Did you try spraying brake cleaner into the clutch gap to degrease it? My clutch was smoking and cutting in and out a while back but did not squeal or make any noise. Upon inspection, it was all oily on the outside from a previous bad valve cover oil leak (not from refrigerant leak). I sprayed the gap with brake clean = no more smoke or cutting in / out of the clutch.

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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

If the brake cleaner question was oriented at me, no I didn't. It costs 50$ or so each time I fill up the system (recovery cost, r134a, receiver drier, o rings) - vs ~200$ for the new r4 compressor. I tend to move towards replacing anything suspect instead of wasting time & money and hoping that the old parts will work - hence my 100% complete system rebuild - well, 99% rebuild. I will have exactly two original components in the refrigerant loop, both of the metal fittings that connect to the TXV.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

It was directed at you. So you did not do any testing or diagnosis to learn what caused the squeal? I fixed the smoking clutch with 1/10 can of brake clean. Are you saying I should have replaced the R4 instead?

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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'm saying I had a system that wouldn't take a charge and was making horrible noises. I had absolutely no idea when the compressor had been replaced (if ever). The only way I could diagnose the horrible noises would be to charge the system to reproduce them. I made the call to replace the compressor (Which ultimately didn't go so well, since the replacement failed even worse) because it made financial and labor-cost sense to me. In my case, it made sense to replace the unknown part with a hopefully good part. That didn't work so well, but there's no way I could have known that the new compressor would fail so rapidly (I've since returned that compressor). I've spent a lot of time repairing parts on this car to save money vs buying new parts, including parts that are not supposed to be repairable, and really I just wanted to get the car back on the road in a timely fashion (any time I'm not driving the car, it's wasting money since I keep it insured).

I'm definitely not saying you should or should not have done anything. In fact, I admire that you've gone through so much work to test every component of your system, and I'm looking forward to comparing the results of my "replace ALL the things" methodology vs your "test everything" methodology.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Returning a part damaged by improper instillation is unethical.

Over on tech section, there is a guy that returns properly working parts once a year under the lifetime warranty. This is unethical too.


In another thread:
Compressor failed spectacularly

Post 22


07-25-2016, 06:23 PM
Demothen is offline
Registered User

Join Date: Nov 2015
Posts: 413
Well, looks like this was my fault after all. Apparently I forgot to do a final torque on at least two the compressor bracket bolts, or they loosened on their own. Most likely I forgot to torque them. I am not going to return the compressor now since this was clearly my fault.

And this is why I used touch up paint to mark suspension bolts after torqueing them. Plus it easily indicates if they have backed out for later inspections.

After actually pulling the part, it was clear that not tightening those bolts was not responsible for this. See also: this thread. Furthermore, I told the parts store exacty what had happened.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

For me, the testing/ diagnosing of the components is to gain knowledge. By just replacing the entire system, you haven't learned anything and will make the same mistake(s) next time.

__________________
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

Heh. I have learned a lot like "tighten ALL the bolts" and "replace anything that looks faulty"...
I do plan on pulling the original r4 apart once I get some time. Right now I am focused on getting the car back on the road ASAP

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Since it got buried...

I ask because if it was, that could give a clue as to why the new one popped.

-Rog

Who are you asking, Rog--me or Demothen? In my case, when I asked my mechanic to look for leaks and recharge the system, he said the original (bad) compressor was "puking" fluid (a/c oil/refrigerant) out of the front of it...whatever that means.

R12 vent temp 85 300D 38.5F @ 87F ambient

Edit: Compared to what you have gone through, I think I did a lot less work, spent a lot less money and learned a lot more in the process.

__________________
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

And mine was not seized, but was making a squealing noise and not siphoning from the r134a can during the charge. I also later noticed that it seemed to have two types of oil that didn't mix together in it. The not siphoning problem was probably actually caused by some clogs in my lines. The squealing was probably grease or excessive wear on the clutch, or possibly bad bearings.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Refrigerant does not get "siphoned" in from my observations. If you watch your manifold gauges while charging, the suction side pressure in the system is 30 to 50 psi positive pressure, not a vacuum. The static pressure in the R134a can is around 70 to 80 psi depending on outside temperature. The refrigerant is slowly pushed into the system because it is at a higher pressure, not siphoned in, that could take a long time... like 20 minutes or more. If you invert the can and let the refrigerant trickle in as a liquid a little at a time, you can speed up the charging process.

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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 was having a mechanic help me do the charge at the time. He said it was not behaving normally, and that it would not take the charge. He couldnt get much if any of the second can in. Siphoning is a bad term for it, but its what came to mind.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Did he increase the engine rpm to speed up the process? When the engine is revved, suction side pressure drops, refrigerant intake speeds up.

__________________
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