My father is attempting to install a remanufactured 84 300 Turbo Diesel engine and transmission in his old ’81 300D. It’s a grand undertaking to be sure, but he has some questions, so I thought I’d post them here to see if there are any experts that can give him some advice. He believes the swap will be pretty straightforward, except for the following four items:


1. If you examine the first picture attached, you’ll see a “Turbo Pressure Switch”, labeled as item number 12. Since there is obviously no wiring for this setup in the 81, my father would like to know how to properly wire and fuse this item.

2. If you examine picture number 2, item number 7 is called a “Switch Over Valve”. There was no such animal on the ’81, so how exactly it will be hooked up properly on the ’81 is a mystery. It can’t be seen in the scanned picture, but the connections on the valve show the left connection heading “To Manifold” and the right one “To Aneroid Compensator”. I have no idea what an Aneroid Compensator is. Maybe you kind folks can help.


3. Looking at picture 3, you can see that the “Transmission Inhibitor Switch” is round. On my father’s 81, it is rectangular. The problem is this; on the reman 84 tranny the switch is round. Can the wires be simply spliced from the old switch and hooked to the new round one?


4. On the older 81, apparently there is a vent pipe that runs from the air cleaner to the oil pan, On the newer engine, it is eliminated. Is it necessary to hook this up? Does he need an air cleaner system specifically for the 84, or will the 81 work by simply closing of the air cleaner’s connection to the vent pipe?

Lots of questions, I know, but I hope you can help. If not, can you point me to any other MB forums which might be able to be of assistance? Thanks again.

PS Any other tips on this conversion would be gladly appreciated.

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