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Discussion Starter #1
Well I think I found a replacement motor for my 1981 300d in a local salvage yard. It is in a 1980 SD with 180k miles on it. Just making sure that will work in my 1981 300d, right?
 

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Will it work? Yes.

Will it be a drop in fit? No.

The SD will have a turbo engine, which you'll like. It's a good upgrade, and if it's a good engine, it's worth doing the work to fit it to your car.

The cooling system will be different- the turbo engine has a different radiator and surge tank.

The 'arms' which attach the engine to the engine mounts will need to be transferred from your engine to the replacement.

I don't know on the 80 SD, but if it has an electronic oil pressure sensor, you'll need to transfer the oil filter housing from your old engine to the replacement. If the W116 has a mechanical gauge, then it will be the same.

Linkages, etc, will likely be somewhat different.

There is a switchover valve which needs a ground and key power to function. It is installed in the ALDA line.

The exhaust from the turbo engine is going to be different. You must use a turbo exhaust. I would look for a donor W123 turbo car to get the necessary cooling system and exhaust parts. Also, turbo 300D's have an exhaust shield which you'd probably want to install.

You'll find a few other things, no doubt, but it'll work with some careful planning.
 

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This 1980 SD has a turbo motor. The 1981 D has a non-turbo motor. The SD turbo motor will work, you'll need to swap a few items such as the motor mount arms, a/c lines and other items like stated above. Oil filter housing is mechanical, so the gauges would be compatible. The rear differential gearing would be kind of high for the turbo motor at cruising speeds. But certainly would make stand still acceleration much more faster.



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Discussion Starter #4
Yessssss

And with those two replies, my friends, you see why I love being a member of this user group.
 

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Discussion Starter #5
One more question

I forgot to ask, will my 300d head bolt up correctly to the 300sd short block if I wanted to avoid the exhaust manifold hassles?
 

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I forgot to ask, will my 300d head bolt up correctly to the 300sd short block if I wanted to avoid the exhaust manifold hassles?
Not sure what your asking? But I gather you want to make the SD engine into a non-turbo? Not worth the time to do it. Best to spend the time and get the exhaust situated, like getting the stock flex down pipe and then get the rest of the exhaust from a donor or fabricate one.


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Can you replace the turbo intake and exhaust manifold with the non-turbo ones? The turbo will be removed, that is a drawback, but there are less modifications.
 

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Discussion Starter #8
Turbo to non

Yeah that was my question, at the sake of sounding stupid, which I am failing at miserably here already in this post. I was wondering if the head exhaust ports were in the same location as to just go non turbo. I would like to just put my good head off my 300d on to the good short block of the 300sd motor. I just wasn't sure if that was possible or not.
 

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The head casting on a non turbo OM617 is the same as the turbo one. The turbo has different valves and a higher lift cam.

I don't think you'll have trouble fitting the non turbo manifolds. However you've got a oil turbo supply and drain system to contend with - I guess you'd be better off just looping it around the engine. I don't like the idea of blocking stuff off if you don't know how it will behave...

I would however consider swapping the IP for the non turbo one - I'm not sure if using the turbo only IP would be a problem or not - perhaps it will give too little fuel? Anyway it is a pump designed for the turbo - it isn't used on any non-turbo OM617...

As for the compression ratio - the difference between the turbo and non turbo OM617 is small.

I must say you're nuts though - most people want more power not less.
 

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The head casting on a non turbo OM617 is the same as the turbo one. The turbo has different valves and a higher lift cam.

I don't think you'll have trouble fitting the non turbo manifolds. However you've got a oil turbo supply and drain system to contend with - I guess you'd be better off just looping it around the engine. I don't like the idea of blocking stuff off if you don't know how it will behave...

I would however consider swapping the IP for the non turbo one - I'm not sure if using the turbo only IP would be a problem or not - perhaps it will give too little fuel? Anyway it is a pump designed for the turbo - it isn't used on any non-turbo OM617...

As for the compression ratio - the difference between the turbo and non turbo OM617 is small.

I must say you're nuts though - most people want more power not less.
If the turbo IP doesn't receive a boost signal via the ALDA, it will not deliver more fuel.

Not using the turbo on a turbo engine means less wear on the engine, longevity will improve.
 

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Yeah that was my question, at the sake of sounding stupid, which I am failing at miserably here already in this post. I was wondering if the head exhaust ports were in the same location as to just go non turbo. I would like to just put my good head off my 300d on to the good short block of the 300sd motor. I just wasn't sure if that was possible or not.
The head casting on a non turbo OM617 is the same as the turbo one. The turbo has different valves and a higher lift cam.

I must say you're nuts though - most people want more power not less.
Yeah! Give that turbo engine to me! You can have the underpowered N/A engine powering Donkey.:D

Does the turbo valve timing also differ from the non-turbo? Maybe it could improve the N/A outputs? Maybe the turbo could just be removed from the turbodiesel, and the N/A piping fitted? Sounds like a lot less work to me.
 

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Maybe the turbo could just be removed from the turbodiesel, and the N/A piping fitted? Sounds like a lot less work to me.
That was what I suggested, you are left with the oil line to the turbo, as Army mentioned. That has to be blocked or connected directly to the turbo oil return line.
 

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Discussion Starter #13
I think your right

I think it's better for me to find the turbo parts needed and go that direction, as opposed to the same amount of hassle to avoid that nice extra hp. Thanks guys for all your help.
 

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That was what I suggested, you are left with the oil line to the turbo, as Army mentioned. That has to be blocked or connected directly to the turbo oil return line.
How hard could that be?

Not that we ever had turbodiesels here. Nuts...
 

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I have a question about converting the turbo engine over to N/A - doesn't the turbo engine have a lower compression ratio than the N/A engine (this is the case w/ many other mfgr's...not sure about MB)?

If the turbo engine has a lower compression ratio, converting it to N/A by means of installing the N/A intake/exhaust could result in worse performance than if you went with a N/A engine to begin with...
 

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Nope: N/A CR =21.5

Turco CR = 22.0

Also: N/A Comp Pressure = 2400kPa
Turbo Comp Pressure = 3000 kPa
 

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Then I think it's time I start doubting my sources.

Maybe the car I'm driving isn't a W123 at all. Maybe it isn't even a MB.

Curse you, Haynes! Curse you, Automotive Service Directory!

:D
 

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Then I think it's time I start doubting my sources.

Maybe the car I'm driving isn't a W123 at all. Maybe it isn't even a MB.

Curse you, Haynes! Curse you, Automotive Service Directory!

:D
Haynes and Ciltons are the WORST auto books around UNLESS you have a NON US print.


Say you got a Ciltons UK version book. Totally different info, its like they want americans to make mistakes LOL.

BTW not knocking YOUR knowledge of your car or how to make repairs just saying you can find better stuff online for free than with those flavor or work manuals.
 
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