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Discussion Starter #1 (Edited)
Well, my pal Jim had his 91 164L compressor throw a rod and exploded a clutch bearing and melted clutch coil after he had a local shop near him convert it to 134a. Not sure whether conversion had anything to do with it but I shipped him another compressor with new shaft seal and clutch bearing as his old assembly was pretty wasted.

Yesterday he drove in for a visit so we changed out receiver dryer and expansion valve and charged up system with Freon, oil and dye and he drove 330 miles back home in cool comfort.

Here are some picture of his carcass we disassembled for show and tell. Threw away metal clutch coil and he took piston set home for a desk paperweight.

Note: SD-709 has seven pistons so the 7 and .09 cu in displacement so the 09 in part number.

Takes a few pieces to build a car and the parts that go into it doesn't it?
 

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Steve, you know what my question is going to be. :D What oil did they use in the conversion, did they label the car? Very interesting what is inside a 709.
Charles
 

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Discussion Starter #3 (Edited)
Steve, you know what my question is going to be. :D What oil did they use in the conversion, did they label the car? Very interesting what is inside a 709.
Charles

Have no idea, not sure they even put any oil in it as there wasn't any in compressor just an oily film, so that may have been the problem. I used - you guessed it - POE aka Ester Oil. They didn't change receiver dryer or expansion valve either.
 

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Have no idea, not sure they even put any oil in it as there wasn't any in compressor just an oily film, so that may have been the problem. I used - you guessed it - POE aka Ester Oil. They didn't change receiver dryer or expansion valve either.
Interesting stuff. Looks like you could make some kind of engine out of that compressor, doesn't it. Next thing, we'll have pics of the Binford-9000 Super Impact Gun with 7-piston air motor...

I have a friend who is an air conditioning specialist. He did a 'cheap' job on my last 164 for me. I did ask him to fix it, since it wasn't cooling too well, and he chose to suck out the R12 and convert it to R134a, if 'convert' is the word. In my mind he did the job much too cheap. I asked him to at least replace receiver/drier and change expansion valve, but he did neither! :eek: Unsurprisingly it stopped cooling completely a few weeks later, and when we put the gauges on, it still had a full charge. My guess was that old oil reacted with the PAG oil that he added, to make a gunky mixture that clogged the expansion valve. He cleaned out the latter and it seemed to work again, but never very well.

My 164 (Singapore-spec) had a single-speed radiator fan that only cut in at high a/c pressure, so I wired a relay to run it whenever compressor was 'on'. That seemed to help a bit. (At least my 164 had a heater matrix - someone told me about an ex-Singapore Mercedes that never actually had a heater fitted...)

I don't have much experience but I really can't understand the shortcuts that some 'professionals' take with a/c. I think your choice of ester oil (rather than PAG) is a good one, since without a total stripdown I don't see how the system can be made clean enough to accept the new (PAG) oil. I also suspect that it is worth changing the expansion valve to an R134a type?

Cheers,
-Alex
 

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Discussion Starter #6
There is an oil fill/drain plug (to drain it it has to be out of car to be able to turn it upside down, to fill it on car the alternator has to be out of the way).

I usually drain and measure old oil and then fill compressor on work bench with syringe or small funnel and then to add extra oil later on if needed when charging/recharging you need 2oz oil charge can or oil/freon cans.

When I have my hobby shop do it they have special fitting and syringe they put it and dye in through high pressure service port. I use them for R12 as they have fancy recovery and service machine.

If you also add dye leak check to low pressure side where you put canned freon in as a gas do it after system charged.
 

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Sorry to dredge up an old post but are these compressors normally hard to turn? I have had a junk yard compressor (SD508) on my car for a year or so but never got the system filled. When installed I don't remember it being hard to turn.

Now it is stiff but can be turned with a ratchet.

The manual from the Sanden website doesn't delve into the piston end of the pump. Could they be disassembled and cleaned in your view?

Failing that I also have a Seiko-Seiki pump which appears essentially the same and turns much easier.

This is all for a 75 (Milano) and unfortunately new is out of budget.
 

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Hi,

Compressor shaft should be more or less easy to turn. It is harder to turn the shaft right after A/C operation since the pressure is high but after some mins that the pressure equalises between the high and the low ports then it is far easier to turn it by hand.

A key factor you mentioned is that the compressor comes out of a scrapyard. In case the service ports were open to atmospheric air then for sure oil absorb moisture and formed a thick, honey like substance in the internal parts of the compressor.

You have two options.

1) Drain the old oil and flush the internals with new oil several times. Charge with freon and check if the compressor has oil leaks during operation.
2) Rebuilt the the compressor by renewing head gaskets and front shaft seals. It is a tricky job but can be done with attention and patience.

Regards
 

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Discussion Starter #9 (Edited)
I tested out Goggle Search function using words SD-709 compressor and as Alex said this post comes up close to top. Interesting wonder how google does that?

Thought this Sanden manual that came up near first place has nice info, too: http://www.sanden.com/images/SD_Service_Guide_Rev.2.pdf
 

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I tested out Goggle Search function using words SD-709 compressor and as Alex said this post comes up close to top. Interesting wonder how google does that?
Amazingly, you only need the word "SD-709". Given there are dozens of vehicles that use this compressor type, and hundreds of other unrelated contexts for "SD-709" (medical, chemical, etc.), I thought it was pretty incredible too. Just goes to show how this forum is special and how these threads are valuable.

Over the years I have sometimes tried a web search for some specific topic and turned up my own forum posts on the subject made years before. It feels like I'm being caught talking to myself.

On a related note, the search feature of this forum has a 'search cloud' of frequently-used search words and I see that "Alex" is the most commonly-searched word. I assume that relates to Alex Csank rather than myself!

-Alex
 
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