Surge Brake Help

[MN Ryan]

bturner Hoping you can lend some advice:
Something let loose in my actuator/master cylinder this spring which poured brake fluid out and has left me without brakes. I have very limited experience with brakes, but I've found some videos and think I can tackle this. Plus, I don't want to wait 6 weeks for service and pay exorbitant fees for something I can do. This is a Tiedown LP70 with disc brakes.

Questions (see photo):
1) Do I want to disconnect the actuator on the master cylinder side or the brake line side?
2) Any advice to avoiding leaks when I install the new one? Knowing myself, it'll leak and I'll get super annoyed and swear a ton.
3) Kind of hard to see, but there is a short, rubber tube (above the solenoid) coming out of the actuator. It isn't attached to anything--I'm thinking it isn't intended to be attached to anything. WTF is it?

Thanks!

[bturner]

Disclaimer..... I've worked almost entirely with Dexter A60s so anything I reference here is going to be based on that.

Depending on the model you have, you may have found your problem. Been a while since I had one apart and there are some differences in how they're plumbed but the cylinder at the end that the brake line is attached to is the reverse lock out solenoid. The solenoid is energized by the backup light circuit and (in this case) redirects the brake fluid that would typically activate the calipers back to the master cylinder reservoir via that rubber tube. If that rubber tube is perished, damaged or disconnected, brake fluid is going to gush out when backing up. The newer ones I've worked with just block the fluid from entering the brake system which achieves the same result without the plumbing. At least that's how I remember it. A lot of people will tell you the redirected fluid option is better as you don't pressurize the MC when backing up. Is that true? IDK, it makes sense but I think you mostly see the blocking versions these days or some that do the redirection internally without needing that hose.

Since you have a black hose heading towards the master cylinder reservoir, I would assume you have the return line version. If so you can see in the diagram below the routing.







As to how I would go about this without a big mess. Sorry, one thing that I just deal when doing brakes is spilled/leaking brake fluid. You can certainly try to limit it by emptying the reservoir with something like a turkey baster but past that I pretty much try to use strategically placed drip trays and have something like glass cleaner and rags ready to clean up any brake fluid that gets on any painted surfaces. The last 2 I did had folding tongues so disconnecting was pretty straight forward at the rubber flex line when you fold the tongue. In this case it looks like you don't have a folding tongue as you have a steel line going directly into the reverse solenoid.

I've done these both ways depending on access the flair nut. You have to consider both assembly and disassembly. Getting that nut off at the solenoid may be easy but getting it to thread back on may be challenging. Since you're going to have to bleed the entire system anyway, if you have clear access to where that line Y's or a union by the winch post, I would be tempted to disconnect it there, pull the actuator forward with the line attached so you have unrestricted access to the solenoid as you'll probably be replacing at least the rubber line. All of this would of course be predicated on having clear access to that rear flair nut and being able to easily route the brake line forward and back. Another thing to have ready is something at about the same height as the actuator so you can set it on something once you've moved it out of the shell. Ask me how I know about that.....

There's really not much else there to leak like you describe unless the seals in the master cylinder have completely gone in which case I would be looking to swap the whole unit out. In theory these should be easy to rebuild and I've heard of people doing them or changing the shock and/or rollers. My dad used to do all that stuff and I grew up watching him do it. He was an old army mechanic and would reuse gaskets, hoses or whatever. He had a collection of hones, gaskets sets and buckets of bolts that he would constantly reuse. It got to the point where I would cut up all the gaskets as he took things apart so he'd have to use the news ones I purchased. I was so traumatized by this that I now typically fix things like this in chunks. In this case if it's that line fine, but if you have to go in and start replacing seals in the MC, do yourself a favor and replace the chunk (inner actuator). That or be prepared to have a trailer brake hobby this summer.....

Or bring it over to my house in Brighton and we'll knock it out over some beers. I even have a Motive Action power bleeder to bleed the brakes with.

[MN Ryan]

Ah, you may have saved me a chunk of change. Your explanation makes sense. I'll dig into it!

If you were closer, I'd haul it over with a cooler of beer. Weed certainly have a fun time.

I truly appreciate your experience and willingness to help!

[SilentSeven]

Wait...what? A reverse lockout with a return line? That's a first for me. I've always seen them inline to the master cylinder output with no return line. Had to look that up. You must have one of these. https://www.easternmarine.com/tie-do...olenoid-11253a

I'm like bturner and am familiar with the Dexter line; here's the 70LP parts diagram and I can see the solenoid with the return line.



If this was my trailer, I'd either replace both the master cylinder and reverse lockout solenoid or even consider putting an entire new coupler on. You can always try to debug the leak but if one part has failed they are all likely suspect. Better just to refurbish all the coupler fluid parts in a single pass IMO.

Bleeding a trailer is always a PITA and I'll also give a thumbs up for the Motiv bleeder with the trailer adapter bturner mentions. I've got one as well...don't use the trailer adapter much but it's glorious vs a manual bleed.

https://www.motiveproducts.com/produ...nd-marine-kits

Never love brake work but love it when my brakes work.

[MN Ryan]

Thanks, guys. They have been working fine till now. I'm now confident that that return line popped off. I just can't see the fitting from below.

[MN Ryan]

Ok, I can definitely feel that fitting. Unfortunately, getting it back on and secured without disassembly will be impossible. Grr.

[bturner]

Wow, that's great, I think. Looking at the picture it would look like someone has been in there before. It could just be the picture but the nuts look like someone may have been at them in the past. If you pull it apart I would suggest replacing the rubber return tubing and getting spring clamps for the line ends. There shouldn't be much in the way of pressure on that line as it should just be routing fluid back to the reservoir but brake fluid is nasty stuff and if it's been on these for years I doubt it will be in very good shape.

Remember the 5 P's.... Proper Planning Prevents Poor Performance....

[MN Ryan]

Yeah, I did have this master cylinder replaced a few years ago, so it has been pulled apart (by a trailer shop).

[XBIGPUN66]

I leaned in the nuclear navy that there are 7 p's. Poor prior planning promotes piss poor performance.

[MN Ryan]

Just wanted to circle back here and say thanks to bturner and SilentSeven for the outstanding advice and confidence to tackle this. I got around to it last Friday and finally took her for a test drive this afternoon (family wedding, travel baseball, and travel softball schedules ). No drips and everything is working well. You saved me a bunch of money, too. All it took was a new section of hose, a couple hose clamps, and a bottle of brake fluid. I got an assist with bleeding from our 13YO.

[bturner]

Glad to hear that worked out for you. Even better that your 13YO was a part of the solution. Believe it or not small interactions like that can be life changing and really help build a bond. I still remember being given the job of tool gofer for my father. Learned a lot about tools and fractions as I figured out the requests for various tools and wrenches.