Hello, I do not frequent this section very often but I have a good question.
I have a 1983 300td wagon that I want to install a 2.5l turbo motor into. I am a Mercedes technician and have done lots of fabricating.
Really the question is has anyone done anything like this before and what do you think I need to to the conversion. I understand that the 2.5 uses a vacuum operated waste gate and that the computer also controls the idle. Besides the computer and a couple of vacuum transducers, what else will I need.
My long term plan is to install an overdrive transmission on the back of the 2.5 and have overdrive with lock up. I was thinking that I should be able to get pretty fantastic mileage.
Also I was curious if anyone has looked into rack and pinion steering on the 123 chassis. I was going to go after this at the same time.
Just looking for some positive input, thanks.

Get a conventional pressure wastegate actuator so you don't have to deal with the controller and other vacuum devices. You still need the controller (EDS) for electronic idle control. Or set base idle high enough that you don't need any electronics.

How do you plan to keep SLS with the 602? Will a tandem pump from a 603 fit a 602?

From my research, you should be able to attach a 722.5 transmission (5-speed AT out of a 90-96 up 300SL/SL320, 300SE/S320) which without electronics will skip 1:1 fourth gear and go straight to overdrive. There might be a away to keep fourth gear. There's a fellow in the Seattle area who makes standalone controllers to adapt a 722.6 (5-speed AT from 97) to older MBs. In general, the OM602 bell housing pattern is the same as the M104 and OM606 pattern, and both the latter engines came with 5-speed ATs from 97.

Rack and pinion steering will be a big job because the knuckles have tie rod attach points towards the firewall where there's nowhere to attach the rack. You'll need custom knuckles to work with a rack ahead of the front axle.

Sixto
87 300D

People have done it before.

Rack and pinion: http://www.peachparts.com/shopforum/showthread.php3?threadid=79286

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Will the stock motor mounts for the 2.5 fit a W123?

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

I am looking into these details. I like the idea of using the 603 tandem pump for the sls.
I am going to use the 722.6 as I am the guy from Seattle.
As far as using the stock boost control, what would be the problem if I had the computer? Is the boost control problematic or just a preference?
I am debating on buying a motor from the local salvage yard or buying a complete car. If the engine can work well without the computer then that would be interesting to me.

A 722.6 attached to a OM602? Wow....that trans will last forever!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

EDS is not particularly problematic but it doesn't have modern OBD so diagnosing a no boost situation can be tedious. Since you're the fellow in Seattle, you're lucky to know gsxr who has particular expertise in 602s as well as 603s. Heck, if you've figured out 722.6 electronics, 602 electronics will be cake. But note, the suggestion isn't as much a customization as reverting boost control to what came in the 87 190D 2.5 turbo and early Euro spec 250D/TD turbos.

As for the mounts, I'd look into using the arms from a 126 with 603 since 126s use the same rubber mount/separate damper system as the 123. The 124 uses fluid filled mounts. Might be the same amount of work either way but I'd spend some time exploring the 126 arms hypothesis.

Sixto
87 300D

for the 722.6 you need the pcm from a w210 since the shift points are computer controlled.

in regards to the guy who put the 602 in the w123 , rack n pinon steering is a down grade....

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Thanks the w126 with the 603 arms are a good idea if I need to change them. I do not know yet. Also, I understand that the boost control is easier to diagnose. I just have not had that many problems with the stock system other than the vacuum transducers going bad. But I do not work on a lot of them.
I will keep this in mind though. I have not decided which way to go yet. It will mostly depend on how difficult either direction is.

In response to the control unit issue on the last post. I use a programable stand alone transmission control unit to run the 722.6. The tcu simply needs power and ground and a speed sensor and a throttle position sensor to operate. I use map load on my other car for more control but I have not tried this on a diesel yet. I may use an air mass sensor to calculate load on the diesel.
The point of the project is to keep my wagon and make sort of a modern driver out of it. I love the style of the w213 wagon and mine is a european model with the small bumpers and a factory trailer hitch if you can believe that. I just want to get excellent fuel mileage with the more efficient engine and the overdrive. I see no reason that I can not get high 30's in the fuel mileage and maybe a little better.
Again thanks for the positive input.

These Diesels have a vacuum controller that simulates manifold vacuum as a signal to the 722.3/4 modulator. Rube Goldberg might run this signal through a common MAP sensor to provide a throttle position signal.

Sixto
87 300D

Except that it may not be physically possible. The W123 is heavy, has poor aerodynamics and an automatic always sucks the efficiency out of an engine, even with OD and lockup clutch. A 190D 2.5 will barely see high 30's with a manual.

Thats the thing. The 190 is no spring chicken either. I have checked the weight of many vehicles and the smaller cars never weight more than 200 lbs less than the midsize ones. A 190 may be in the 3500lb range and the e-class will be in the 3700lb range. Just not enough to make a lot of difference. Especially not on the highway. Which is were the overdrive and torque converter really shine. It is not any different than many of you putting in 2.47 gears to increase the mileage. I just want to be able to accelerate from a stop also. Besides, once the torque converter locks up it is basically the same as a stick shift. The only power loss is from the hydraulic pump.
Also, correct me if I am wrong, but the 190d stick as in most mercedes is not an overdrive unit.
I know I might be shooting high but I still think that it should be possible.

Some 2.2's had a 4-speed but the 2.5 should have a 5-speed with a ~0.86 OD.

Well I purchased a 2.5 turbo from a 93 300d today. I got a tandem pump for the sls that bolts right on. I will be starting in a couple of weeks on the transplant. If everything goes smoothly then I will be selling my 617 turbo motor. It is a euro model with no egr and the adj waste gate. Any idea what it is worth?

According to the data from the identification plate on my 190D, its curb weight is only 2775 lbs.

The '84 sales brochure I have says "Top gear in the five-speed manual gearbox functions as an overdrive for quieter, more economical high-speed cruising". The ratios are: I: 4.23; II. 2.36; III: 1.49; IV: 1.0; V: 0.84; R: 4.63

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1989 250TD Wagon 5-speed, 160,000mi ::: Dark gray metallic / black cloth
1984 190D-2.2 5-speed, 287,000mi ::: Silver-blue metallic / black MB-tex ::: SOLD