hydroboost air bubbles?

[K5dreamer]

hey all, im lookin at an M1009 that has had a blown brake line and several lines replaced. the current owner says there is a brake line on, and the brakes are "soft" for a while until pressure builds up, im not familiar with the hydroboost system, but it sounds to me like the system just wasnt bled proporly.

granted internet diagnosis is kinda like the special olympics, but in ya'lls opinion do you think that this is a problem that could be solved with having the brakes bled, or does it sound like there is a more serious problem.

Thanks in advance.

 

[broc944]

What does he mean by the pressure building up? Like pumping the pedal a couple times?

 

[K5dreamer]

no just kinda like after a certain ammount of time passes (not sure exactly how long, maybe a minute or so) the system pressurizes enough that the brakes are nice and firm. but right after starting the engine the brakes are soft.

also he says that the engine has a hard time starting when its cold, and he has to press the gas pedal a bit to get it started, but once it fires up it runs fine, and in warmer weather it dosnt mis a beat. does that sound like bad glow plugs, maybe dirty injectors? i know small block chevy's up down back and forth, but im kinda new to this diesel thing.

 

[jp0863]

the hard start is more than likely an injection pump, but could be several things. mine does that when it is warm, but fires right up when cold.... as far as the brakes go, i would guess it wasnt bled right...

 

[dremu]

no just kinda like after a certain ammount of time passes (not sure exactly how long, maybe a minute or so) the system pressurizes enough that the brakes are nice and firm. but right after starting the engine the brakes are soft.

also he says that the engine has a hard time starting when its cold, and he has to press the gas pedal a bit to get it started, but once it fires up it runs fine, and in warmer weather it dosnt mis a beat. does that sound like bad glow plugs, maybe dirty injectors? i know small block chevy's up down back and forth, but im kinda new to this diesel thing.

Sounds like glow plugs, yeah. Good luck getting the old ones out, hope they aren't swollen too much That and make sure the batteries are GOOD. When mine were weak they'd crank the starter okay but couldn't cook the glowplugs in the cold. Got me some big 1100CCA group 31P's and solved that problem

-- A

 

[K5dreamer]

i was guessing the glowplugs needed replacement, according to the seller he just put two new batteries in it. might just have to factor new glowplugs, injectors, and a pump into the price of purchase.

 

[diesel4me]

I have a master cyliner that has a blown seal in the rear brake portion of it in my 82 K20 with a 6.2--the brake fluid drips onto the ground if I fill the rear chamber!..but it still stops decent (with front brakes only mostly,since the rears only work as long as there is fliud in the chamber)..but I don't have to wait for "pressure" to build,or pump the pedal,the brake pedal is "low",but the amount of effort I apply never changes..(and I'm replacing the master soon,and have not been driving it far or very often like this! --that big red "BRAKE" light is highly annoying after dark,and several near collisions are not good for my heart..)

I'd guess the P/S pump might be weak if you don't get good power assist right away,or maybe some hoses to it or the hydroboost are mushy inside and restrict the flow sometimes..or the "fliud" might be contaminated ,or replaced with thicker stuff to help hide leaks or other problems..(a friend bought an Isuzu that had "Lucas" in the P/S pump rather than P/S fluid--and it was "stiff" after a cold start for several miles,until it thinned out--then it felt normal)...

I have to push my gas pedal to the floor, or at least 3/4 throttle to start mine up--it cranks much longer before firing if I dont!..my glow plugs were dead when I bought my truck,only 2 still worked!..cost about 70 bucks for 8 new AC G60 glow plugs..

I think I may have a few weak or dead ones already too--I start it up a lot cold,and lately its been taking longer,and I have to leave them "energized" longer to start it..they also look like they have been there 20 years already,I just put them in in Dec '03!..rotted to death!..one of the originals wont come out,and I'm not going to force it too--I'd open up a big can of worms trying to extract the broken tip out,the injector lines are kind of rusty,and most likely wont survive being removed.. .

 

[K5dreamer]

yeah ive found all the dealerships near the seller, and ill be calling them on my lunch break tomorrow to find a specialized diesel tech to check the truck over, and ask the seller to drop it off before i come out. if he has a problem, ill have to ask why he would be against it. but i dont think he will.