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Discussion Starter · #1 ·
Ok so here we go. I've been beating my head against the wall for a week now trying to figure this out. A week ago I replaced the front pads and rotors on our 07 T&C. It has abs on the front and drums on the rear. I did everything as normal except when I compressed the piston on the caliper I forgot to take the brake fluid cap off and it blew off causing fluid to go everywhere. I went about the job as usual as I've done about 1000 brake jobs and have never once had this experience before. After I finished replacing the pads and rotors, I went to pump the brakes and had no pedal. With the van off I can stand on it and it won't budge. These are the things I have done to remedy this.

Replaced and bench bled the MC ( I thought I blew the seal after the cap incident. This was my initial thought). (No change)

Bled all the lines in the correct order 4 times. Twice with the vehicle off, twice with the vehicle on. ( I used the bottle and hose method each time using brand new fluid. No more air anywhere and no change to the pedal feel)

Made sure each one of the front calipers were making contact with the pads and retracting as usual and they were.

Clamped each one of the rubber lines one by one all the way around the van to see if it gave any change to the pedal. (none).

Checked the valve on the booster to see if I was still getting vacuum. (It was)

There are no visible leaks anywhere on the van at all. I have moved it to several different spots and pumped the brakes numerous times trying to find a leak that might have happened.

I just don't get it. These brakes were perfectly fine before I changed the pads and rotors. Our family drives it daily so replacing rotors due to warping is a normal thing about every 1/2 years. The only thing I can think of at this point is having the van plugged up and purging the abs system. Because maybe when I compressed the piston in the caliper it might of forced a little bit of air build up back through the system.

I'm sorry this post is long, but I wanted to be very thorough in my explanation that way you guys could give the best possible recommendations. I appreciate any response and thank you in advance.
 

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Welcome aboard,
What did the brake fluid look like initially when you bled the system?
What's the history of fluid service?

It sounds not as an ABS system problem but rather HCU problem. You can try performing ABS bleed procedure (if you can get access to capable scan tool) and if it initially improves but starts to degrade quickly, one of the valves/seals in HCU is leaking internally... If you're exceedingly lucky you might flush it out.

Also, FWIW, a warped rotor every 6 months does not sound "normal"
 

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Discussion Starter · #5 ·
Welcome aboard,
What did the brake fluid look like initially when you bled the system?
What's the history of fluid service?

It sounds not as an ABS system problem but rather HCU problem. You can try performing ABS bleed procedure (if you can get access to capable scan tool) and if it initially improves but starts to degrade quickly, one of the valves/seals in HCU is leaking internally... If you're exceedingly lucky you might flush it out.

Also, FWIW, a warped rotor every 6 months does not sound "normal"
The fluid was a little dark when I removed it. I've bled the system so many times now the fluid is fresh from the MC down to the calipers. And what is an hcu exactly? I know about the abs pump. I'm guessing it's something different from that? Also I do the rotors about every year and a half. This is our main family vehicle. Between me and my wife we have 6 kids. It's the only vehicle we have to titr them all around in. With that much weight in the van with breaking down hills and highways it's been about the norm for that timeframe. I'm literally reaching for anything at this point. I been beating my head off the wall for a week to figure this out..
 

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HCU = hydraulic control unit, the part behind CAB (ABS brain) - it has a number of solenoids, valves and pump motor is mated to it.
If you have a yard nearby and can score an exact same CAB/HCU on the cheap, that might be easier than looking for scan tool and trying to flush it out (which is not likely to solve it long term).

It's usually not air that gets pushed back into the system with caliper retraction, but rather sediment / dirt - it's always better to open the bleeder when retracting the caliper and adding some fresh fluid...
 

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Discussion Starter · #8 ·
HCU = hydraulic control unit, the part behind CAB (ABS brain) - it has a number of solenoids, valves and pump motor is mated to it.
If you have a yard nearby and can score an exact same CAB/HCU on the cheap, that might be easier than looking for scan tool and trying to flush it out (which is not likely to solve it long term).

It's usually not air that gets pushed back into the system with caliper retraction, but rather sediment / dirt - it's always better to open the bleeder when retracting the caliper and adding some fresh fluid
On top of the HCU, is there anything else that I could try that you can think of off hand? I'm gonna pick up a vacuum bleeder tomorrow morning and give that a go and see what happens. I don't think it can hurt at this point in time.
 

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Also, should I be bleeding the brakes with the van off or on? I've heard some ppl say on and off and I just want to make sure I'm going about it the right way.
It doesn’t make a difference if the van is on or off. With the bleeder valve open, the brake pedal should be easy to press even if the van is off (no power brake assist). I’ve done both ways and both are fine.
 

