My New Odd Combination-Motor, Trans, Body--What should I hook up? - PeachParts Mercedes-Benz Forum

Graplr · #1 09-02-2008, 10:57 PM

My 1984 300SD (126)'s engine and transmission konked out about a month ago. It was my fault. I changed the tranny filter and gasket and must have over torqued the bolts and broke the gasket. I then leak fluid and my tranny started slipping. Eventually it wouldn't shift up and I tried to make it home about 5 miles running in first gear at over 4000rpm constantly perhaps even 5000 rpm. The previous owners had taken off the switch over valve from the turbo to the ALDA. The engine blew. There was a small fire on top of the turbo. Perhaps just the turbo blew but that is another discussion. I'll investigate it later after I get the engine out.

I purchased a 1980 300SD (116) with the floor rusted through but a good tranny and motor. The person I bought it from had only had it a year and barely had driven it. He was told that right before he bought it, it had a new (well not new, but from a different car) put in. The engine supposedly had 130k on it but there was no documentation so I can't verify that. (I got it cheap so it doesn't matter!!

)

Before I bought it I verified that it was a 617 (and of course that it ran well) but I couldn't tell specifically if it was a 950,951, of 952. I assumed it was a 950.

The transmission was original from the 116.

I have the engine and transmission out of the 116 and have pulled most of the parts out of the engine bay. So tonight I decided to see if I could find any serial numbers. I of course found it behind the oil filter.... Low and behold it is a 617.952! Here is the full engine serial if anyone can shed any more light- 617 952 12 022 466

So that means I will have a 300D 123 engine, with a 300SD 116 transmission, in a 300SD 126 body! I wonder if anyone has had that combination before!

I just ordered a bunch of gaskets and such today to redo stuff while I have the engine out. I doubt I will get the parts by this weekend so I probably won't get the engine installed for another couple weeks.

Here are my main questions.

What makes the speedometer work?
What makes the odometer work?
What makes the tach work?

I am trying to figure out how to get everything to read correctly on my 'new' car.

In the 'about 200 miles' I drove the 116 I noticed the speedometer worked but was not accurate. The tach worked only for a few seconds. And the odometer did not work at all. On my 126 all 3 worked. I am trying to figure out which cluster to use.

Here is what I know-
It has a mechanical oil gauge on the 952. My cluster is set up for electrical oil gauge. Perhaps I can put my electrical oil gauge sender on the 952 block??

How about the speedometer? Do I use the speedometer cable from the transmission? If so won't I need the 116 speedometer? Since it was off in the 116 won't it be off in the 126 as well?

What do I need to make the odometer work?

What do I need to make the tach work? Is it the TDS transmitter that comes out of the front of the engine?

I know, lots of questions. But I figured most people would be interested in this project as if it is not the first time this combination has been used, it is at least rare.

Thanks,
-Ryan

*EDIT* Here is something I just thought of...how can it be a 617.952 engine if the a/c compressor is located on the driver's side of the block? Is this possible? Are the TDs compressor placement different from the Ds compressor placement? I'm positive the block says 952. The serial number above is correct. Perhaps someone can shed some light on this impass. I'll double check the serial number in the morning, but unless I'm halucinating it is a 952 stamp.

Graplr · #2 09-03-2008, 11:18 AM

Well obviously that post was too long...sorry. Let me summarize.

84 300SD 126 body
82-85 300D 123 engine (engine serial number 617 952 12 022 466- Can anyone identify the year based on this number?)
80 300SD 116 transmission

I know I can get everything to bolt up. I am wondering how to make everything work.
Speedometer
Will I have to put the mechanical speedometer from the 116 cluster into the car's cluster?
Odometer
If I change out the speedometer can I leave the odometer in or do I have to change that too?
Tach
Does it matter if I leave it in or change this out?

Odd things I noticed
1-Speedometer read low in the few hundred miles I drove the 116 with the 123 engine and original tranny. Wonder if they put a different rear diff in? Or what else would cause the speedometer to read low? It said I was going 60-65 when i was really going 75 or so.
2-Tach didn't work
3-Odometer didn't work
4-Compressor was located on driver's side of engine block. The correct bracket is there as well. Is it possible the PO bolted a compressor bracket onto that side?
5-The battery wouldn't hold a charge. The battery was good as I put in a known working one. There was only one belt on the alternator and it appeared loose. Where is the alternator located on the 952 engines?

Thanks,
-Ryan

Jeremy5848 · #3 09-03-2008, 11:25 AM

3. Odometer -- if the speedo works (accurate or not) and the odo doesn't, the odo is broken inside, perhaps one of the plastic gears is slipping on one of the metal shafts. You can fix it yourself or send the unit out to a shop.

4. Compressor -- My '85 (617.952) has the compressor on the driver's side.

5. Alternator -- Ditto, right (passenger) side.

Your big challenge may be attaching the transmission to the engine -- others will have to advise, I've never done it.

Jeremy

Graplr · #4 09-03-2008, 11:38 AM

Quote:

Originally Posted by Jeremy5848

3. Odometer -- if the speedo works (accurate or not) and the odo doesn't, the odo is broken inside, perhaps one of the plastic gears is slipping on one of the metal shafts. You can fix it yourself or send the unit out to a shop.

4. Compressor -- My '85 (617.952) has the compressor on the driver's side.

5. Alternator -- Ditto, right (passenger) side.

Your big challenge may be attaching the transmission to the engine -- others will have to advise, I've never done it.

Jeremy

Wow, thanks for the info Jeremy.
3- Thats good to know that something with the odo (gears) is inoperable. Anynone shed any light on the speed being off?

4- Thanks. I assumed all 952s had the compressor on the left (driver's) side.

5- I only asked because I thought the compressor was supposed to go there and that may have been the problem with it not charging. It appears that it may be because of only one belt and or a loose belt.

Fortunately the PO already attached the tranny to the engine and I have both out and still bolted together. I guess I am just assuming it is the 116 tranny since it has a square tranny pan. I'll have to look at the serial number.

Jeremy, any chance I can get you to look at your engine serial number when every you get a chance and let me know what it is so I can compare it to mine? It is on the block under the #5 cylinder behind the oil filter housing.

Thanks!
-Ryan

vstech · #5 09-03-2008, 11:44 AM

you might be able to swap over the tailshaft from the original tranny onto the 116 tranny. I do not know if they will swap, but that way your electronic speedo will still work. otherwise, your'e going to have to get a manual to electronic speedo gadget for around 100.00, or route a mechanical cable up into the dash, and try and make a manual speedo fit... not very simple.
pm Brian Carlton, he told me where to find one...

Graplr · #6 09-03-2008, 12:04 PM

Quote:

Originally Posted by vstech

you might be able to swap over the tailshaft from the original tranny onto the 116 tranny. I do not know if they will swap, but that way your electronic speedo will still work. otherwise, your'e going to have to get a manual to electronic speedo gadget for around 100.00, or route a mechanical cable up into the dash, and try and make a manual speedo fit... not very simple.
pm Brian Carlton, he told me where to find one...

Thanks. I didn't think about trying to get the electronic tailshaft off the 126 tranny. I am pulling the bad engine and tranny from the 126 on Friday and will have both engines sitting next to each. I will see if I can get it to work. If not I will probably see if I can get the mechanical speedo to fit. Then if not I will pm Brian. Thanks for the info.
-Ryan