so, as is i'm sure is the case with most everyone, failing brakes scare me alot - especially since my emergency brake can barely hold the truck still on a hill.

i had a single strange symtom a few weeks ago and posted to an old thread about it, but now there's another symptom that is relatively unrelated. i'm happy to do preventive maintenence on the brake system, just not sure where to start.

symptom 1: when parking in tight parking lots (i.e. lots of turning and lots of braking), its happened twice that my brakes have become super-stiff such that i nearly have to stand on the pedal to get the truck to stop. they go back to normal pretty quickly, though.

symptom 2: i've noticed my dashboard brake light staying on somewhat past when i release the parking brake for a while, but just the other day i noticed it come on after it had been off for a while and without me touching the parking brake. first time it happened, i jiggled the parking brake with my foot and the light went off. this happened again yesterday on my way home from work, but i did an additional experiment with the truck in park and the parking brake off. i pumped the regular brake several times, and sure enough, the brake light came on for about 5 seconds, then went out. tried it again and the same thing happened.

so my question is: could these be general symptoms of not enough vacuum to the brake booster? i didnt realize the dash brake light actually monitored the regular (hydraulic) brakes. also, my brake fluid is topped off on the master cylinder, so no issues there.

some additional, possibly related symtoms are that i think i've noticed my steering getting just slightly tigher lately. (power steering pump reservior is full)

could a bad idler pulley or tensioner arm on the belt cause these symptoms. my tensioner arm does 'tick-tock' a slight bit back and forth at idle. nothing crazy, but a consistent back and forth (or maybe up and down, i forget) motion.

is there anything else i can do or check before i just go order a new idler, tensioner and belt? then its a new vacuum pump if that doesnt do it. any likelihood its something else like a dying steering pump, water pump, alternator causing the problems?

any vacuum hoses that are prone to cracking and leaking?

any suggestions are much appreciated.

 

I honestly believe you need to check your brake fluid.the level may be at the threshold where when u pump it the level drops enough to make the light come on.rear brake adj. Being loose could provide enough space for the fluid to drop thus switching the light on.or just the e/brake switch needsa bit of adj.
The other,I bet you have a faulty or failing vaccum pump.IF all accs are still tight and belt is good,and not noisy.

 

that's a good point about the fluid going down after pumping the brakes. i'll have to check that. however, that would be a ton of fluild going elsewhere in the system as i'm pretty darn sure the reservoir is filled to the top.

if it doesnt turn out to be that, i'll probably just add a vacuum pump to my idler and tensioner order and check all the other components real good with the belt off to be sure that's not the source of my problem.

i've had power brakes fail on other vehicles and been OK, but this truck is much heavier than them and i'm afraid it'd take miles (or a guard rail or the rear end of another car) to stop if the power goes out on the brakes at speed. highway wouldnt be bad. coming up to an intersection would be real bad.

another minor detail of the symtoms is that the pedal is high when it gets real stiff, not on the floor like its bottomed out in the cylinder due to low fluid...

 

I agree, maybe your vacuum pump is going south.

VACUUM PUMP IN-HG AND kPa VALUE

17-21 in-Hg is what my book shows =57-70 kPa
At idle below 10in for more than 7 seconds will illuminate the brake lamp.
Most vac leaks i have found have been at the heat/ac control.

BTW if you sit pumping the breaks you can deplete the vac and set the lamp.

Second I also think that you have to adjust the rear brakes or maybe change the shoes.

 

thanks for the specs. i'll have to find/borrow a vacuum gauge to check. i was thinking i could just set up a water manometer to do it, but a quick google conversion of inHg to inches of water tells me my water manometer would have to be 300" tall! that's alot of vacuum these pumps make!

 

It could also be bad connections / hoses /clamps at the booster or the Manifold....but most likely you need a new pump....

 

My vac pump went out pulling my 5er, scared the crap out of me. My wife asked me why I was standing up trying to stop. There is a vac line, a white one, under the hood on the passerger side up in the corner by the windshield. Its happened to a lot of folks and that is the hood hinge rubs that vac line and wears a hole in it. Check it.

 

will do! this is the little stuff that i'd like to check for before going and replacing the pump. thanks!

 

I had a broken vacuum line up there. . But I think it was black white inside. I never had any brake issues though. I fixed it. Nothing seemed to change.

 

Have someone watch the reservoir and pump your brakes till they are tight, if you lose a lot of fluid, I'd pull the rear tires and check the pads and clearance, adjust if needed.

Whens the last time the brakes have been bleed?

I was having brake issues, and found a broke cable on the adjuster on the rear passenger side. Self adjusting it helped for a little while, but still was having brake issues, with random brake light coming on. When I did my rear-end swap and got the rear adjusted right, and then bleed the brakes, my truck has never felt better while stopping.

 

very good to know - i had a vw beetle back in high school with manual shoe adjusters - man those suckers were a pain to keep in adjustment. not hard, just a pain to do every month or so...


since posting this thread, i've been reading about the hydro-boost conversion mod, and thinking of going that route if my vacuum pump is the culprit - especially since my vacuum brake booster does have a little rust on it. i should make sure all the slave cyliners are in order though, before giving the master more assist or it could be instant failure somewhere else...


thanks again guys.