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Old 08-16-2009, 04:35 PM
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Join Date: Mar 2006
Posts: 21
Dumb A/C Move

I was working on my `81 300D a/c today. In a nutshell , I was pulling a vacuum on the system, and decided I had not added enough oil to the system. I disconnected the suction hose at the schrader valve union (top of engine, foam insulated hose) and off course, sucked the o-ring into the line! I removed the suction line from the compressor manifold and blew compressed air through it- no o-ring. I`m hoping 1. That the o-ring didn`t make it down though the compressor manifold to the compressor and, 2. That it didn`t go the other way towards the evaporator (would rather not pull the expansion valve to gain access to the line). I will flush the hose I removed with Dura II tomorrow in hopes that a liquid flush may dislodge the o-ring. I think the sealing washer at the compressor would probably stop the o-ring prior to it actually entering the compressor (but obviously I`d rather not have to pull the manifold- it`s a pain with a stepped port compressor!) . Any ideas, tips, etc would be appreciated (or just have a good laugh on me!! I knew better.).

1980 300D, 1984 300d Euro,
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Old 08-16-2009, 04:40 PM
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Join Date: Sep 2001
Location: central Texas
Posts: 17,281
OUCH... that really hurts...

"That the o-ring didn`t make it down though the compressor manifold to the compressor and,"--diesel pilot

now THERE is a time where having an inline filter before and after the compressor would have really come in handy.... but anytime I mention it several people have hissy fits about the ' cost'... LOL
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Old 08-16-2009, 05:19 PM
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Join Date: Mar 2006
Posts: 21
Compressor Screen

I think a screen is a great idea. There is a company , Airsept ( that makes screens for R-4 compressors that fits into the manifold. I`m trying to get them to sell to me (they are set up to wholesale). It looks like a neat system, judging from the website.
1980 300D, 1984 300d Euro,
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Old 08-16-2009, 07:09 PM
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Join Date: Dec 2004
Location: Nashua, NH
Posts: 3,956
At first I thought you meant you somehow sucked an o-ring into the charging port but now I understand you opened the large union while the system was still under vacuum and sucked in the o-ring at the union, right?

You can access the other end of the hose from the bottom of the evaporator above the passenger footwell and blow back through it from there, it is not that hard to do. I just replaced that hose on my wagon and it is not hard to remove it if you have to...takes all of about an hour to pull out the battery tray and air cleaner to get it out but to blow back through it you don't even have to do that. The hose gets smaller in diameter and I would bet the o-ring is stuck in the rubber hose somewhere between the union and the end with the metal fitting.

This is why I like those little 2 oz oil muss no fuss with opening the system to add it.
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz
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Old 08-16-2009, 08:46 PM
rrgrassi's Avatar
mmmmmm Diesel...
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,121
How can an o ring get sucked in? It has to get over the line that is inside the o ring.

Either way, you need to get it out.


70's Southern Pacific #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 133K miles-replaced the other '06 that quit after 300k miles. (did not catch the bad cam in time)

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 195K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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