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300SD R4 Compressor Clutch Issues
Hey everyone,
My dad's 300SD seems to be having some clutch issues on the R4. The R4 is--I think 3-4 years old now. The clutch seems to kick on sometimes and other times not. If I give it a tap with a screw driver or pipe it will kick on.. Is there anything I can do for it?
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#2
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Have you checked the pressures with gauges? It could be around the low pressure cut out and cycling on and off due to that. Then make sure the connection on the compressor is solid and it is getting voltage. Once those two are confirmed I would then delve into the compressor. (Perhaps you already have checked that and just didn't mention it )
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2009 ML320 Bluetec 1985 300CD 1981 300TD Past Mercedes 1979 300TD 1982 300TD 2000 E320 4Matic Wagon 1998 E430 1984 300SD 1980 300SD |
#3
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Check the wires. The R4 electrical connection can be tricky to properly hook back up. The spade connectors have a spring-action, but it's easy to miss this and get a pressure fit between the plastic housing and the connector.
I think, but can't guarantee, the coil on the clutch should ohm out at around 4. If the clutch is getting good voltage, but won't close, they can be replaced. I have a spare pull-off on my garage, yours for the cost of shipping (>$10, I'd guess). It was working when I pulled it. |
#4
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I connected up my manifold and the pressures I got were good. The high side was near 150 Psi.
The clutch is definitely getting power, I figured I'd see if the connections were loose and jiggled them with my long screwdriver. Accidentally tapped the positive to the frame--SPARKS. But yes its connected fully. I would surmise that if it was not getting electricity me tapping the front of it would not engage the clutch fully. How difficult is changing the clutch on these R4's? Can it be done on the car? I've never done any work with the compressors.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#5
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Yes, it is getting voltage, but if you put a multimeter on it you will be able to tell if the voltage is constant. There is a chance there is some electrical fault giving an intermittent signal but it does seem like something with the clutch is acting funny. I've never changed one so I'm no help there.
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2009 ML320 Bluetec 1985 300CD 1981 300TD Past Mercedes 1979 300TD 1982 300TD 2000 E320 4Matic Wagon 1998 E430 1984 300SD 1980 300SD |
#6
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The gap between the pulley and the clutch plate is probably too great. I don't remember the specs but between .010 and .005 should be fine. There should be a 1/2 in or 13 mm nut in the center of the clutch disk. See if it will tighten any. You will need to hold the clutch disk with a BIG pair of channel lock pliers or something. If the nut is tight, then replacement of the clutch is do-able on the car with the correct tools. You will need a clutch disk puller, snap ring plies and a pulley puller. Then you will need a clutch disk installer. The snap ring is on the outside of the collar the pulley slides onto. DO NOT remove the snap ring inside the collar, the one close to the input shaft. It holds the front seal in and if you remove that snap ring with pressure on the system, the seal WILL come flying out along with all the freon.
Paul
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84 500 SEL (307,xxx miles) |
#7
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It can be done on the car. I replaced the idler pully bearing on the R$ still mounted in my w123. You will need to get two different tool kits rent one from Auto Zone and the other from O'Reilly. I do not remember the numbers though. I'll look for my old post and then link it.
Here it is: 82 300D How difficult to change a/c clutch?
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K 90 Dodge D250 5.9 Cummins/5 speed. 400K |
#8
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Quote:
Also be aware that this nut is used to set the air gap, it _won't_ " tighten up " like a regular bolt until the plate is pulled fully against the pulley face resulting in the compressor runing full time. Turn the nut only enough to set the gap. Other brands of compressors use shims on the shaft to set air gap. Check the voltage across the plug with it plugged in to be sure you are getting full power. You can cycle the clutch with the engine off as it is safer. |
#9
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If you're getting power, but it's intermittent and closes with a physical rap, then it's possible the coil is cracked or the connections are corroded.
You can remove the wires and connect an ohmmeter to the coil, it should be around 4 ohms, IIRC. The clutch may also just need a really good cleaning and adjustment. I think the gap is less than 1 mm. |
#10
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Ill have to climb under it and check it out. The odo/trip just quit today on it too. So I've gotta take the cluster out and see whats up... Its probably a gear, but I hope it something simpler.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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