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Discussion Starter · #1 · (Edited)
94-97 PSD Vacuum Pump Replacement Instructions

I recently bought my first Powerstroke, a 97 F250 4x4, and some problems came up that I was not sure how to fix. This is for the vacuum pump..

I was driving down the road on my way to school and the brakes went out when I was going down a hill. The pedal was stiff; I could not depress it. Also, the brake light came on. When I got the vehicle to stop, I inspected for leaks and made sure there was fluid in the master cylinder. I was stumped because it did not act like air in the lines or a master cylinder.

I didn't know that there even was a vacuum pump, let alone that it would have any effect on the brakes. I did some searching and found that this was probably the issue: It was.

I could not find any good info on how to perform the replacement. All of the info that I found was either incomplete, vague, or for the IDI 7.3 and passed off for a Powerstroke.

I made this instruction set for a class and figured I would post it here for those of us who are not well versed in Powerstrokes yet. Hope it helps.

Tell me if you cannot read the file.

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I am not sure how to post the pics to the forum, if you need the pics they are in the file I attached.

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Vacuum Pump Replacement Procedure
For a 1994.5 to 1997 F250/ 350 7.3L Powerstroke

Contents
Tools needed 3
Introduction 4
Part I - Job Preparation 4
Part II – Pump Removal Process 5
Part III – Pulley Removal/ Installation Process 8
Part IV – Pump Installation Process 9
Part V –Vehicle Operation Restoration 10
Part VI – Function Check 10
Troubleshooting 11



Tools needed
• 10mm wrench
• 15mm socket
• ½ in. wrench
• Breaker bar
• Slotted screwdriver
• Channel locks
• Pulley puller/ installer
• A platform to stand upon in order to reach inside the engine compartment
CAUTION: Be aware of your surroundings and remember to watch your step when working in elevated positions.
Note: Additional tools may be needed in the event that a unique situation presents itself.



Introduction
The vacuum pump operates the brake system. The brake warning light will come on in the event that the pump is malfunctioning and not creating enough vacuum pressure. The operation of the brake system will become impaired, and it will be almost impossible to depress the brake pedal. Due to the hazards of working in the engine bay, simple preparations can be made to reduce the risk of being injured. The procedures in Part I are done in order to help ensure your safety.

CAUTION: These repairs are not intended for everyone. This instruction set is designed for those who possess moderate mechanical skills, understanding, and experience.

Figure 1: Brake warning light, located on dash below tachometer

Part I - Job Preparation
1. Park vehicle on a level surface, turn off engine, set parking brake, and pull hood release
2. Open the hood, disconnect the two batteries by removing both negative battery terminals using the ½ inch wrench. After they are disconnected, move the battery cables out of the way so they do not contact either of the battery terminals or any metal surfaces.


Figure 2: Engine compartment, component locations

Part II – Pump Removal Process
Step 1 - Serpentine belt removal
1. Using the breaker bar and the 15mm socket, place the socket on the serpentine belt tensioner pulley nut and rotate the tensioner arm counter-clockwise. When the arm is rotated far enough, the serpentine belt will become loose enough to pull off of the alternator pulley.

Note: The fan blades are unevenly spaced: Rotate the fan out of the way to the large gap between the fan blades. This will allow enough clearance so the belt tensioner can be worked on; if this is not done, when the belt is removed from the belt track and the tensioner is allowed to rotate back to rest, the tensioner will rotate further than when the belt was engaged and the tool will be jammed into the fan.

Figure 3: Location of serpentine belt tensioner components

2. Maintain pressure on the belt tensioner. Slip the serpentine belt off of the alternator pulley. Allow belt tensioner to slowly rotate into its rest position.
Advice: To allow easier installation of the serpentine belt: Do not fully remove the serpentine belt from the vehicle. Only remove it from the belt tensioner, top idler pulley, alternator, air conditioner, and vacuum pump pulleys. Keep the belt in place on the hard to reach components on the lower part of the engine.

Figure 4: Removal of belt from alternator pulley


Step 2 – Pump removal
1. Remove the hose clamp on the vacuum pump side of the vacuum hose, using channel-locks, for a ‘spring type’ hose clamp, or a screwdriver or an appropriate socket for a ‘screw type’ hose clamp
2. Remove the vacuum hose from the pump
3. Using the 10mm wrench, remove the 10mm bolts securing the pump to the engine, there are three.

Advice: If available, a stubby ratcheting wrench will expedite the removal of the vacuum pump bolts.

