early vs late, and what type of vehicle donated. IIRC there are some early 616 (not necessarily all early) that dont require the remote oil filter and better exhaust placement. Im pretty sure all the turbos foul on the frame.

I can answer the rpm question - MB 240Ds. Stock 240D runs approx 2400 @ 55, 3000 @ 65, 3400 @ 70, 4000 @ 80mph. Cars were marketed during the 55mph 70's/80s - as efficiency minded chariots. So I imagine peak efficiency (and I would have thought torque) is somewhere around 2400 rpm. They handle the current 65/70 speeds fine - but people complain about the mileage. Above 3500rpm the 240D (616) gets busy. 300D and 300D Turbos have about the same sweet spot - they just perfom better all around. Gearing in a ROver is a different matter (ETA - and one Jim just answered.)

Dyno info 300D Turbo (617.952)
http://berryhillfarm.us/benz_stuff/Dyno/dynorevs.jpg
http://berryhillfarm.us/benz_stuff/Dyno/dynochart.jpg

The common (and factory) claim of peak torque at 2400 isnt seen here. Ive heard many people claim all these engines are gutless, esp the 240D - little low end torque - even compared with the Rover 2.25. Ive got a rebuilt 2.25 coming - I need to dyno it. Comparing my 2.25 109 to various W123 oil burners Ive piloted, even turbos - it does seem a bit more motivated off the line. Likely due to gearing and petrols ability to rev.

Original ratios for US 240D were 3.69 (Euros got 3.92, optional 4.36), weighs about 3050 lbs - in the ballpark for an 88. 300D about 100 lbs heavier - the Turbos about 500 lbs above the 240D. 300D is 3.46. 300DT got 3.07 (-'84) and 2.88 (85). Explains less performance gain than expected I observed above.

I have the transmission ratios somewhere if they're needed.

Luck
Alac

[KingSlug]

Originally Posted by TeriAnn
Thanks Alac! Good stuff

You wouldn't happen to know if any of the turbo 617 engine versions had fewer or less obtrusive hangy down parts on the lower right side of the engine would you? I have long thought a 617 might be a good swap into a Series rig if they had the correct shaped pan and a lot less stuff sitting low on the engine's right side.

TeriAnn

The 240D oil pan sits pretty much center line on the engine, although the oil pick-up sits on the RHS, I believe Jim did a little shaving to the oil pan. The 300D pan is similar, but the pickup is centered in the pan, so sculpting the pan wouldnt be a big worry. The 240/300GD oil pans, upper oil pan and oil pumps are deeper (bigger); I havent installed them but by looking at them there isnt too much difference. I have mocked up plans and designs of reversing the upper and lower oil pans and cutting/adapting then re-routing the oil pickup to the rear of the engine a'la what Toyota did with some of their earlier 4x4 engines, but am stopped on the project currently.

[om617]

TeriAnn,
I am in the process of fitting an OM617 in a 109SW. When I figure out the digital camera and have some photos, I will send some to you. Until then, I am working out the kinks of fitment. The oil pan issue appears to be resolved with extended shackles and moderate trimming of the lower sheet metal oil pan. As far as the turbo etc, I still am working on that one but it appears that it is going to work. The radiator placement is being jostled around and I have not fully decided whether to move the front crossmember or go with a crossflow. Perhaps a little of both in order to keep the stock Series IIA look. Last but not least comes the gearing/overdrive. Any thoughts? Don