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Author Topic: Windshield Wipers on 4104 need help diagnosing  (Read 947 times)
Bill in KS
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« on: March 28, 2011, 12:11:24 PM »

Hey
I have pantograph (sp?) wipers on my 4104.  My drivers side control knob and driver side wiper work well

My passenger side will park fine.  BUT when you turn the knob to run them it will go towards the middle of the windshield and just move back and forth a few inches with a quickly.  I can find a sweet spot in the control knob and fiddle with the shot off valve leading to the inlet side of the valve assembly bolt to the motor and make the wiper sweep from side to side really slow. 

I pulled the control knob and tore it apart and it is clean inside and the Oring on the small spool valve looks to be OK. 

I pulled the wiper motor apart and cleaned the internals , I pulled the caps off of the motor's valve asembly and pulled the small plastic spool valve and those Orings looked OK.  The one spool in the valve assembly that you can't pull moves but it is stiff. 

I started with the same problem I have now except the control and motor are clean inside. 

The control valve will put all of the air out the park side when in the off position and when you turn it " On " it starts to put air out both ports ( prk & mtr ). 

I can't find much info in my service manual concerning how the system flows/operates.

need some help
Bill in KS
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PD4104-4797 in SE Kansas
lostagain
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« Reply #1 on: March 28, 2011, 04:31:54 PM »

I have had good results by replacing the big Orings, 1 on each end of the shuttle piston inside the motor housing, (I don't have the manual in front of me for the proper words to describe the parts). About 2 or 3 inch diameter. They wear on the outside where they rub on the inside of the housing, and don't hold air anymore. Also the lube dries up. I have never been able to find the right size Oring at any parts store. You have to order them from a bus parts supplier. They are not expensive: $2 or $3 each. Lube them and everything else good with grease.

Hope this helps, and good luck.

JC
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JC
Invermere, BC
1977 MC5C, 6V92/HT740
Bill in KS
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« Reply #2 on: March 28, 2011, 07:08:22 PM »

Hey
Thanks for the reply.  I bench tested the motor and shot air into each inlet port and it quickly moved to the correct side and held pressure. 

Bill in KS
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PD4104-4797 in SE Kansas
Lin
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« Reply #3 on: March 28, 2011, 07:24:12 PM »

Also make sure that the wiper motor is exhausting properly.  If the exhaust port is plumbed, a kink the the tube will stop the motor from functioning right.
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You don't have to believe everything you think.
Bill in KS
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« Reply #4 on: March 28, 2011, 10:27:51 PM »

Thanks, I've pulled the exhaust off of the motor while doing my different test

Bill in KS
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PD4104-4797 in SE Kansas
gus
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« Reply #5 on: March 30, 2011, 08:29:17 PM »

Bill,

I had some of those switch problems. As I remember (Been a while ago) I got the exhaust and intake ports reversed after I cleaned/repaired the valves and caused some really weird operations!

It is also easy to get that little black thingy in the valve in wrong. Again, I'm trying to drag all this from my aged memory!!
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PD4107-152
PD4104-1274
Ash Flat, AR
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