Bubble after 2 hours of bench bleeding MC.

[ET]

Hey folks.

I've finally got to bleeding the brakes. I started w/ blench bleeding new mc. It's leveled, 3/4" slow stroke with about 15 seconds wait in between. I got the front reservoir bleed fine but I keep getting one bubble on the release stroke on the rear reservoir. I did this for about couple of hours and gave up. I tried tilting the mc front high then rear high to try getting the air out. No change. I tried both tubes from ports to the reservoir and also plugging the ports. No Change. That one bubble only come out at the rear/bigger hole/port in that reservoir and only on the back or release stroke. Any ideas? Should I just leave it?

Uh, Pushing in on the mc is pretty firm.

Thanks,
Eugene

 

[broncnaz]

It could be air getting in from the rear seal since its only one bubble and you cant get it to go away I'd just install the MC and bleed the rest of your brakes it should work out fine.

 

[Socal Tom]

I agree, its probably just sucking in a little air from the tubing or something. I'd install and go with it.
Tom

 

[ET]

Thanks guys. I'll mount it and finish bleeding the rest.

Eugene

 

[Apogee]

When you have the ports plugged, you should only be able to stroke the piston ~1/8" give or take. Any more and you can be fairly sure that you still have air in the MC. I've had some bench bleed in 5 minutes or less and others take about an hour, so long that I was wondering it the unit was bad. It can sometimes help knock hard to bleed air bubbles loose if you tap on the MC with a mallet or soft hammer while stroking the piston.

 

[ET]

Yes. I did tap on the mc while pushing. I found a post earlier that suggested and tried it. Still that one bubble. I don't know maybe the mc is bad. The stroke is firm but I think I can bottom the piston if I wanted to when the ports are plugged. It's just odd. I couldn't find a helper to do the rest of the system so I can't tell how firm the peddle is.

Eugene

 

[jetsg4]

if you can't find a helper, do a search for the solo bleed plan. i've never done it, but it involves a bowl full of oil and a hose....

 

[ET]

I bought a self bleed kit a few years ago and it didn't work very well. I'd tried gravity bleed but it took way to long. Grand daddy coming Tuesday and he's going to give me a hand. Thanks for the suggestion.

Eugene

 

[Pa PITT]

I Like to flle the m/c ...put the 2 rubber hoses fed back into the cyl..pump until bubbles stop ...My other method is to fill it up... crack the line ...Pass side rear ..and go get a beer let it set there and drain every one in a while I add some more fluid ...
....2nd My Bronco needs a close Eye on it fluid good brakes but after about 2 mouths one side or the other will be empty so keep an eye on it ...easier than fixing what you can't find