Brake fluid flushing questions! Reservoir ran dry!

[Volf]

Still have the car up on jack stands doing all that fun new car maintenance. Threw on new rotors, pads, and rebuilt all 4 calipers last night. Long story short, I wasn't able to completely finish the job last night. I left the car with the calipers hung up by safety wire and the brake lines snug, but not tight (I thought). Came out today to finish up and got everything installed and bolted up and opened up the brake fluid reservoir and it was empty!? Checked around and sure enough one of the calipers wasn't completely snug and it all ran out during the night.

The brake side of the reservoir (furthest from the firewall right?) was bone dry, I could see the filter down in the bottom. The clutch side (closest to the firewall) was right at the minimum mark but had fluid in it.

I filled it with ATE Super Blue DOT 4 fluid and hooked up the pressure bleeder. Bled the brakes normally minus the passenger rear caliper, the bleed screw is clogged so I ordered a new one. The rest of the calipers threw a lot of air initially but then the fluid changed color and no more air and bled like normal.


How screwed am I from running dry? If I remember right running dry can cause issues with the ABS? When I filled the reservoir it didn't take a whole bunch to fill it up, maybe between a half cup and 1 cup of fluid.

I want to get all the fluid out of the system. The fluid would make any maintenance geek vomit a little bit. So I want to get it out of the clutch system as well. Do I just hook up the power bleeder and open the bleed screw on the slave cylinder and wait for color change? How do I get the fluid out of the master cylinder?


Sooner I get this done the sooner I can do the power steering flush, coolant flush, trans flush, diff flush, and switch this beast over to German castrol!


Thanks in advance!

[das borgen]

LOL

same EXACT thing happened to me last winter when I rebuilt my calipers

what did I do?

I buttoned everything and then I filled the reservoir

then I went and opened all the bleeders and closed each one as soon as gravity managed to get fluid to come out from each, I would close them one by one (adding fluid to the reservoir as needed, of course)

then I took a power bleeder to the master cylinder and pressurized to 15psi.... I then bled the system 2 complete circuits over (right rear, left rear, right front, left front)

now go forth and enjoy your brakes!


for good measure, I bled my clutch....... but it wasn t needed.............


how well did it work? after my 4th track day (and maybe 8 autocrosses) 8 months later (last month), I bled my brakes for the hell of it and did not see a single bubble

edit: on VWs, it says that if you run your MC dry, you must cycle the ABS module before you bleed so I asked around a lot and people told me for BMW it was not needed....if you're worried about it, I m sure there's a way to cycle the ABS by jumping the ABS relay or something...maybe this thread can help

[RRSperry]

You are probably fine.

Bleeding the cluch slave also pushes new fluid in the master.

If it were me, I'd finish up, go for a drive, and find a place to engage the ABS a few times just to cycle the ABS controller, and then go beeld them again.

[Volf]

Good to know the ABS isn't FUBAR. After I get my new bleed screw I'm going to re-bleed the whole system again and bleed the clutch.

[Patrón]

You are probably fine.

Bleeding the cluch slave also pushes new fluid in the master.

If it were me, I'd finish up, go for a drive, and find a place to engage the ABS a few times just to cycle the ABS controller, and then go beeld them again.

good advice

Good to know the ABS isn't FUBAR. After I get my new bleed screw I'm going to re-bleed the whole system again and bleed the clutch.

[GotBHP?]

Nothing wrong with letting the system run dry, how do you think they filled it at the factory in the first place? Just bleed all the air bubbles away.

[trahsub]

Good to know the ABS isn't FUBAR. After I get my new bleed screw I'm going to re-bleed the whole system again and bleed the clutch.

As you probably know, the service depts have the ability is pulsate the ABS system, which in theory is supposed to finish the bleeding job up to 100%. Many of us don't have any issues with this, however given the season (IE Autumn), what I've done is found some wet leaves in a parking lot and done some low speed lock ups so the ABS system triggers nice and easily. Then I'll head back to the garage for one more bleeding session, but honestly, I don't think I even remember seeing any add'l air bubbles come out. Just a thought.

