BLEEDING

[rickeieio]

So today, I filled the master cylinder with the appropriate fluid and tried to bleed my brakes using a vacuum system which pulls fluid through the caliper. Or, it's supposed to work that way.  I finally succeeded in getting clear fluid into my catch bottle, but it was a pain.  One wheel done, I hope.

My question is: how is the proper way to bleed a BluDot/Hyd system?  I'm gonna guess you should have someone in the truck pumping the brakes while I crack the bleeder nipples, just like in the old days.

Taking each wheel off to access the bleeders is a bit of a nuisance.

[GlennWest]

I use a bleeder system. Bottle with hose in it. Put fluid in to cover tube in bottle, hook you to bleeder. Pump brakes a few times. Check bottle. When fluid clear in hose, it is done. Close bleeder. May have to empty bottle before finished.

[NoDirectionHome]

Vacuum bleed exactly as you did is the most efficient way to bleed hydraulic brakes.  You of course must monitor the master cylinder to never uncover the port.

[HERO Maker]

Another great way is to hook up a line to the master cylinder fill area to a pressurized bottle of fluid, then open up each of the bleeder valves, one at a time, from front to rear, and it will be done!

Yes, all wheels have to come off, and you must remember to bleed both sides of the caliper.   So if you just use your Big Foot, or even Lippert leg system to lift trailer, it really goes fast.  I would still have someone pump the brake pedal, but may not be needed.  I don't remember well when my friend did mine.

[GlennWest]

Mine working great and only used top bleeder.

[gjhunter01]

Quote

 

I just suck out and replace the brake fluid in the reservoir and doing this 2-3 times over a couple week period will gets 85% of the fluid replaced. I know that bleeding the brakes is the best method, but changing the reservoir fluid is a whole lot easier. The brake fluid will thoroughly mix in the brake system contrary to what some people may claim.

[rickeieio]

Tried pressurizing the master with a kit my brother loaned me.  There was no cap in the kit that would work on my master.

I found only one bleeder on each wheel.  The line goes to the top of the inboard side of the caliper, then another line connects the bottoms of each side of said caliper, with the bleeder on top of the outboard side.  Looks like a good way to trap air in the inboard side to me.

In theory, all I would have needed to do was fill the new master with fluid and let the air in the short new hose rise to the top.  But I thought this would be an excellent time to flush as well.

As for lifting the coach, I don't have a fancy hydraulic system.  I'm using a bottle jack under each axle, one at a time.

[adept99]

Rick,

Hook your hand pump up to the main line from the master cylinder (you'll have to disconnect it) and pump fluid through the entire system. You may need to use a different pump (Pressure vs Suction) and adapt the hose to the brake line, but I know that will work.

Need a hand?

Paul

 

[Ronbo]

On 12/16/2017 at 4:56 AM, rickeieio said:

I found only one bleeder on each wheel.  The line goes to the top of the inboard side of the caliper, then another line connects the bottoms of each side of said caliper, with the bleeder on top of the outboard side.  Looks like a good way to trap air in the inboard side to me

Wow, I don’t see how you can get 100% of the air out of that caliper. Poor design. I guess you could lay it on the side with the bleed screw up and gravity bleed the system. 

[Alie&Jim's Carrilite]

26 minutes ago, Ronbo said:

Wow, I don’t see how you can get 100% of the air out of that caliper. Poor design. I guess you could lay it on the side with the bleed screw up and gravity bleed the system. 

The Kodiak calipers on our DRV only have 1 bleeder.   

[HERO Maker]

That's why you will need someone pumping your brakes on the truck.  That pressure will blow any tiny bubble out of your line.  The smallest of bubbles will expand when heated and that will cause your brakes to start dragging.  I don't need to tell you that though.

For everybody else, hook a small clear line to that bleeder and into a clear jar.  Open the bleeder valve while starting to pump the brakes until no more bubbles, close the bleeder valve while still pumping and move on.

[GlennWest]

One can pickup a bleeder kit most any parts house. Think Wally world has it too. Bottle with magnet, clear tube. 

[rickeieio]

I think I have the line bled, though I know the other 5 calipers are not flushed.  I need to do a few other things to the trailer so I can get it out of the shop, as I need the space for other jobs.  The fluid I purged out of the system was not as dark as I'd feared, indicating it wasn't 10 years old.  Someone had flushed this system before we bought the coach.

[Jack Mayer]

Generally I do it the way Rocky described. On Dexters you have the poorly designed "two bleeders". Kodiak's do not. 

On initial installation it is CRITICAL to get all the air out. I really mean that....or you WILL have brake overheating problems, and ineffective brakes. IMO, you MUST flush/bleed the master cylinder(s) on the bench first. Doing them in place is far more difficult. Then after installation I usually charge the system with regular brake fluid, then run a racing fluid of a different color through to ensure I get ALL the air out. You may not have to go to all this trouble (and some additional expense). But I've learned over time doing this, that this is really the only way I can GUARANTEE that I'll get all the air out.

On a changeover, just use a different color fluid and follow Rocky's method. 

[GeorgiaHybrid]

Jack,

One thing to watch for when using racing brake fluid. DOT 3 fluid can be replaced with DOT 4 fluid (not the other way around though) and DOT 5.1 is compatible with DOT 4. However, a LOT of racing brake fluids are DOT 5 which is silicone based (all of the others are Glycol based). DOT 5 is a performance fluid with extremely high boiling points compared to Glycol based brake fluid but the seals are made from different material and those fluids are NOT compatible with each other.

I would urge everyone to make sure that the fluid they use is compatible with what they have. In most cases, after a few years of use, the older fluid will have a noticeable color change (yellowish) from new fluid which is normally clear and it makes it fairly easy to see when the old fluid is gone. I prefer a vacuum bleeder but others prefer a power bleeder, that is personal preference but it is a LOT easier to use either one of those systems than the old "pump it up and bleed it down" system that takes two people.

[rickeieio]

Thanks for the clarification on fluid types.  I thought that 3 or 4 could be interchanged.  In fact, I have several motorcycles which call for DOT 3/4 fluid.  So far, I've never owned anything using DOT 5.  Well, I guess the Buell did.

Dad had a simple way of bleeding, which I'll likely do when I do a complete flush:  He kept a clean pump oil can, and used it to power bleed from the wheel cylinder.  You need to evacuate the master occasionally, but it's simple and works.  Go to a farm supply store and buy syringes intended to give large animals shots, to suck out the excess fluid.  

I think I know where that old oil can is hiding..............

[Jack Mayer]

Dave that is a good point on the fluids that I should have mentioned. You do have to make sure you use the right one.  And you can usually see the difference in the color of really old fluid. The critical factor is to get the air out....and it is not always easy.

[rickeieio]

18 minutes ago, Jack Mayer said:

. The critical factor is to get the air out....

So true.  Thus my intent to push the old out from the wheel towards the master.

For an exercise in futility, bleed dual disks on a vintage motorcycle.  They will make you pull your hair out.