dodge_kid9712

hello all and thanks in advance for anyones help..heres the story

first the abs and brake light went on in the truck and i would notice when the brake pedal was depressed it was like there was no powersteering.. i ignored it but now i have read that the two work together so it now is a symptom of my brake problems...
the brakes would seem to tighten up somtimes while driving to where i barely had to press the brake pedal to stop...then when driven the next time it would feel normal and tighten up as driven...it would sometimes even feel like the brakes were on slightly with my foot off the pedal and having to drive against it...now one morning i get up and the truck has pretty much no brakes( pedal to the floor and it they barely work) with no abs/brake light. after driving it over to a shop the brakes start working fine again? does anyone know where to start? any help would be appreciated

Dave Miller

My 97 3500 has Hydroboost brakes as I assume yours does. I replaced my hydroboost about 2-3 years ago due to a leak. The hydroboost unit is mounted behind the brake master cylinder and the hydroboost unit is mounted to the firewall. There is no fluid connection between the brake master cylinder and the hydroboost but it is a physical connection.

The hydroboost has 2 hoses connecting it to the power steering system and thats how it gives you the boost to your brakes. When you press the brake pedal the linkage pushes a rod in on the hydroboost. On the other side of the hydroboost a rod pushes out into the brake master cylinder using the boosted power steering fluid lines to supply the power assist into the hydroboost unit.

I would look for leaks or low fluid in the brake master cylinder or power steering or lines. My leak was hard to determine if it was brakes or power steering fluid so I went to NAPA and put flourscent transmission dye in the power steering. The power steering was dyed slightly green so I could tell I had a power steering leak from the hydroboost unit. You can use a flourecent black light leak detecter also to view the dye.

If brakes and power steering are bad it could be your power steering system or the hydroboost unit.

Dave

Delectric

Dave is absolutely correct, the Hydroboost uses hydraulic pressure from the power steering pump to assist in braking. Because of the lack of vacuum in a diesel engine a power brake booster would not work well. A hydroboost has an accumulater on it in case of an interuption in hydraulic pressure because of stalling, broken belt etc. which will give you a couple applications on your brake pedal but that's all. If the Hydroboost itself isn't bad I would check your power steering pump too and the fluid level because you mentioned your steering felt as if the pump wasn't working. I would also just check the belt or maybe the tensioner if it is real intermittant. Just FYI, don't ever pour hydraulic fluid in your master cylinder, it's a quick way to ruin the rubber in your entire brake system. I don't know what year your truck is but a power steering pump on one of my 2003 3500's went south in about the first 20,000 miles after I purchased it. Don't know if it is a real common problem but could be.