No Fluid in Brake Line and Trailer Brakes Locking up

Question

Question:

Trailer brakes o one side lock up when braking then won’t release. Unhooked brake line and engage brakes on pickup no brake fluid comes out .any ideas? Solenoid, actuator?

asked by: Greg E

0

Expert Reply:

Hi Greg,

Based on what you’re describing, if you cracked the brake line and got no fluid when the brakes were applied, that points more toward that the system isn’t building or sending pressure at all. In a surge setup with a lockout solenoid, fluid should still come out unless something upstream is blocking it or the actuator isn’t doing its job. There could be a blockage in the line or a problem with the master cylinder inside the actuator.

A good next step for you would be to crack the line right at the actuator outlet or just after the solenoid and then compress the coupler. If you still get no fluid there, that pretty much confirms the actuator is not pressurizing. If you do get fluid there but not further down the line, then you’re looking at a blockage or collapsed line downstream.

Let me know what you find out and I am happy to troubleshoot further.

expert reply by: Heather A

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Greg E.

3/18/2026

What if actually trying to say is how can I get t the boat and trailer home so I can work on it. It is sitting 60 miles from my home Please let me know how I can get the brakes r ( at least temporarily) released so I can get it home safely. Thanks Heather God bless

Heather A.

3/19/2026

@GregE Geez, I'm sorry you are dealing with this Greg. There are a few things you can try to help free it up. First, try slowly backing the trailer up a few feet. That can sometimes help knock the brake shoes loose. If that doesn’t work, you can back off the adjustment rod, basically adjusting the brakes in reverse, to relieve some of the pressure on the shoes. You can also try gently tapping around the outside of the drum with a hammer while pulling it off. This can help break it free. Just keep in mind the drum can be pretty heavy. Some folks will even leave the tire and wheel on to give themselves a bit more leverage when pulling. Once you get it free, just drive slowly give yourself plenty of room. Let me know when you make it home!

Larry

3/19/2026

This happened to me when I installed my new brake actuator on a new to me trailer. Went to bleed the brakes and no fluid would come out of one caliper. I took it apart and removed the brake line. Squeezed the piston on the caliper and it was like play dough noodles coming out. I removed the piston and cleaned out years of built up debris, inspected o rings and boot and reassembled. Brakes bled perfectly.

Heather A.

3/19/2026

@Larry Thank you for the advice Larry!

Answer 1

Hey Mark, yes the Demco surge actuator part #DM72VR can be used to replace the Atwood surge actuator you have currently. You most likely won't have to really change anything. There is probably a flexible brake line that attaches to the back of…

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Answer 2

Thanks for the kind words, happy we were able to help, and the photos are also appreciated! As for the actuator, you are correct that the Atwood 85736 master cylinder is no longer available because Atwood was bought out so your best option is going…

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Answer 3

Demco does not offer a manual lockout for the coupler part #DM72VR but they do offer an electric option with the part #DM5836. They also recommend installing free-backing brake assemblies on the axles instead too which I attached a link to a page…

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Answer 4

The replacement I recommend for an Atwood Surge Brake Actuator 85778 is the Demco Hydraulic Brake Actuator part #DM62VR. It has the same ball size, offers a bolt-on install, and has a greater capacity. The only difference is it has an electric…

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Answer 5

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 6

According to Blue Ox, it'll take an experienced installer about 4 to 5 hours to complete the installation of their #BX1128 Base Plate Kit on a 2016 Jeep Grand Cherokee. The install isn't what I'd call super-difficult, but the installation…

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Answer 7

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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Answer 8

The #84 spindle is just a common way to identify the spindle dimensions typically used for 3,500 lb axles. So instead of listing out the parts, people can just say they have #84 spindles and it's easier to know what fits it. The CE Smith Trailer…

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Answer 9

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 10

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 11

The Demco Hydraulic Trailer Brake Actuator part #DM72VR should be a direct replacement for the Atwood 61101 Brake Actuator that you have now. This newest updated it rated at 7K instead of 6K. This is a bolt on option that mounts on 3" centers.…

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Answer 12

Hi Calvin! All of the pre-greased hubs/drums, like the Terran Industries Trailer Hub and Drum Assembly - 3.5K Axles - 10" Diameter - 5 on 4-1/2 #TX68VJ, come with bearings made overseas and are all basically the same quality. At least that I…

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No Fluid in Brake Line and Trailer Brakes Locking up

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