[Fallinggator]

There is definitely something wrong with letting the system run dry. Try not to say things like that when you apparently have no idea what you're talking about. It could result in a rather costly mistake for someone in both time and money. As for how do I think they fill it at the factory... I think they do what is called a bench bleed where they bleed the MC before installing it, or in the owner's case uninstalling & then reinstalling it after a bench bleed. Also, for some of the more complicated new systems they use a piece of machinery that costs about $13,000 to do so. Not exactly in the price range of your average DIY mechanic. Granted, in most situations you can get away without having a piece of equipment like that, but not all. Either way, you're still going to need to bench bleed the system to get it right. Absolutely best case scenario, and luckiest, is that you at least have to bleed the entire system several times, and hope that it will fix the problem. It definitely won't always work, and brakes are an area that I like to do right... which means a bench bleed.

Nothing wrong with letting the system run dry, how do you think they filled it at the factory in the first place? Just bleed all the air bubbles away.

[mitch500]

There is definitely something wrong with letting the system run dry. Try not to say things like that when you apparently have no idea what you're talking about. It could result in a rather costly mistake for someone in both time and money. As for how do I think they fill it at the factory... I think they do what is called a bench bleed where they bleed the MC before installing it, or in the owner's case uninstalling & then reinstalling it after a bench bleed. Also, for some of the more complicated new systems they use a piece of machinery that costs about $13,000 to do so. Not exactly in the price range of your average DIY mechanic. Granted, in most situations you can get away without having a piece of equipment like that, but not all. Either way, you're still going to need to bench bleed the system to get it right. Absolutely best case scenario, and luckiest, is that you at least have to bleed the entire system several times, and hope that it will fix the problem. It definitely won't always work, and brakes are an area that I like to do right... which means a bench bleed.

7 year old thread from the grave


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[hc1001]

There is definitely something wrong with letting the system run dry. Try not to say things like that when you apparently have no idea what you're talking about. It could result in a rather costly mistake for someone in both time and money. As for how do I think they fill it at the factory... I think they do what is called a bench bleed where they bleed the MC before installing it, or in the owner's case uninstalling & then reinstalling it after a bench bleed. Also, for some of the more complicated new systems they use a piece of machinery that costs about $13,000 to do so. Not exactly in the price range of your average DIY mechanic. Granted, in most situations you can get away without having a piece of equipment like that, but not all. Either way, you're still going to need to bench bleed the system to get it right. Absolutely best case scenario, and luckiest, is that you at least have to bleed the entire system several times, and hope that it will fix the problem. It definitely won't always work, and brakes are an area that I like to do right... which means a bench bleed.

Not sure if you took him literally but i do not think he meant running the brake system dry as in a car running without any brake fluid. He meant letting the brake system empty when its not running.

There is nothing wrong with flushing the brake fluid from the car. As long as its replaced and all the air is removed from the system prior to running the car. You will need diagnostic tools to cycle the ABS pump.

And yes, this is a very old thread.

[AJLM34A]

You will need diagnostic tools to cycle the ABS pump.

I rebuilt all 4 calipers, replaced the 6 brake lines, and the brake system went dry. I did not need to use a diagnostic tool and cycle the ABS pump to bleed the system.

[RRSperry]

You didn't need too, but that is the "correct" way to do it... I've got a GT1 so I can cycle the ABS, but rarely do...

[kevinwilly]

I've had various e36's bone dry at LEAST half a dozen times over the years and never have needed to cycle the ABS to get all the air out. I always bleed everything 2 or 3 times just to be sure, but that's more because I absolutely HATE spongy brake pedals.

There are other models of cars when an ABS cycle is absolutely necessary. And there's SOME cars that you can use the ABS system as a power bleeder, which is especially nice. But e36's are pretty chill.

[hc1001]

I rebuilt all 4 calipers, replaced the 6 brake lines, and the brake system went dry. I did not need to use a diagnostic tool and cycle the ABS pump to bleed the system.

Hi AJLM, i never said you need it to bleed the brakes. I said you need the software to cycle the abs pump. There is a way to jump the abs or asc relay to activate the abs pump but not sure if its doing the same as the software.

Its needed to remove air if you replace the abs pump or to flush old fluid out from the abs pump.
If you dont introduce air to the abs pump or slave cylinder, you dont need to cycle/bleed them but i was referring to a complete dry system or flushing all the old fluid out and getting new fluid in. You have to activate the abs pump for it to pull new fluid and push out the old/air.

I am also not saying you must and absolutely need to do this. The system will feel spongy if there is air in it and thats fine but the correct procedure is to cycle the abs pump.