My 94 dodge 2500 is loosing power brakes. They are fine when driving for the first pump or two but as soon as you start just idling along in traffic ect you loose the power brakes. (Still plenty of brakes but you really have to stomp on the pedel) The brake and abs light comes on at the same time. Its a real pain when trying to manuver the truck into a tight spot. The brakes and lights go off as soon as you let the truck sit for 30+ seconds idling or as soon as you hit the throttle coming off and idle. I Think its either the brake booster or vacum pump any ideas?
Evan

 

Yikes, thats scary. I have the opposite problem, mine constantly lock up and the truck skates around.
Id try to see if you have leaks first, look for fluid on the frame especially behind the tank.
Then Id check the vacuum pump. pull the hose off the vacuum pump and put a vacuum gauge on it you should see something like 25 inches of vacuum.
Then id look to see if your master cylinder is leaking.
You might want to change the fluid completely with a flush and bleed from all four wheels to get any water or air out of the system. Dark brown brake fluid is a sign of corrosion / contamination.
If you live in the rust belt those bleed screws will not be easy to get out and will likely snap. Try heat and a hand-held impact driver. Do yourself a favor and put some grease on the threads before you button everything up.

 

Very common problem, the vacuum pump just can't keep up when idling and braking. Nothing is broken, just a bad design.
Besides throttling up the other solution is adding a vacuum storage tank.
Dodge sells a kit just for the problem but it's over $100. All you need is vacuum tank and a little hose teed into any place in the vacuum system. Tanks are availible aftermarket for around $25 or you can make your own with 12" of 4" PVC pipe with two caps glued on and a port drilled and tapped into it. Hard part is finding a place to mount it. The dodge kit mounts to the side in the front of the coolers on the radiator mount.

 

if its a known problem do you think the vacum pump is just getting weak and the tank is a band aid fix? I know the brake system has no leaks. I might try to put new fluid in it tom night. However I think the problem goes deeper than that because of how intermittant it is and you still have brakes its just you get an extremly hard pedel
Evan

 

my brakes were acting funny a while back and the abs and brake light would come on as well.... the problem.... vacuum leak in a couple spots. luckly the two spots both broke off near the connectors in the line so i just stuffed them back in there and wrapped them up good with some electrical tape. works great for me... just a thought

 

I have the same problem on my '95 with my brakes...work fine, but when parking & using them "more"...the pedal gets stiff, etc.
I'm going to go with the additional vacuum canister myself to see if that helps/fixes the problem.

FWIW I tied into one of the smaller vacuum lines w/my canister, & it didn't help at all. I'm told that it has to be tied into one of the larger (1/2" I believe) lines.

What all is in the $100 Dodge repair kit ??

 

I agree with Infidel, it's a vacuum problem. My 96 does it too, when I am backing a trailer, and using the brakes a lot. If you don't have enough vacuum, when you check it, you might be able to save a few bucks by getting a vacuum pump here:
http://www.fixinrams.com/

He sells the seal kit, but I don't see any total rebuild kit for the vacuum pump internals. You'd probably have to do an exchange with him.

Chris

 

My trucks both have done it since brand new, sort of doubt it's a worn out pump. My feeling is the only reason Dodge changed to the hydro assist system in '97 was to avoid this problem.


Another fix I've heard of people doing but don't have personal experience with is adding a Ford electric vacuum pump to the system.
They are under $100, very reliable and put out the same amount of vacuum no matter what the engine rpms are.

 

I don't want to steal ur page but just a quick ?. on my 1993 250 cummins truck the brake petal will loose a huge about of pressure with the power brakes and will drop very far down then the brake and abs light come on. When I turn it off and pump it a few times the pressure builds back up and the lights will go off after I start it up again. As soon as I hit the brakes they come right back on. I also notice when i took off the main vacuum hose to booster oil started leaking out from the vacuum pump. Pump goin out?