Pressure Bleeding Surge Brakes

[Frank C]

Jim Powell, a BMW guy, created this Pressure Bleeder webpage to share his backyard version of a pressure bleeder. I stumbled across it while surfing aimlessly tonight, and thought it was terrific, especially to speed up the process of bleeding surge brakes.

Backyard Pressure Bleeder (or just an Ace garden sprayer?)



P.S. Edit: Not only will this widget make bleeding the brakes a snap, but another big advantage is making it really easy to completely replace the brake fluid each year. Brake fluid attracts moisture ... trailers get dunked regularly ... can't hurt! (I went so far as to capture an MHT filecopy - just in case it drops off the web before I getuit.)


( It might even be doubly pleasing for anyone with FOUR bleeder screws! )

[Frank C]

Also found a "commercial" Pressure Bleeder that looks eerily similar ... excepting that price!

EGR Severe Service Brakes is now offering a pressure bleeder for automitve hydraulic systems (brakes and clutch). The kit includes a pressure vessel and two universal fit master cylinder covers,

The system worked quite well. It safely forced the old fluid out and the new fluid in. It bleeds the master cylinder as well, so no need to bench bleed it if you ever need to replace it. No need to have your buddy or significant other come out to help you as you yell "PUMP" and "STOP" from underneath your truck as you open and close bleeder screws all day. ....
For a limited time, EGR is offering this kit for $149, a savings of $40!

( P.S. I'd have sworn that I saw here in recent past that someone posted a reference or link to a pressure bleed system. Try as I might, I couldn't ferret it out tonight - hence my idle surfing. If anyone remembers related links, please be sure to add them. )

[kmclemore]

For many years I've used Gunson's "Ezibleed" pressure system on my English cars - it works a treat. One nice feature is that it comes with a push-on clamp fitting to use a tire's pressure to feed the bleeder. I haven't tried to see if their selection of caps fits the trailer's brake master, but if not I would imagine it would be easy to find a cap and modify it to suit... haven't had a need to bleed my trailer's brakes yet!


BTW, not to digress, but Gunson also makes a *wonderful* tuning tool, their "Colortune"... it's a clear sparkplug that you install temporarily and you can actually see the color of the burn whilst adjusting the mixture - white flame is too lean, yellow is to rich, and blue is just right! I use two of them when adjusting multiple carburettors - one in each end of the motor (cylinder #1 and #4) and that gives me a good idea of the mixture across the motor. Not sure how well it works for 2-strokes - I'd imagine it works similarly - but for 4-strokes it's EXCELLENT.



I use a UniSyn manometer to balance the air-flow across the carbs, and between the two adjustments (fuel & air) the carbs end up nicely balanced. I haven't tuned my boat's carbs yet - they are running nicely already - but when I do I'll use these on that as well.


Obviously these are probably easier to obtain in the UK, but I do know you can also buy them in the US here for a reasonable price (for example, the Eezibleed is only $41.95 - much cheaper than the larger pressure bleeder mentioned above).

[PeteC]

I bought the Motive pressure bleader that Frank's picture shows. It works but is a hassle to use.

For my Mac trailer I have also used a vacuum pump system that sucks the fluid out. This system uses a high pressure air powered vacuum pump with a Mityvac type vacuum collection jar. I like this better than the Motive.

I recently bought an Oil-Boy oil extraction pump (vacuum system) from West Marine. I used it to extract the oil from my car that had a stripped oil plug that I could not remove. It worked great so I used it to extract the oil from my Honda outboard; worked great again.

I plan to try the Oil-Boy to suck the brake fluid out of the Mac trailer brakes the next time I change the brake fluid.

Because the trailer sits outside and the brake cylinder is somewhat exposed I plan to change the brake fluid every 2 years.

[Frank C]

I bought the Motive pressure bleader that Frank's picture shows. It works but is a hassle to use.

For my Mac trailer I have also used a vacuum pump system that sucks the fluid out. This system uses a high pressure air powered vacuum pump with a Mityvac type vacuum collection jar. I like this better than the Motive ...

Pete,
I'm curious why that Motive is a hassle to use?

Also, could you describe a bit more about the Mityvac system?

Thx!

[Chip Hindes]

So, it would appear nobody's gotten one of these to work satisfactorily on the Mac trailer.

The Titan master cylinder (pre'01 trailers) has a plastic screw cap ($7.50 from Champion) with a built in check valve, the purpose of which is to permit air to enter the cylinder as the fluid is depleted, while preventing the fluid from slopping out.

