The AC in my 85 300D has been working well all summer since I added R134 to it this spring, until yesterday, when I did not feel any cool air coming out of the vents. Opened the hood and saw smoke coming from the compressor clutch, which was engaging and disengaging.

I will try spraying some brake clean on the friction surfaces and then a clutch gap adjustment if that doesn't help. Has anyone done a gap adjustment recently and can go over the procedure and tools needed? I played around disassembling an R4 a few years ago but can't remember an details.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Does this refresh your memory?

dissembling R4 compressor

another one

R4 compressor pics


Charlie


sent from my pos computer

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

When that happened to my car, the compressor was the problem. Happened 3 times to various degrees! Last time to cut belt because compressor seized. Still that way

Hope you have better luck.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Yes it does Charlie. Thanks for digging it up!

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Do you know why yours seized?

I measured the gap and it was within spec at around 0.53 mm. I noticed a slight film of oil on the outside of the clutch and sprayed Brake clean into the gap with my flex wand and blew it out with compressed air. Repeated that a few times to be sure it's clean. So far so good, clutch engages/does not slip, no more smoke and AC works fine again. Hope it stays that way.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The symptoms you describe would indicate a leaking front seal - very common on R4's (BTW that's where your refrigerant is leaking).

I will keep an eye on it and see if the oil film returns.

This video should help if I need to reseal.
https://www.youtube.com/watch?v=vImsu-D_Qnk

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

R4 reseal kits available from:
GM R4 Compressors - Century Auto Air

Making the case puller shown in this video looks pretty easy..
https://www.youtube.com/watch?v=vImsu-D_Qnk

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I don't see how adjusting the gap would affect slippage much. The gap mainly just determines if the magnet can initally pull-in the clutch, but once touching it is mainly the electromagnet force * friction that keeps it from slipping. There would be slighly less spring force fighting it if you reduce the gap, but probably fairly negligible. The oil on your clutch plates is probably the culprit in the slipping, plus adds to the smoke as it fumes off.

I am glad you posted this. My 1985 car's AC clutch started smoking years ago. I assumed the compressor had seized, but later found I could turn it easily. You now make me suspect it was an "oil on clutch" issue. I have a Sanden on there now, but kept that R4 and still use an R4 on my 1984.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I agree clutch gap would not affect slipping much. It was easy enough to check though.

I remember reading the R4 (and most AC compressors) have a built in slow leak via the shaft seals to lubricate them. Would this be true of my clutch shaft seal? I have not noticed any decrease in AC performance so far.

How is the performance between the R4 and Sanden in your 84 and 85?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Not really - nprobably lost refrigerant and oil. After I cut the belt, I took it to a local shop. They tried installing new belts and it was seized enough engine would not run. They cut the new belts!

I have tried turning by hand and compressor won't turn. There is also no refrigerant pressure, so I suspect I lost compressor seal?

I now ride with windows down in hot weather. Only one of our 4 Benzes has working A/C

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5