Vac. Pump + Brake Question

[1992camarors]

Ok I just purchased my truck and I have a few things missing under the hood. I scored this thing for $400.00 so I expected some problems. But the problem is that I have absolutly no brakes. The pedal just depresses with very little resistance. I hear this hissing sound when I do this, I think it is comming from the brake booster. But there is a vac nipple on the brake booster with nothing hooked to it, so I looked around and there is no hose anywhere near there to be hooked up too. But then I saw the vac. pump on the left side of the engine with no hose on its nipple either. My first thought was that there should be a vac hose running between the two. Am I right?

This is kinda off the subject but my friend and I tried to get it to run today and it was cranking. But the batteries were new in 2005 from Napa. They were still dead so we jumped them. My car on one and my friends on the other. Was this ok to do? I mean the truck was turning over very slowly and all the lights were coming on.

 

[KR69IDI]

You are correct on the vac hoses. I don't see why the jump start situation would hurt anything.

 

[1992camarors]

Well I heard somewhere that you had to cross the cables? I mean my freind has a 97 Bravda and he put his on the main battery and Me with my 90 Cadillac Fleetwood on the secondary battery on the right side.

Ok I got another question. It says on my truck Hi Output on the heater box. And also the higher hoserpower sticker is stamped on my left valve cover. What exactly does my engine have better to make it have more power?

 

[KR69IDI]

Not real sure what you mean with "cross the cables"?

Your High Output, is only a factory tweaked inj pump. There are no other changes with the IDI's. What HP is yours set at? It should show on the sticker.

 

[1992camarors]

Its says 175 BHP on the sticker. Ok got another qustion. I have another missing hose for a device on the left side of the engine bay. Its round and has a sensor at the end of it. Its mounted right infront of the main battery.

 

[KR69IDI]

I think you mean right behind the battery, on the left side if your looking at the engine from the grill. I believe that it is the vacuum switch for the brake warning light on the dash, if we are talking about the same sensor.

 

[argve]

with no vacuum assist then your brake pedal should be hard as a rock - I suspect either you have no brake fluid, major leak or master cylinder is toast because you aren't building any pressure in the system.

Since you mention that the vacuum pump isn't hooked to anything then your floor defrost selection won't work because the flaps are controlled by vacuum.

The sensor on the passengers side is as said the brake light sensor - when vacuum is not pulling enough it will kick on the brake light on the dash to warn you.

 

[1992camarors]

Well I know there isn't any fluid in it right now. But the brake light does come on and stay on when I turn on the ignition. So the hose should go from the vac. pump then there should be a T in the line for one going to the sensor and the other going straight to the brake booster? Is that right? If there is a diagram I would greatly appreciete it.

 

[1992camarors]

Here is a picture of the sensor I'm talking about.

 

[JPR]

that is the low vacuum switch. It is one of things that will activate the brake warning light.

As said before, no vacuum would not cause the pedal to go to the floor, it would just mean no power brakes. I suspect the master cylinder is bad. If you find the master cylinder is bad and lots of fluid has gotten into the vacuum booster, you may want to consider switching to a matching year F450 hydroboosted brake booster and master cylinder. There is very detailed write up by Monte in the idi tech articles. The only difference on my installation was to use the Edelmann hoses 71416 and 71442 which fit without modifications.

 

[towcat]

someone went through alot of trouble cleaning the engine compartment. what does the rest of the truck look like? If you were the one who cleaned it, do change your oil soon. there's a rubber grommet in the valley pan that does a very poor job keeping water out of the crankcase.

 

[LUCKY_LARUE60]

Wow the motor bay looks great. Wish mine looked as good.

Jim

 

[1992camarors]

Yeah I know the master cylinder is bad, but what I want to know is where does the hose go to after it comes from the vac. pump??? Does it go straight to the brake booster or what?

 

[diesel4me2]

wow nice engine bay, the hose you are refering to should go to a vacum tree on the fire wall, perty much in line with the pump. look at the pump, look up at the fire wall. thats where mine is. the tree splits the hose to run your low vacum switch, air, cruise, brake booster, and all your vents in the dash. if you don't have those acceseries just connect to what you have. if there is no tree, i've found them at junk yards, i've also seen them at places like autozone although there only the 3 port style. hope this helps.
chris

 

[cleithau]

That engine looks amazing for a $400 truck.

Where in the valley pan is the rubber grommet? I changed my fuel line from the filter to the IP and got some fuel in the valley pan. It was all towards the back of the engine.