Note: The bolts will not come out of the pump mount due to clearance issues with the pulley.
4. Remove the vacuum pump from the vehicle

Figure 5: Vacuum pump components

Part III – Pulley Removal/ Installation Process
Step 1 - Pulley removal
1. Remove the pulley from the vacuum pump, using the pulley puller/ installer tool (not all pulley puller/ installer tools work in the same way, use the tool according to manufacturer’s instructions)
2. Remove bolts from old pump



Step 2 – Pulley installation
1. Install bolts in the bolt holes on the new pump
Note: If the bolts are not installed before the pulley, you will have to remove the pulley again so they can be installed. The bolts do not have enough clearance to fit in behind the pulley.
2. Press pulley onto new pump, per the manufacturer’s instructions


Part IV – Pump Installation Process
Step 1 – Pump installation
1. Install the pump: the bolt holes will line up only one way to prevent misalignment
2. Attach the pump hose, using the original hose clamp, to the vacuum pump

Figure 6: Vacuum pump components


Step 2 – Serpentine belt installation
1. According to the serpentine belt diagram, located on the core support and in Figure 7
WARNING: Ensure the belt is not misaligned or it may jump off track and cause injury or damage vehicle components. The groves of the belt should seat onto the ridges of the pulleys, and vice versa.

Figure 7: Serpentine belt diagram sticker


Part V –Vehicle Operation Restoration
Reconnect the negative battery terminals to restore your vehicle back to operating condition.


Part VI – Function Check
1. Remove all tools from engine compartment.
2. Keep the parking brake engaged
3. Keep the hood open
4. Start the vehicle and allow it to run long enough for the vacuum pump to build pressure, about 30 seconds. The brake warning light should be illuminated momentarily and then go out within 30 seconds.
5. Check brake pedal pressure. The brakes should have returned to a ‘normal operating feel’; they should depress steadily, and after a few compressions, be difficult to press.
6. Look in the engine compartment. Ensure the serpentine belt is engaged correctly.
7. If the brake system seems to be operating normally at a standstill, shut the hood.
8. Get in vehicle, disengage the parking brake, and slowly move the vehicle forward and backward a few feet, ensuring you have adequate brake pressure.
9. If the vehicle stops properly, take it out onto the roadway for a test drive.
10. If the vehicle operates properly during the test drive, the process is complete.

Troubleshooting
Vehicle won’t start:
Ensure batteries are connected.
Vehicle will not pull out:
Ensure the parking brake is disengaged.
Clunking sound:
Inspect fan and serpentine belt.
No brakes, hard brake pedal:
Check to make sure the vacuum hose is connected to the vacuum pump. If it is you may have a faulty new pump. Check the vacuum pressure with a vacuum test kit.
No brakes, soft pedal:
If the vacuum pump is producing sufficient pressure, check the master cylinder for brake fluid, check for leaks, there may be an additional brake problem. If there are no leaks and fluid is present in the master cylinder, the brake booster or the master cylinder could be bad.
Note: There are other brake issues that could result in loss of operation. If these common culprits are not the cause, seek professional assistance.
 

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Wow... this is a big help thank you thank you thank you!
Josh
 

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Great post. I had to figure it out as I went along the first time as well. We bought the gear puller instead of renting it. So far we have done 2 or three this year.

If you stay with powerstrokes remember that certain model years do not have a belt driven vacuum pump. The brakes get hydraulic pressure from the power steering pump. Vacuum is provided by and electric vacuum pump over the right fender well.

Good job man.

Oh... BTW the van body is extra fun to work on. There is little to no room. Add in the ambulance prep package with dual alternators and the the belt routing is even more fun.
 

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Let's see, my memory is bad. I know they began with the 99 F (truck) and E (van) bodies had the hydroboost brakes. I am sure other's on the forum can tell you which production month Ford began the switch.

I know they went back to a belt driven vacuum pump in the E bodies with the 6.0L engine
 

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In obs powerstrokes only the f-superduty had hydroboost brakes
 

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So is it safe to use an after market replacement vacuum pump for this or is it best to stay with Ford? I know on certain parts it is best to stay with Ford and others it makes no difference and you can save money. Just wondered where you purchased your replacement vacuum pumps and if there is a core charge. Thanks!
 

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Discussion Starter · #11 ·
I got mine at AutoZone. They have 5 different ones for my year, ranging from $115 to $250 or so. No core charge. It has a life time warranty. You have to pull the pulley off of your old one and install it on the new one. They rent the puller there, you front the money for the tool and get a full refund when you bring it back.
 

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I got mine at AutoZone. They have 5 different ones for my year, ranging from $115 to $250 or so. No core charge. It has a life time warranty. You have to pull the pulley off of your old one and install it on the new one. They rent the puller there, you front the money for the tool and get a full refund when you bring it back.
Awesome, thanks klm! Do you think the issues I have listed below would be the vacuum pump or brake booster or both? I appreciate the help!


Blinker and Brake Pedal RPM Jump...Vacuum Pump? Baffled
I have read other users post on here that when their vacuum pump goes out the pedal becomes really hard to press. Well my brake light is coming on and the pedal will push fine the first pump then hardly nothing on the second pump and then hard as a rock like a block of wood under it and will barely stop the truck on the third pump. This happens while driving and in park.

