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  #46  
Old 08-15-2007, 03:37 PM
vstech's Avatar
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what year is your SD?
if it's post 86, you HAVE to get it fixed and soon!
if it's Pre 86, it is a concern, but no major problem. that said, a new clutch, or a pulled fan from a post 83 donor car would be ok.

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  #47  
Old 08-15-2007, 03:38 PM
Craig
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That sounds like the fan clutch. It's pretty easy to test, it should be fully engaged when the engine is hot. Try stopping it with a rolled up newspaper and see what happens. You should be able to stop it with a cool engine, but with a hot engine you should not. Also, when the engine is shut off hot, it should stop quickly, not continue to spin around a couple of times. BTW, is the electric fan working?
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  #48  
Old 08-15-2007, 03:40 PM
Craig
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Per his first post, its a 83 617.
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  #49  
Old 08-15-2007, 03:52 PM
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Quote:
Originally Posted by Craig View Post
That sounds like the fan clutch. It's pretty easy to test, it should be fully engaged when the engine is hot. Try stopping it with a rolled up newspaper and see what happens. You should be able to stop it with a cool engine, but with a hot engine you should not. Also, when the engine is shut off hot, it should stop quickly, not continue to spin around a couple of times. BTW, is the electric fan working?
The auxiliary fan? Yes. That was one of the first things I checked.
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  #50  
Old 08-15-2007, 03:54 PM
Craig
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Quote:
Originally Posted by TJR300SD View Post
The auxiliary fan? Yes. That was one of the first things I checked.
I figured that was too easy. Check the fan clutch when you have a chance and let us know, I suspect that's the problem.
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  #51  
Old 08-15-2007, 04:39 PM
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Quote:
Originally Posted by Craig View Post
I figured that was too easy. Check the fan clutch when you have a chance and let us know, I suspect that's the problem.
I tested it like you said, and well, the cause is now more elusive. The fan did NOT stop when I put a rolled up newspaper against the blades. It just kept spinning hard and pushed the newspaper away with every strike. It also stopped INSTANTLY when I shut off the engine. So it appears to be fully engaged. (This is with the engine at 90C).

BTW, does the fan vary its rpm depending on the temp? Does it spin faster when the coolant is hotter? When I was in Washington, I thought I used to hear it get louder when it gets hot. Or maybe that was just the aux fan kicking in.
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  #52  
Old 08-15-2007, 07:43 PM
Craig
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Well, it sounds like the clutch is OK. It just runs at the engine speed when it's engaged and "slips" when it's not. I can hear the electric fan start on my car.

I would start looking at the cooling system. What sort of flush was done, was the engine run with an acid flush, or was it just rinsed out? If you search you will find some info on performing a citric acid flush, that might be the next step if you are confident the thermostat is good.
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  #53  
Old 08-15-2007, 09:39 PM
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On my 1985 300D, i retrofitted with a system flush then a number of new parts and used R134a. Car cools OK .
When i do my 1982 300CD i am going with freeze12 for lower head pressure and cooler temps in the car.
I am a fan of Dieselgiant.com
I have purchased the freeze12 already from NAPA for $7.50 per can , though it will be some time till the ac is repaired.
Seriously considering having R134a removed from the 300D and replacing it with freeze12 which is more compatable with the condenser.
I am in South Carolina.
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  #54  
Old 08-15-2007, 10:21 PM
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How about a little more info on this 100% recic. 30min. fix?? Thanks

Quote:
Originally Posted by ichbineinekrous View Post
forcing the system to do 100 re-circulated air while in any of the a/c settings is a 30 min. fix, and one I would recommend to anyone wanting to maximize cooling. I agree that upgrading your condensor to a larger one is probably the most cost effective way to boost your car's ability to overcome hot ambient temps. If you can't expiate the heat energy from the refrigerant it cannot be compressed as much and that's the whole shootin' match, regardless of which flavor of refrig. But r-12 is better, if you don't mind paying a couple hundred bucks every couple years (if youre lucky) when u replace the compressor.
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  #55  
Old 08-15-2007, 10:30 PM
Craig
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Originally Posted by tjseitz2001 View Post
How about a little more info on this 100% recic. 30min. fix?? Thanks
I'm sure someone knows the details of the "fix" but be aware that the system should be on approximately 80% recirculation anyway. My (R-12) system does just fine in 100F+ ambient conditions without any "improvements."