Although the check valve cap is at least theoretically designed to hold pressure, that pressure is typically very small, maybe a couple psi. Even if you discard the check valve parts and manage to seal off the cap vent and install a pressure fitting, the cap is thinwall plastic. The threads can't hold pressure, the silicone washer which seals the cap is not captive and there's no way any of these will hold 20 psi, as recommended in the bleeder guy's website, without blowing out.

That being said, if you can maintain it for awhile, it should only take a few psi to bleed the system, it will just take longer. If you have any pressure leaks you'll have to keep pumping up the system which pretty much defeats the purpose.

I've always told myself I should buy one of those caps and see what I could do with it, just never gotten around to it. If anyone's tried it I would be interested in hearing your thoughts.

Alternatively, it might be possible to buy or have made a metal or other solid material cap to which you could more easily install a pressure fitting and would be able to hold high pressure. I measured it and it appears to be 1 1/8-18TPI. Good luck.

[PeteC]

Frank,

The Motive has a cap or sealing plate that must be securely fastened to the master cylinder. 2 of these “caps” are shown in the picture you posted. Also shown is a plastic bag that holds 2 chains. The chain attaches to threaded j-bolts on one side of the cap, then wraps around the master cylinder and attaches to another j-bolt on the other side of the cap. You then tighten nuts on the j-bolt to snug the cap down on the master cylinder opening. Then you pump up the Motive bottle that contains new brake fluid. Then you open the bleeder valve at each cylinder and the old fluid is forced out and replaced with new fluid.

I find the setup clumsy. Also, you can wind up with a mess when you take the cap off the master cylinder.

Look at www.holeshot.com/old/ttools/brake_bleeder.html to see how the Mityvac system works. The handpump supplies vacuum to the reservoir jar, which in turn is attached to the brake bleeder valve. Open the bleeder valve and the brake fluid is sucked into the jar. You do need to keep an eye on the master cylinder to make sure you don’t suck it so low that air gets pulled into the line. I have found this setup easier and less messy than the Motive system.

I did a “Tim the tool man” enhancement by replacing the Mityvac hand pump with a
Harbor Freight vacuum pump.


I also use a mason jar with Mityvac caps for the reservoir.
www.mityvac.com/pages/products_a.asp
Part 06845 Mason Jar Kit

This setup has much greater speed and capacity – More Power arr-arr-arr-arr!

I just found that Mityvac now carries what looks like Oil-Boy pumps. Part: 07300 PneumatiVac

They also have a brake bleeder attachment. Part 07205 Brake Bleed Conversion Kit.

The Mityvac pumps are bigger than the Oil-Boy that I got (2.3 gallon vs 1.3 gallon).

I need to learn how to post pictures so I can show what I am talking about.

EDIT for Pete: "Quote" your post to see minor changes needed to embed the Air-Vac image.

[Frank C]

Regarding master cylinder cap:
Yes its true. You can use a late model GM master cylinder cap (Help! p/n 42035). You have to take 5 seconds to modify it but it works fine after that. What you will find when you open the package is that the GM piece has a little groove cut in the underside of it to relieve pressure!?! I don't know what the hull that's about, but take some black (or whatever) RTV and using a scrap of the original packaging, smear the groove full of RTV and let it cure for a bit.

Thanks, Pete! Yeah, that plate with chains around the cylinder ... strictly Rube! Apparently, the "inventor" is using a GM cap for his BMW. Maybe master cylinders only come in a few flavors? Anyway, he used RTV to defeat the General's air-bypass, and his GM plastic cap manages to hold 20 lbs.

Kevin's pressure bottle is interesting for using a tire's static pressure ... cuts the size of the pressure vessel by half, but also means the M.Cyl cap must hold 35 to 50 pounds of pressure. Seems that your vac system just needs to siphon from a large supply of fluid? ... feels like two-edges to this sword.

My Kodiak disc brakes arrived (silver-cad plate, $250 the pair). They are all impressively beefy items, the rotor/hubs, the calipers & the mounting plates. I'm still waiting for my disc brake actuator, the same model shown on Macgregor's current parts list (UFP A-60, $200). It includes an embedded backup solenoid. Once it arrives I'll see how feasible a pressure cap might be. If not, then your Air-Vac's next ... seems the capture vessel could be from ACE~! ... & completely skip the MityVac?

Maybe they should just sell the brake fluid cans with a couple of hose bibs out the top!