Do I remove and keep the calipers upside-down when replacing brake fluid?

[Antipodes4WD]

I have no record of the brake fluid ever changed, so it was the time. After watching countless Youtube videos I settled on the vacuum pump method. Strangely enough, only a single line goes to the rear axle and another to front brakes. I always thought ABS works on individual wheels...

The available videos are either a disassembly, or just adding liquid to the master cylinder and sucking from bleeding screws.What worries me is that (especially at the front calipers) the bleeding screws are at the top. I see no way the old fluid will leave the caliper's cylinders to be replaced with the new fluid. Likely the fluid in those cylinders is as old as the car. Even if I hold the caliper with the bleeding screw down I am not sure it will help. The proper job would be disassembling the line and draining the caliper.

Am I missing something?

 

[Shayne]

Long time ago I decided to replace brake fluid on a 90 series , i just opened all the bleed nipples until they dripped and kept topping up the reservoir until the full bottle was gone .

Then bled like usual .

 

[Towpack]

I changed the brake fluid using one of those pressure bleeders (Gunsons I think) that pushes fluid through from the reservoir rather than sucking it through from the caliper end. I've never actually split a caliper but I assume they are designed so the fluid flows through the entire caliper before exiting the nipple. I've even bled the system dry by blowing air through from the reservoir, followed by new fluid and the system bled easily so, in answer to your question, I don't believe it's necessary to remove the calipers to bleed out all the old fluid.

 

[Antipodes4WD]

I changed the brake fluid using one of those pressure bleeders (Gunsons I think) that pushes fluid through from the reservoir rather than sucking it through from the caliper end. I've never actually split a caliper but I assume they are designed so the fluid flows through the entire caliper before exiting the nipple. I've even bled the system dry by blowing air through from the reservoir, followed by new fluid and the system bled easily so, in answer to your question, I don't believe it's necessary to remove the calipers to bleed out all the old fluid.

Yeah, I think that comes to the definition of the 'replace brake fluid' in the Toyota Land Cruiser 'Warranty and Service' manual. What is seen on the Youtube is mixing old and new brake fluid (and if I flush a gallon through the system mostly new) down the pipes and calling it done.

If I read the ellery.com.au manual (a physical book), they also have 'Brake fluid replacement' chapter page 261. They go into trouble of bleeding dry the master cylinder, holding calipers upside-down, removing cylinders.. etc.

If I have to follow Toyota schedule of every 24 months and do it at the workshop manual suggests, perhaps I start looking for an electric vehicle option... But as the mainstream Youtube goes it is clearly a half-arsed job.

Some suggest that 'In Toyota we trust' and the caliper chambers are designed to be flushed in the process, but I have serious doubts about that.

 

[Shayne]

ABS is electric when it sees one wheel lock up it reduces braking on all 4 to prevent you losing traction .

 

[Towpack]

I'm inclined to trust the Toyota FSM rather than any third party workshop manual.

 

[uHu]

Good point, Antipod, especially for the 4-pot calipers.
As water, and any particles dissolved in water, gathers at the bottom; and that both the inlet and the bleeder are at the top of the inner chamber of the caliper; there must be a bit of crud left over at the bottom after a normal, thorough bleeding.
I see that the bottom pistons corrode faster, or more often, than the top pots; which I take as an indication of more water at the bottom. I think I change three bottom pistons for each top one when servicing calipers.
Otoh, it takes only a few minutes extra to block off the hose, remove the caliper completely and drain it, before putting it back on for a normal bleed through.

 

[Shayne]

If the truck is new to you then its worth pointing out that despite not feeling it necessary rebuilding all 4 calipers on all three of my cruisers resulted in a significant improvement .

Mind you i replaced all the discs with M-Tek drilled and slotted at the same time .