Bleeding Mast Cylinder in the car, Suggestions, Ideas, Don't do that's Options

[hndyhrr]

Got the MC installed, all lines attached.

Watched Ian Karr's video.


Started to bleed, seeing old brake fluid and lots of bubbles, after about fifteen minutes of this I am not seeing a stream of fluid coming down the clear plastic tube. Yes the end is submerged in brake fluid. Checked for leaks at the MC and dry as a bone. Check inside car and dry also.

I have never done this before so just wondering and asking for suggestions, ideas and don't do that.

Thanks

Renee

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[DennisV]

I have never done this before so just wondering and asking for suggestions, ideas and don't do that.

I recently did this for the first time. We did it the old fashoined way with one in the car pumping the brake, and me at the bleeders. We had a completely new system (master cylinder, hard lines, hoses, calipers). It took a lot of time. More than you would think.

Perhaps obvious, or not since it's your first time:
1. Make sure you don't let the master cylinder reservoir go dry, or you will have to start over.
2. Start at the caliper farthest away from the master cylinder and work your ways closer. (Passenger rear, driver rear, passenger front, driver front).

[hndyhrr]

I have never done this before so just wondering and asking for suggestions, ideas and don't do that.

I recently did this for the first time. We did it the old fashoined way with one in the car pumping the brake, and me at the bleeders. We had a completely new system (master cylinder, hard lines, hoses, calipers). It took a lot of time. More than you would think.

Perhaps obvious, or not since it's your first time:
1. Make sure you don't let the master cylinder reservoir go dry, or you will have to start over.
2. Start at the caliper farthest away from the master cylinder and work your ways closer. (Passenger rear, driver rear, passenger front, driver front).

Did you bench bleed the Master Cylinder? Or bleed MC in the car. I though MC had to be bled first and them move on to the bleeding all 4 calipers?

[infraredcalvin]

Using a motive power bleeder? I’ve never had to separately bleed the MC or proportion valve. I do it a bit different, but not so much.

When replacing a caliper or MC, i go though this process:

Fill power bleeder with 2 liters of fluid (or more if you take it slow), pressurize and open all bleeders. Close them off one by one (bottom then top on each caliper) as bubbles stop at the caliper (I go closest to furthest). You’ll need to keep pressure up on motive watch fluid level. Once all are closed off, go around and tap all calipers, MC, and P-valve with rubber mallet. Then bleed one by one, bottom then top bleeder, furthest from MC to closest i tap the caliper with the mallet as i do this.

[rjames]

I couldn't get the air out until I replaced all of the bleeder valves with speed bleeders.

Try the long hose method. Attach a hose at the bleeder valve and then run it back to the reservoir. Makes it a one person job. You can sit in the car, pump the brakes and watch the lines to monitor when the bubbles are gone. Plus you don't waste any fluid because you're routing it back to the reservoir.

[Jack Standz]

Except for DOT 5 (which is silicone-based), brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This property can lower the fluid’s boiling point, leading to issues like brake fade and reduced performance under high temperatures. Water in your brake fluid also promotes corrosion.

As a regular part of maintaining your 914, you should flush your brake fluid to address this issue. So, you should avoid recycling old brake fluid into the reservoir during the bleeding or flushing process as the water present in your brake fluid will not get purged.

+1 on the Motive bleeder and there are YouTube videos that document how to use one. Works well and you can bleeder your 914's brake system without a second person.

[flxzcat]

Try the long hose method. Attach a hose at the bleeder valve and then run it back to the reservoir. Makes it a one person job. You can sit in the car, pump the brakes and watch the lines to monitor when the bubbles are gone. Plus you don't waste any fluid because you're routing it back to the reservoir.

Smart!

[rjames]

Except for DOT 5 (which is silicone-based), brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This property can lower the fluid’s boiling point, leading to issues like brake fade and reduced performance under high temperatures. Water in your brake fluid also promotes corrosion.

As a regular part of maintaining your 914, you should flush your brake fluid to address this issue. So, you should avoid recycling old brake fluid into the reservoir during the bleeding or flushing process as the water present in your brake fluid will not get purged.

+1 on the Motive bleeder and there are YouTube videos that document how to use one. Works well and you can bleeder your 914's brake system without a second person.

Agreed.
My suggestion of connecting the bleeder hose back to the reservoir assumes all the old fluid has been removed first.
Many a home mechanic like myself have wasted a decent amount of new fluid just trying to get the air out of the system. Routing the bled fluid back to the reservoir not only reduces waste, but also keeps you from having to refill the reservoir during the bleeding process.

[porschetub]

Except for DOT 5 (which is silicone-based), brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This property can lower the fluid’s boiling point, leading to issues like brake fade and reduced performance under high temperatures. Water in your brake fluid also promotes corrosion.

As a regular part of maintaining your 914, you should flush your brake fluid to address this issue. So, you should avoid recycling old brake fluid into the reservoir during the bleeding or flushing process as the water present in your brake fluid will not get purged.

+1 on the Motive bleeder and there are YouTube videos that document how to use one. Works well and you can bleeder your 914's brake system without a second person.

Agreed.
My suggestion of connecting the bleeder hose back to the reservoir assumes all the old fluid has been removed first.
Many a home mechanic like myself have wasted a decent amount of new fluid just trying to get the air out of the system. Routing the bled fluid back to the reservoir not only reduces waste, but also keeps you from having to refill the reservoir during the bleeding process.

(IMG:style_emoticons/default/agree.gif) bought a kit just for the job (not Motive ) and it is so good on my other cars also , cheers.

[VaccaRabite]

I like to use a motive to keep the reservoir full. But I don't think you can pressurize the system enough with it to get the stubborn bubbles out.

So I double up. I have someone stomping on the brake pedal even with the Motive bleeder hooked up.

Start with the rear pass bleeder. Then rear driver. Then front pass. Then front driver.

You will get the most air out of the rear pass bleeder.

Zach

[GeorgeKopf]

I just installed a completely new (and dry) brake system. I was struggling with getting the master cylinder to pull fluid from the reservoir so I took the bare end of my ShopVac hose (blowing air) and held it against the opening of the fluid reservoir and applied positive air pressure.

That did the trick and I was able to bleed the brakes after that.

Four obvious things:

1. I covered the entire fender and frunk area with towels in case it splashed.
2. Hold the hose tight against the reservoir opening and then turn on the ShopVac.
3. Make sure you switch the hose to blow air.
4. Leave the right rear bleeder screw open.

George