I have a 1997 Dodge Grand Caravan 3.3L with 165,000 miles. Love my van. It runs great! Recently, I've been having a funny thing happening with my brakes. My pads were getting low and I noticed that at speeds greater than 40 mph the breaks would work normally. Once the van down shifted the pressure would release and I would have to press the brake in slightly more to get the van to stop. I thought this was because of the low front pads so decided to change the pads (same pads I've been using for years, lifetime pads from Autozone). Started the van and got almost no pressure even after pumping the brakes for a bit so I bled the brakes (in proper sequence). So, now the problem is slightly worse then before.

The van still stops but there seems to be less pressure. Originally, I thought it was the master cylinder (165k) going out but I'd like to exhaust any other options before I go that route. Other symptoms I've noticed...if I'm doing 60 mph on the freeway and have to make a quick stop I get really good braking like nothing's wrong. Once the rpm's drop though that pressure slips a bit. Also, at a complete stop, I'll notice the pressure slip. But, if I release the brake then engage again, I get good pressure.

Any suggestions would be appreciated.

Michael

 

Make sure you have no leaking fluid at anyof the brakes. With the van off and applying firm pressure to the pedals does the pedal leak down over a minutes time? After this pressure test is a good time to look for seepage from rear cyclinders or lines. If you find none, then I would look into having the ABS bleed procedure done by a shop with the proper equipment (this is not a homeowner procedure) Good luck

 

After doing 60mph you would have a high sorce of vaccum,more so than at idle. Vaccum line in good shape? Brake booster does not sound like it's leaking at idle. Again sounds like air in system. Did this come on all at once? Used up pad's can come close to draining the brake resavor(sp) allowing air in system. Brake fluid checked. This along with the post above.

 

Thanks All for you responses. Yeah, I may have let the brake reservior get low and this problem hit pretty sudden. Didn't know that would let air in the system. How much should I expect to pay for a COMPLETE bleed and refill of brake fluid?

 

if you got air in the system and you have abs brakes you need a scan tool to cycle the abs unit to bleed system properly

i cant see them charging more than an hour's labor for this
but i can see them trying to get you to replace parts that may not be needed
got to a garage you trust that has a scan tool if needed(abs) and a vacuum bleeder system

 

MCF,

Does your brake pedal goes all the way down after a few brakes?? If it happen it is the master cylinder .

If you have air in the brake line you will loose preasure from the begining.

 

Bought a 32 oz bottle of Preston synthetic brake fluid to refill system and bled the brakes until near clear fluid was coming out. Back driver's side was giving me problems. After first bleed on rear driver side, the brakes would lose all pressure. Would have to hit it just right when doing that side to get pressure. Went ahead and finished all four then took it for a spin. Same problem!

Called around to see if anyone had diagnostic tools to hook up to the ABS. One mechanic couln't get me in until next week. The other could see me today but said that his tools don't work on Dodges (???). Said only a dealer could connect to the ABS.

On the ride to the mechanic my breaks got more and more pressure. By the time I got there, my breaks were near perfect!!! My wife insisted they look at them anyway so I was convinced to let them adjust the rear breaks (not sure what all is involved in that). The mechanic there said that there probably was NOT air in the ABS. He said the breaks would act more erratic trying to adjust to the air.

He lifted the rear end and spun both tires. The rear driver tire (the one that gave me problems earlier) spun freely while the other didn't. While pulling off the rear driver drum (thought I had rotors back there) drum had a serious lip, pads were extremely low and cylinder had a small leak. He said this could be what's wreaking havoc with the ABS and that I would need pads, turn drums, new cylinder, and hardware kit (not sure what that last thing is).

I'm excited that the breaks are working fine right now. I'm hoping it's not temporary. We've been thinking of using the van as a trade in at a dealer so let's hope the breaks hold up til then.

Any ideas what all is going on here?

ps. Realized that air in the system could've come from low reservoir from slow leak or from cranking the caliper piston back in place without opening the bleeder valve.