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Old 11-19-2013, 05:21 AM
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Hit Man X Hit Man X is offline
Join Date: Sep 2004
Posts: 9,087
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Yes, by all means flush the thing. No telling what oil is actually in there now, you answered this yourself once you discovered the seller was full of it. TXV on a W126 is not that bad, it is a pain but doable within an hour if you have the proper tools. Crows feet and line wrenches that fit a ratchet. Take your time reinstalling it and do not cross thread the fittings. You need to have them all threaded a few turns before tightening it or it will never line up.

I would not use 134A, but it is your car. R12 cools far better in these. I suppose if you went for a parallel flow condenser you would have decent vent temps. No experience there, sorry.

Oil goes in before the charge. Mineral is R12 only (BTW, I have not bought a 'new' compressor recently that was full of mineral), PAG 134A only, Ester seems to go both ways just fine...Esther is a woman's name.

Verify all the vacuum pods work, the three behind glove box can be swapped in about 30min and cause many of the issues such as defrost only, poor vent temps due to no recirculated air, etc.

Later SDs had a better condenser, smaller water pump pulley, and upgraded fans (clutched and aux)...these all improve vent temps at low speeds/idle. BTW, the M116/7 fan with clutch off a 420/560 fits, should be the same off a 380/500... those fans move way more air and probably cheaper than finding a late SD fan with clutch.

I highly recommend dumping that GM R4 compressor and going with a Sanden conversion. Best thing I ever did for my SD. It was $200 plus the cost of compressor and building a few hoses.

If you are uncertain of the condition of your R4, do not take the chance. Made that mistake on the 560 with the Denso on there as it worked, rebuilt it all, etc. Compressor body leaks. It is the original from '91 though, so no one to blame but me.
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
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