Bleeding trailer brake actuator

S

ssobol

Active member
I found that the surge brake actuator on my MagicTilt trailer was not working. The mechanism is all rusted up.

I got new one (UFP-75a with backup solenoid). I installed it and bled the master cylinder according to the instructions (move the actuator rod with a screw driver until no more bubbles in the reservoir). Then I tried bleeding the brakes.

I opened the bleed valve on the caliper (self bleeders) and moved the actuator rod with the screwdriver. I noticed that the reservoir did not deplete much at all. I opened the bleeder more, and still no fluid went out of the reservoir. I opened the brake line at the first tee and tried again (to see if the line was blocked). Same thing, no depletion from the reservoir and no fluid out the line.

I removed the actuator, disconnected the outlet line, and moved the rod again. A little fluid comes out every once in a while when the rod is moved, but most strokes result in nothing happening. Sometimes I can hear a sucking noise when the rod is moved coming from the outlet. I can see the rod moving in the port at the bottom of the reservoir.

I expect that there should be a decent squirt of fluid whenever I move the rod, but this is not happening.

Is there some thing I overlooked or some trick to getting the actuator to work so I can bleed the system? Perhaps I have a defective actuator?
 
I think you are on the right track. When you bleed the system you must attach a small hose to the bleed valve and the hose must go into a container containing some brake fluid. This because when you open the brake bleed valve it can and will suck air back the other way and you don't want that. They make a kit for this for less than 10 bucks. See NAPA or whatever parts store is close.

Also, to get the most travel when bleeding the brakes on the actuator, put the stinger in it (the one you use for towing) and use it for leverage as it is hard using the screwdriver method to really move any fluid. The screwdriver is inefficient for sure. I use my power brake bleeder.....I cheat.....LOL.....The stinger will work well to get leverage on it.

If the system was rusted as you say, you may also find you need new calipers....or to rebuild them....Do they move when you put a c-clamp on the pistons? If they are stuck, you will need to free them or replace them.
 
I did have a Magic Tilt trailer. I did change the coupler and the cylinder as a unit. Are the brake lines clear? Can you blow air in the lines and the calipers move? If the lines are clear ,you should see brake fluid at bleeder screws. Magic Tilt Trailers does have a web site. On the site, they have instructions on how to bleed brakes. Neal
 
When I first looked at the brakes I took off each bleed nipple. Only one had evidence of fluid on it. It appears that the system is pretty much dry.

I put on speed bleeder valve so there should be no reverse suction when I try to bleed the lines.

When I tried to bleed the first brake caliper, I pumped the rod in the actuator for awhile but the fluid level did not deplete in a regular fashion (i.e. a little each pump).

What I have noticed is that after disconnecting the actuator from the trailer and actuating the rod with a screw driver, fluid only comes out of the port of the solenoid value once every several strokes. I would expect that moving the actuator rod should produce a squirt of fluid on each stroke.

I am trying to determine if the actuator is bad (although I bought it new) or if I am doing something wrong.

I expect that one or more of the calipers are locked up, but until I get fluid in the system it will be hard to tell. Even if the piston can be moved with a c-clamp, it may not move under the fluid pressure.

Stefan
 
It would not surprise me in the least bit that if the master was rusted, everything else is too. The brake lines should be clear or it won't work. If you are getting a good squirt out of the actuator, eventually it will make its way to the pistons - that is if the lines are clear......Due to the fact you had rust and gunk, I'd probably change everything if it was my trailer.
 
The problem is that I am NOT getting a good squirt out of the actuator. I get a half-*ss** squirt once in awhile (about every 6th stroke).
 
Are you moving the piston with a screwdriver thru the top access port or are you pushing the entire unit back and forth on the trailer tongue? If the unit is good; after you have bled the resivoir, cylinder and the outlet line, if you seal off the outlet, when you pump it with a screw driver or pry bar, it should hold pressure. That will tell you if the piston and cylinder are good.
 
Ok, bled the system. Most of the calipers are in poor condition. Looking at the MagicTilt parts catalog there are two types of caliper listed. My trailer has the UFP calipers. Apparently UFP makes two models of caliper, DB-35 and DB-42.

Does anyone know which caliper is used by MagicTilt? Looking around online, I can find the UFP calipers for about 1/2 what the MagicTilt part number goes for, but I'm not sure which to get.

I cannot not find an identifying part number on my calipers, although I have not taken one off yet. That's going to be a pain because the bolts are rusted and I don't want to do it until I have the replacement parts.

Thanks,

Stefan
 
I can't help you specifically, but I do have a Magic Tilt trailer, so I can maybe give a helpful tip. (Mine came with unfit drum brakes on one axle only, so I immediately went to Kodiak discs on both axles.)

Sadly, unless they have changed their tune, you cannot talk to Magic Tilt directly. Their policy is not to speak with customers. This would be fine, except in my experience their dealers cannot always get the necessary information from Magic Tilt either (though they try).

That said, there is a big Magic Tilt dealer in Sarasota, Florida, who did their best to help me over the phone. You might try them (I think it's called Magic Tilt of Sarasota or something obvious like that).

Sunbeam

PS: I do like my trailer and it tows beautifully; I just wish it were easier to get info/help from Magic Tilt. Especially when one has already taken the time to look at their website and contact a dealer, and still needs information/help.
 
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