IMHO, a well maintained system running on R-12 is the way to go.
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  #56  
Old 08-15-2007, 10:57 PM
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Quote:
Originally Posted by Craig View Post
I'm sure someone knows the details of the "fix" but be aware that the system should be on approximately 80% recirculation anyway. My (R-12) system does just fine in 100F+ ambient conditions without any "improvements."

IMHO, a well maintained system running on R-12 is the way to go.

My R-12 has just been rebuilt,new comp,expantion valve,new condenser,dryer and switches,cleaned and flushed. It is doing pretty well in the 100+ temps and high humidity in Atlanta GA.42 to 47 degress As long as you are moving above 40mph. Get in stop and go and the vent temp will get up to 55 and 60 degrees. I would like to do something to do better than that.The day after I rebuilt it, on a cool morning(55 to 60 low humidity IIRC) I got 37 degrees out of it. Could a old or worn aux. fan be causing some of this?? I like the idea of the larger 560SEL elc.fan. Would this help?? Tom 300D
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  #57  
Old 08-15-2007, 11:14 PM
Craig
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It sounds like you've done everything else, a larger fan might make the "stop and go" performance closer to the "highway" performance. The compressor will still be turning more slowly, but the heat transfer should be better. You need everything you can get in that humidity. I don't know if the old fans can slow down, mine appears to be operating at a very healthy speed (I can hear it from inside the car when it starts). It would be interesting to see data if you decide to try a larger fan.

BTW, I'm assuming your evaporator drain isn't clogged.

From looking at my W123, I don't know how easy it would be to install a larger fan with the braces in front of the condenser. It appears that the braces would have to be "redesigned" to make some extra room.

Fortunately, I spend very little time in traffic. My comments were based on mostly highway driving.
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  #58  
Old 08-15-2007, 11:29 PM
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Quote:
Originally Posted by Craig View Post
It sounds like you've done everything else, a larger fan might make the "stop and go" performance closer to the "highway" performance. The compressor will still be turning more slowly, but the heat transfer should be better. You need everything you can get in that humidity. I don't know if the old fans can slow down, mine appears to be operating at a very healthy speed (I can hear it from inside the car when it starts). It would be interesting to see data if you decide to try a larger fan.

BTW, I'm assuming your evaporator drain isn't clogged.

From looking at my W123, I don't know how easy it would be to install a larger fan with the braces in front of the condenser. It appears that the braces would have to be "redesigned" to make some extra room.

Fortunately, I spend very little time in traffic. My comments were based on mostly highway driving.
E-vap.drain pluged?? I dont think so. everytime I stop there is a LAKE under the car.
As far as room for a larger fan. That was my thinking too. I'll take a closer look at it tomorrow. If I decide to try it I'll be sure to report back. Tom 82 300D
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  #59  
Old 08-15-2007, 11:36 PM
Craig
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Quote:
Originally Posted by tjseitz2001 View Post
E-vap.drain pluged?? I dont think so. everytime I stop there is a LAKE under the car.
That's a good thing, all that humidity could be inside the car. Mine was partially clogged (I didn't notice until I drove to MN in the summer) and it did seem to reduce the AC performance. It eventually overflowed when I made a left turn, I ended up replacing the drain (common problem).
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  #60  
Old 08-16-2007, 02:22 AM
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yeah its worth it. just get yourself a york pistion air compressor put on there, and you will never have trouble with ac again.

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