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Discussion Starter · #11 ·
Ok thank you, I've heard debates with it being on and off and it seems that it could go either way and ppl just seek for argumentative points when bored 😂 Any further input on my current problem at hand while your attention is on this thread? Lol
 

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I need some clarification from your initial post. You said that “I went to pump the brakes and had no pedal. With the van off I can stand on it and it won't budge.” Does this mean that the brake pedal goes to the floor with the van on, but with the van off the pedal doesn’t move at all? If so that could be a brake booster issue.
 

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Discussion Starter · #13 ·
I need some clarification from your initial post. You said that “I went to pump the brakes and had no pedal. With the van off I can stand on it and it won't budge.” Does this mean that the brake pedal goes to the floor with the van on, but with the van off the pedal doesn’t move at all? If so that could be a brake booster issue.
Yea so with the van off, it actually feels like idea of what everybody wants thier brakes to feel like. But I can hold my foot on the brake and turn the van on and my foot sinks with the pedal. It stays like an inch off the floor. It'll stop the car but it takes more pressure in which I can feel it bottom out when doing so. If I pump the brakes it'll build pressure a little bit and I can do a couple of rolling stops and then the pedal is back on the floor before Ive got to pump it up again. I've already replaced the MC and bench bled it. Bled every single line like 4 times already and I'm still gonna buy a vacuum bleeder tomorrow morning to try again. I'm just a stand still trying random **** at this point lol.
 

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Ok thank you, I've heard debates with it being on and off and it seems that it could go either way and ppl just seek for argumentative points when bored 😂 Any further input on my current problem at hand while your attention is on this thread? Lol
Haha no problem. I’m not the most knowledgeable guy here but I’ll try my best.

Common sense is telling me that if you pushed the caliper piston back and the fluid burst out of the master cylinder, that something else could’ve blew. It could be a line somewhere, or as another member posted it could be an issue with a module of sorts.

Keep an eye on the brake fluid for the next few hours or days. See if it drops because that means there’s a leak somewhere.

You could have gotten air into the abs module, which requires a scan tool to bleed. I tried an abs module bleed once and I heard the abs pump start buzzing away. I recommend obtaining or borrowing a capable scan tool to try this.

Maybe give it to a mechanic (might be cheaper to have them do it rather than buy a scan tool). At that point it might save you a lot of headache to get it diagnosed by a mechanic. I’d expect a diag to be around $150, give or take. Seems like you are handy enough to change the part once you know the problem. Good luck 👍
 

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Yea so with the van off, it actually feels like idea of what everybody wants thier brakes to feel like. But I can hold my foot on the brake and turn the van on and my foot sinks with the pedal. It stays like an inch off the floor. It'll stop the car but it takes more pressure in which I can feel it bottom out when doing so. If I pump the brakes it'll build pressure a little bit and I can do a couple of rolling stops and then the pedal is back on the floor before Ive got to pump it up again. I've already replaced the MC and bench bled it. Bled every single line like 4 times already and I'm still gonna buy a vacuum bleeder tomorrow morning to try again. I'm just a stand still trying random **** at this point lol.
Thanks for confirming. To me, this sounds like a brake booster problem. I remember reading somewhere that to pass a vehicle inspection, the brake pedal should be able to hold for a minute and it shouldn’t sink at all.

With the van off, the first few pumps of the pedal should feel normal but after 2-3 pumps it should get hard. That’s normal brake booster function. Being hard as soon as you turn off the van seems like an issue.
 

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Discussion Starter · #16 ·
Thanks for confirming. To me, this sounds like a brake booster problem. I remember reading somewhere that to pass a vehicle inspection, the brake pedal should be able to hold for a minute and it shouldn’t sink at all.

With the van off, the first few pumps of the pedal should feel normal but after 2-3 pumps it should get hard. That’s normal brake booster function. Being hard as soon as you turn off the van seems like an issue.
So if it means anything.. when I replaced the MC when I thought I blew the seals by pushing the old fluid back, when I pulled the MC off the booster there was a hard resistance to it and when I tilted the MC in a little bit of a left direction on the studs the vacuum suction broke. That's what the resistance was I was feeling. It sounded kind of like a poof lol..and I did check the valve on the booster to see if it was working correctly and it was.
 

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On top of the HCU, is there anything else that I could try that you can think of off hand? I'm gonna pick up a vacuum bleeder tomorrow morning and give that a go and see what happens. I don't think it can hurt at this point in time.
Bleeding the base hydraulic system seems like a waste of fluid and time, if the pedal is rock hard and not spongy with ignition off, there's no air in the system...
It might be worth doing the ABS bleed with DRB-III equivalent scan tool just to try to rule it out. IDK if bluedriver smart phone app can initiate ABS bleed, or if you can beg/borrow/steal a two way scan tool that's capable for couple hours.

