IDI vacuum pump junk
i ain't rite
Joined: Mar 2005
Posts: 65,492
Likes: 5,552
From: Marlboro Mental Hospital.
this is true because when i 1st start up my truck thats all that it has until higher rpms are reached, i want to split it for more brake reliability and to test the brake booster. i might have replaced my vac pump when it didnt need it as a result of a leaking booster but im not hearing any hissing sound from the booster so i dont know if it has a leak or not??
read vacuum. you should have at least 19 inches instantly. if not, the pump is bad.
Mountain Pass
Joined: Apr 2021
Posts: 144
Likes: 16
From: Fratt, TX
thanks the 19in is what i need to know, gonna borrow my neighbors vacuum gauge tomorrow to check if its still good(its only like 3 months old!! got it from NAPA)
Fleet Mechanic
Joined: Sep 2016
Posts: 1,519
Likes: 224
From: Nevada
I have been having brake problems with the 86 for quite a while now. One time it would stop ok,
then the next time it would be like pushing on the floor. Or have brake pressure, and second application...nothing.
I put it into a shop to have them go through everything. Rotors, Drums, Pad Shoes, Hoses etc...all good.
Leave the shop, get down to Hwy 395 and like pushing on the floor.
Finally used the vac gauge, and indicated the Vac Pump, so replaced it....and the brakes seemed oooook. But then
eventually back to the same pushing on the floor feel.
I did notice the HISSSS sound coming from under the dash when pushing the Brake Peddle, seemed to come from
where the rod goes into the Booster. Was told that was normal.
Finally bought about 8ft of Vac hose from O`Reilly. Disconnected the vac line to the round plastic ball and other electric
gizmo on the pass fender. That Vac line plugs into the plastic manifold on the Fire Wall that other vac lines connect to.
The Vac line from the Vac Pump Connects to this Manifold, then goes to the Brake Booster. Also another one the runs to
the vac controls under the Dash.
The Vac line that ran to the plastic ball, connect it to the new Vac line from O`Reilly and run it over to the driver side and
stick it through the hole in the FW where all the wires and Spedo cable go through. Pull enough in side and connect you
Vac Gauge. Then you can see what is going on. I used the Gauge from HF.
Mine showed 20HG on the Gauge, but applying the Brakes it would really drop. I usually just put a slight drag on the
Brakes when coming to a stop, might back off, then apply again...and nothing. Holding the Peddle down, the Pump didn`t
seem to build up the vac on the gauge. Release the Peddle, the needle would drop, then build back up to 20HG.
Finally went to O`Reillys and bought another Booster. When I got it replaced and took her for a run, damed thing scared
me it stopped so quick. I have never had Brakes work this good in the 7 years I have owned this thing.
I told the guy at O`reillys when I ordered it the year and model, and said over 8600lbs. The one I get is 10" wide, I figured
maybe an up grade. But actually a single Diaphram Booster and for 7000lbs and under. Also the MC won`t bolt to it.
The one for my 86 F250 is 8" across and a Double Diaphram. So check the numbers and have your info before hand.
I have a couple Vacuum Pumps I got from PNP with good strong Vacuum. along with bracket and pulley.
Around $30 ea.
Charlie
then the next time it would be like pushing on the floor. Or have brake pressure, and second application...nothing.
I put it into a shop to have them go through everything. Rotors, Drums, Pad Shoes, Hoses etc...all good.
Leave the shop, get down to Hwy 395 and like pushing on the floor.
Finally used the vac gauge, and indicated the Vac Pump, so replaced it....and the brakes seemed oooook. But then
eventually back to the same pushing on the floor feel.
I did notice the HISSSS sound coming from under the dash when pushing the Brake Peddle, seemed to come from
where the rod goes into the Booster. Was told that was normal.
Finally bought about 8ft of Vac hose from O`Reilly. Disconnected the vac line to the round plastic ball and other electric
gizmo on the pass fender. That Vac line plugs into the plastic manifold on the Fire Wall that other vac lines connect to.
The Vac line from the Vac Pump Connects to this Manifold, then goes to the Brake Booster. Also another one the runs to
the vac controls under the Dash.
The Vac line that ran to the plastic ball, connect it to the new Vac line from O`Reilly and run it over to the driver side and
stick it through the hole in the FW where all the wires and Spedo cable go through. Pull enough in side and connect you
Vac Gauge. Then you can see what is going on. I used the Gauge from HF.
Mine showed 20HG on the Gauge, but applying the Brakes it would really drop. I usually just put a slight drag on the
Brakes when coming to a stop, might back off, then apply again...and nothing. Holding the Peddle down, the Pump didn`t
seem to build up the vac on the gauge. Release the Peddle, the needle would drop, then build back up to 20HG.
Finally went to O`Reillys and bought another Booster. When I got it replaced and took her for a run, damed thing scared
me it stopped so quick. I have never had Brakes work this good in the 7 years I have owned this thing.
