Broken wiper fluid pump mechanism - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Reese Allen · 02-26-2015, 02:24 AM

When I turn on the windshield wipers in my 1980 C20, the wiper fluid pump always runs. At first I figured this was an electrical issue, but after digging deeper, it turns out there is a finicky mechanism which connects the wiper motor to the wiper fluid pump, and the problem seems to be in there somehow. I just can't figure out exactly how it's not working.

I made a video:

https://www.youtube.com/watch?v=9m0Yo09Cl9Q

Any ideas?

chengny · 02-26-2015, 06:42 AM

Description of operation:

KrazyRay · 02-26-2015, 09:12 AM

Its very simple to swap out your washer reservoir bottle with an 85 and newer and reroute the wires to the pump inside the bottle. Every 84 and older washer I have come across did not work.

Reese Allen · 02-26-2015, 11:37 PM

Thanks chengny, useful documentation. I think I understand better now what's going on. Having said that, I still can't figure out how to fix it. It seems like at least one of these parts needs to be replaced, and finding tiny little replacement parts like this will be impossible.

I think I'll follow KrazyRay's advice. I definitely can't fix this pump, but I can certainly disable it and install a pump and reservoir from a newer model.

**hatzie** · 02-27-2015, 12:12 PM

You can fix it. Easier than re-wiring for a new pump and reserviour.
The teeth on the plastic ratchet gear #7 are worn out so it's not camming all the way back around to the STOP position. The GM repair kit is GM Part # 4939314

BTW When it stops pumping fluid the pump soft parts are real easy to change out. You can get a kit with Parts 2, 3, & 4 on the HELP rack at NAPA etc.

http://www.ebay.com/itm/New-Genuine-AC-Delco-GM-4939314-Ratchet-Package/181401685956

Reese Allen · 03-01-2015, 09:42 PM

Well, I went to the junkyard and got a tank with a tank-mounted pump out of an '85 Suburban for $14. Installation took 10 minutes, including splicing the wires for the new pump. Works great although the wipers will continue to crank for ~10 seconds after the fluid stops spraying. The root problem (fluid always sprays when the wipers are on) has been solved so I'm happy.

Hatzie, thanks so much for your post. I wish I had seen it before I went to the junkyard. I'm skeptical that replacing the ratchet gear would fix this, though. It didn't seem like having bigger/sharper teeth on the ratchet gear would help. The pawl/arm thing would reach for the next tooth but come up short by at least 1/8". Forcing the gear to turn using my fingers until the pawl could get the next tooth took a lot of force.

http://imgur.com/a/RsXPa

badchevy · 03-02-2015, 03:19 PM

The washers on my '82 are doing the same thing. Only thing is the motor and pump are new. I took the cover off and everything is working fine. The gears are good and the washers turn off but there is still fluid coming out when the wipers are on.

02-26-2015, 02:24 AM	#1
Reese Allen Registered User Join Date: Feb 2015 Location: Seattle Posts: 14	Broken wiper fluid pump mechanism When I turn on the windshield wipers in my 1980 C20, the wiper fluid pump always runs. At first I figured this was an electrical issue, but after digging deeper, it turns out there is a finicky mechanism which connects the wiper motor to the wiper fluid pump, and the problem seems to be in there somehow. I just can't figure out exactly how it's not working. I made a video: https://www.youtube.com/watch?v=9m0Yo09Cl9Q Any ideas?

02-26-2015, 06:42 AM	#2
chengny Registered User Join Date: May 2007 Location: New Hampshire Posts: 349	Re: Broken wiper fluid pump mechanism Description of operation: Last edited by chengny; 02-26-2015 at 06:48 AM.

02-26-2015, 09:12 AM	#3
KrazyRay Registered User Join Date: Jun 2009 Location: Oroville, CA Posts: 4,827	Re: Broken wiper fluid pump mechanism Its very simple to swap out your washer reservoir bottle with an 85 and newer and reroute the wires to the pump inside the bottle. Every 84 and older washer I have come across did not work.

02-26-2015, 11:37 PM	#4
Reese Allen Registered User Join Date: Feb 2015 Location: Seattle Posts: 14	Re: Broken wiper fluid pump mechanism Thanks chengny, useful documentation. I think I understand better now what's going on. Having said that, I still can't figure out how to fix it. It seems like at least one of these parts needs to be replaced, and finding tiny little replacement parts like this will be impossible. I think I'll follow KrazyRay's advice. I definitely can't fix this pump, but I can certainly disable it and install a pump and reservoir from a newer model.

02-27-2015, 12:12 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Broken wiper fluid pump mechanism You can fix it. Easier than re-wiring for a new pump and reserviour. The teeth on the plastic ratchet gear #7 are worn out so it's not camming all the way back around to the STOP position. The GM repair kit is GM Part # 4939314 BTW When it stops pumping fluid the pump soft parts are real easy to change out. You can get a kit with Parts 2, 3, & 4 on the HELP rack at NAPA etc. http://www.ebay.com/itm/New-Genuine-AC-Delco-GM-4939314-Ratchet-Package/181401685956 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 03-05-2015 at 03:53 PM.

03-01-2015, 09:42 PM	#6
Reese Allen Registered User Join Date: Feb 2015 Location: Seattle Posts: 14	Re: Broken wiper fluid pump mechanism Well, I went to the junkyard and got a tank with a tank-mounted pump out of an '85 Suburban for $14. Installation took 10 minutes, including splicing the wires for the new pump. Works great although the wipers will continue to crank for ~10 seconds after the fluid stops spraying. The root problem (fluid always sprays when the wipers are on) has been solved so I'm happy. Hatzie, thanks so much for your post. I wish I had seen it before I went to the junkyard. I'm skeptical that replacing the ratchet gear would fix this, though. It didn't seem like having bigger/sharper teeth on the ratchet gear would help. The pawl/arm thing would reach for the next tooth but come up short by at least 1/8". Forcing the gear to turn using my fingers until the pawl could get the next tooth took a lot of force. http://imgur.com/a/RsXPa Last edited by Reese Allen; 03-01-2015 at 09:58 PM.

03-02-2015, 03:19 PM	#7
badchevy Registered User Join Date: May 2010 Location: San Antonio, TX Posts: 102	Re: Broken wiper fluid pump mechanism The washers on my '82 are doing the same thing. Only thing is the motor and pump are new. I took the cover off and everything is working fine. The gears are good and the washers turn off but there is still fluid coming out when the wipers are on.



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