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Old 08-18-2017, 06:54 PM
Jab Jab is offline
Join Date: Apr 2017
Location: Tampa, FL
Posts: 38
Default RV4 brake bleeding

Hi all

Just posting this to help anyone else who suffers the miserable fate of needing to bleed their brakes without much prior experience on RV's. There is already a wealth of information on this forum on how to connect pumps etc so I won't repeat that. However, I understand the RV4 layout is different to other RV's and those tried and tested methods still left me with no brake pressure. There is a loop in the brake line just above the pucks, and the line from the master cylinder to the firewall also makes an arc above the unions, both places seem to be prime collection points for air bubbles.

After pumping fluid up from the bleed nipple to the reservoir, I disconnected the line going into the top of the master cylinder. I kept pumping to make sure fluid was getting to that union then closed the bleed nipple. I then attached the tubing to the top union of the master cylinder and pumped fluid through the master cylinder to the reservoir. After reattaching all the lines I had great brake pressure. Hope this helps someone else.

Bought RV-4
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Old 08-18-2017, 07:16 PM
William William is offline
Join Date: Nov 2006
Location: Sarasota,Florida
Posts: 390

Great write up Gary. Glad you got those brakes working well. This is Bill based at kvdf with the RV6A

Take care
RV6A flying as of November 8, 2016. N717WK
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Old 08-20-2017, 03:16 PM
Xkuzme1's Avatar
Xkuzme1 Xkuzme1 is offline
Join Date: Jan 2015
Location: KC, MO
Posts: 292

I have found that using an airpump nipple at the top of the reservoir for 5-7 seconds at a time is a good technic.

Takes two people. Have one person crack the bleeder screw at the bottom just a split second before you pressurize the reservoir (that is topped off). Then close the bleeder screw and refill the reservoir. Keep doing that until there are no air bubbles coming out of the bottom bleeder screw.
RV-4 - 0-320 (160HP)
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Old 09-05-2017, 09:47 AM
Pat Falley Pat Falley is offline
Join Date: Jun 2013
Location: Encinitas, CA
Posts: 19

I spent two weekends figuring it out the first time.

You can bleed the brakes without disconnecting any lines. You have to remove the bolt that connects the master cylinder to the brake pedal at the bottom. Then you can rotate the master cylinder about 95 deg., that gets the lines such that you can pump fluid in from the bottom all the way to the reservoir without any place for bubbles to get trapped. It an easy one man job.

BTW, I use an elastic nut on the cylinder to pedal bolt that has to be removed. It's easy to see, you can check it as you strap in. I was worried my shoe would snag the specified cotter pin arrangement, I know of at least one ground loop caused by that happening.
Pat Falley
RV-4 - flying (bought)
SNJ-5 - ground up restoration, almost done.
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Old 09-05-2017, 03:18 PM
Mark Albery's Avatar
Mark Albery Mark Albery is offline
Join Date: Jul 2007
Location: Fremont CA
Posts: 614

I had this issue and unhooked one end of the cylinder to rotate it such that the reservoir inlet was above the outlet. I then decided to put in Matco cylinders which will fit the other way round.
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