I told the guy at O`reillys when I ordered it the year and model, and said over 8600lbs. The one I get is 10" wide, I figured
maybe an up grade. But actually a single Diaphram Booster and for 7000lbs and under. Also the MC won`t bolt to it.
The one for my 86 F250 is 8" across and a Double Diaphram. So check the numbers and have your info before hand.
I have a couple Vacuum Pumps I got from PNP with good strong Vacuum. along with bracket and pulley.
Around $30 ea.
Charlie
Mountain Pass
Joined: Apr 2021
Posts: 144
Likes: 16
From: Fratt, TX
I have been having brake problems with the 86 for quite a while now. One time it would stop ok,
then the next time it would be like pushing on the floor. Or have brake pressure, and second application...nothing.
I put it into a shop to have them go through everything. Rotors, Drums, Pad Shoes, Hoses etc...all good.
Leave the shop, get down to Hwy 395 and like pushing on the floor.
Finally used the vac gauge, and indicated the Vac Pump, so replaced it....and the brakes seemed oooook. But then
eventually back to the same pushing on the floor feel.
I did notice the HISSSS sound coming from under the dash when pushing the Brake Peddle, seemed to come from
where the rod goes into the Booster. Was told that was normal.
Finally bought about 8ft of Vac hose from O`Reilly. Disconnected the vac line to the round plastic ball and other electric
gizmo on the pass fender. That Vac line plugs into the plastic manifold on the Fire Wall that other vac lines connect to.
The Vac line from the Vac Pump Connects to this Manifold, then goes to the Brake Booster. Also another one the runs to
the vac controls under the Dash.
The Vac line that ran to the plastic ball, connect it to the new Vac line from O`Reilly and run it over to the driver side and
stick it through the hole in the FW where all the wires and Spedo cable go through. Pull enough in side and connect you
Vac Gauge. Then you can see what is going on. I used the Gauge from HF.
Mine showed 20HG on the Gauge, but applying the Brakes it would really drop. I usually just put a slight drag on the
Brakes when coming to a stop, might back off, then apply again...and nothing. Holding the Peddle down, the Pump didn`t
seem to build up the vac on the gauge. Release the Peddle, the needle would drop, then build back up to 20HG.
Finally went to O`Reillys and bought another Booster. When I got it replaced and took her for a run, damed thing scared
me it stopped so quick. I have never had Brakes work this good in the 7 years I have owned this thing.
I told the guy at O`reillys when I ordered it the year and model, and said over 8600lbs. The one I get is 10" wide, I figured
maybe an up grade. But actually a single Diaphram Booster and for 7000lbs and under. Also the MC won`t bolt to it.
The one for my 86 F250 is 8" across and a Double Diaphram. So check the numbers and have your info before hand.
I have a couple Vacuum Pumps I got from PNP with good strong Vacuum. along with bracket and pulley.
Around $30 ea.
Charlie
then the next time it would be like pushing on the floor. Or have brake pressure, and second application...nothing.
I put it into a shop to have them go through everything. Rotors, Drums, Pad Shoes, Hoses etc...all good.
Leave the shop, get down to Hwy 395 and like pushing on the floor.
Finally used the vac gauge, and indicated the Vac Pump, so replaced it....and the brakes seemed oooook. But then
eventually back to the same pushing on the floor feel.
I did notice the HISSSS sound coming from under the dash when pushing the Brake Peddle, seemed to come from
where the rod goes into the Booster. Was told that was normal.
Finally bought about 8ft of Vac hose from O`Reilly. Disconnected the vac line to the round plastic ball and other electric
gizmo on the pass fender. That Vac line plugs into the plastic manifold on the Fire Wall that other vac lines connect to.
The Vac line from the Vac Pump Connects to this Manifold, then goes to the Brake Booster. Also another one the runs to
the vac controls under the Dash.
The Vac line that ran to the plastic ball, connect it to the new Vac line from O`Reilly and run it over to the driver side and
stick it through the hole in the FW where all the wires and Spedo cable go through. Pull enough in side and connect you
Vac Gauge. Then you can see what is going on. I used the Gauge from HF.
Mine showed 20HG on the Gauge, but applying the Brakes it would really drop. I usually just put a slight drag on the
Brakes when coming to a stop, might back off, then apply again...and nothing. Holding the Peddle down, the Pump didn`t
seem to build up the vac on the gauge. Release the Peddle, the needle would drop, then build back up to 20HG.
Finally went to O`Reillys and bought another Booster. When I got it replaced and took her for a run, damed thing scared
me it stopped so quick. I have never had Brakes work this good in the 7 years I have owned this thing.
I told the guy at O`reillys when I ordered it the year and model, and said over 8600lbs. The one I get is 10" wide, I figured
maybe an up grade. But actually a single Diaphram Booster and for 7000lbs and under. Also the MC won`t bolt to it.
The one for my 86 F250 is 8" across and a Double Diaphram. So check the numbers and have your info before hand.
I have a couple Vacuum Pumps I got from PNP with good strong Vacuum. along with bracket and pulley.
Around $30 ea.
Charlie
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