It certainly won't hurt the brakes to bleed with vacuum, just stay under 15 inches. Likewise it's unlikely back pressure from pushing on caliper piston would cause any damage (it's pushing debris / contamination back up into the system that usually causes problems).

When the van is running, even though ABS is not actively pumping the brakes, it still tests the system and activates solenoids.
There's a specific service manual for the ABS system, you can find it here.
 

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Discussion Starter · #18 · (Edited)
Bleeding the base hydraulic system seems like a waste of fluid and time, if the pedal is rock hard and not spongy with ignition off, there's no air in the system...
It might be worth doing the ABS bleed with DRB-III equivalent scan tool just to try to rule it out. IDK if bluedriver smart phone app can initiate ABS bleed, or if you can beg/borrow/steal a two way scan tool that's capable for couple hours.

It certainly won't hurt the brakes to bleed with vacuum, just stay under 15 inches. Likewise it's unlikely back pressure from pushing on caliper piston would cause any damage (it's pushing debris / contamination back up into the system that usually causes problems).

When the van is running, even though ABS is not actively pumping the brakes, it still tests the system and activates solenoids.
There's a specific service manual for the ABS system, you can find it here.
That's what I don't get. All I did was change the pads and rotors. The van drove fine before that. Not after that. If back pressure from compressing the pistons on the calipers not create the issue because it's unlikely, then what the **** happened? Why would me installing brakes and rotors on the van, while not opening a single bleeder valve in the process, break something else way down the line that I didn't even touch? It doesn't make any sense. All I did was touch the 2 front wheels the entire time like the 1000th time I've done them..what makes this vehicle so dam different? It didn't happen 2 years ago when I replaced the same things the exact same way.. And if there is no air in the system because of a rock hard pedal with the van off then why would it go to the floor when the vehicle turns on? Are you telling me that that abs unit can hold that much air in it that it can make a difference in a foot and a half of pedal travel?
 

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Discussion Starter · #19 ·
I've seen some pedal travel because of air in my time of working on cars but nothing to this extent. I've experienced a ton of squishy pedals that still stopped a vehicle. But never have I had to continuously pump the brake to get a little bit of a pedal just to lose it after I come to a stop with that same pressure I built up, just to build it up again to do the same thing over and over again. And all that happening with no visual leaks of any kind or not loosing any fluid?? It has to be something so stupid that I'll want to punch myself in the face when I find it. But this is why I'm here. So more experienced ppl can help me figure it out. Sorry for my rambling and frustration. This van is just getting to me 😂
 

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Ok so here we go. I've been beating my head against the wall for a week now trying to figure this out. A week ago I replaced the front pads and rotors on our 07 T&C. It has abs on the front and drums on the rear. I did everything as normal except when I compressed the piston on the caliper I forgot to take the brake fluid cap off and it blew off causing fluid to go everywhere. I went about the job as usual as I've done about 1000 brake jobs and have never once had this experience before. After I finished replacing the pads and rotors, I went to pump the brakes and had no pedal. With the van off I can stand on it and it won't budge. These are the things I have done to remedy this.

Replaced and bench bled the MC ( I thought I blew the seal after the cap incident. This was my initial thought). (No change)

Bled all the lines in the correct order 4 times. Twice with the vehicle off, twice with the vehicle on. ( I used the bottle and hose method each time using brand new fluid. No more air anywhere and no change to the pedal feel)

Made sure each one of the front calipers were making contact with the pads and retracting as usual and they were.

Clamped each one of the rubber lines one by one all the way around the van to see if it gave any change to the pedal. (none).

Checked the valve on the booster to see if I was still getting vacuum. (It was)

There are no visible leaks anywhere on the van at all. I have moved it to several different spots and pumped the brakes numerous times trying to find a leak that might have happened.

I just don't get it. These brakes were perfectly fine before I changed the pads and rotors. Our family drives it daily so replacing rotors due to warping is a normal thing about every 1/2 years. The only thing I can think of at this point is having the van plugged up and purging the abs system. Because maybe when I compressed the piston in the caliper it might of forced a little bit of air build up back through the system.

I'm sorry this post is long, but I wanted to be very thorough in my explanation that way you guys could give the best possible recommendations. I appreciate any response and thank you in advance.

The hidden issue that I’ve been having and seeing read up this Aly is that the main line coming off of the brake booster vacuum line was cracked or the seal wasn’t great and then under heavy load I noticed it was occasionally popping off future reference just replace the main brake booster vacuum line
 
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