I can give it gas for about 8 seconds while in park and the brake light will go off and I will have pressure (sound) and normal brake again on the first pump but the same as before on the second and third pumps and then the brake light comes back on again.

The thing I cannot figure out is I can be driving down the road doing 60mph running a bout 2k rpm and when I turn on the blinker to change lanes the RPM's will jump 200-400 and when giving it steady gas and tapping the brake pedal it will jump more like 300 to 500 RPMs. Is this the vacuum pump or brake booster. Just replaced front calipers, rotors and pads.

What I cannot figure out is the blinker issue? Why would the RPM's and vacuum change when the blinker is turned on? It will do it when turning on the left blinker and the right. Do you think it is the vacuum pump? I would appreciate any insight on this one. You all have come through for me before! Thanks so much! This is a 95 F250 BTW
 

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Discussion Starter · #13 ·
The hard brake pedal sounds like the vacuum pump to me. It sounds like the pump is on its way out and so it isn't producing a lot of vacuum, and when you rev up, the pump works a little harder and is able to build up enough vacuum needed to operate the brakes for a short period of time.

As for the other stuff... I'm at a loss here. Maybe there is more than one problem and the symptoms are getting mixed up with each other. I say replace the pump and see what kind of issues are left after the repair.

One thing I do know, is that the pump operates more than just the brakes. I don't remember what exactly but it runs vacuum to a distribution block so other systems can use it. Not sure if any of them would cause your particular issues though.
 

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Vacuum pump provides "power" to the power brakes and the HVAC controls, that's it. If Ford had realized in the '90s that the Cold War and the disco era were over, they would've ditched the vacuum HVAC controls for simple mechanical cables, and gone to hydroboost brakes, and there'd be no need for a vacuum pump.

Sounds like your vacuum pump is marginal - works initially but can't keep up with the demand of repeated pedal presses. Test - repeat the procedure, 'til the pedal is hard and the light goes on, then try operating the HVAC controls. If you _don't_ hear the control flaps moving like you usually do, then it's most likely the pump.

RPM issue - automatic transmission, I'll bet? Check your center stop light in the cab roof. Turn signals and brake lights are tied together (use the same bulb filaments on the bulbs in the bed). By some weird eddy current, when you turn on your turn signal, and the center stop light bulb is burned out, that sends some stray signal back to the PCM making it think you've pressed the brake pedal, and it thus unlocks the torque converter. Another of Ford's brilliant designs. If they had separate bulbs behind orange lenses for the turn signals in the bed, like most import cars have, there'd be no tie between the turn signals and brake lights, and this sort of nonsense wouldn't happen either.

So you get a double dose of "Thank you, Ford, may I have another?".....
 

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Well, I ordered a Dorman pump online going to give it a try. I will test it again with the HVAC in mind. Yes auto tranny. You have got to be kidding me on the bulb issue. LOL! Thought for sure all vacuum related. Truly amazing! Thanks going to go check it now.
 

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.....[/QUOTE]RPM issue - automatic transmission, I'll bet? Check your center stop light in the cab roof. Turn signals and brake lights are tied together (use the same bulb filaments on the bulbs in the bed). By some weird eddy current, when you turn on your turn signal, and the center stop light bulb is burned out, that sends some stray signal back to the PCM making it think you've pressed the brake pedal, and it thus unlocks the torque converter. Another of Ford's brilliant designs. If they had separate bulbs behind orange lenses for the turn signals in the bed, like most import cars have, there'd be no tie between the turn signals and brake lights, and this sort of nonsense wouldn't happen either.

So you get a double dose of "Thank you, Ford, may I have another?".....[/QUOTE]

Yep, you got it. No cab brake light. Will have to pick one up. My bulb though is not a 3157 as the ones in the bed this one is one of the push in types like a tag lamp. They all feel really loose though even the white lights that light up when the door is open they are push in types as well all 3 of them. Wonder if I could pick up a whole light assembly at the salvage yard. It was dark outside but it looks like the whole assembly may just plug in up there. Were there different one's for different years since my bulbs are the push in type? Amazing! Thanks! I love this forum!
 

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Vacuum pump provides "power" to the power brakes and the HVAC controls, that's it. If Ford had realized in the '90s that the Cold War and the disco era were over, they would've ditched the vacuum HVAC controls for simple mechanical cables, and gone to hydroboost brakes, and there'd be no need for a vacuum pump.

Sounds like your vacuum pump is marginal - works initially but can't keep up with the demand of repeated pedal presses. Test - repeat the procedure, 'til the pedal is hard and the light goes on, then try operating the HVAC controls. If you _don't_ hear the control flaps moving like you usually do, then it's most likely the pump.

RPM issue - automatic transmission, I'll bet? Check your center stop light in the cab roof. Turn signals and brake lights are tied together (use the same bulb filaments on the bulbs in the bed). By some weird eddy current, when you turn on your turn signal, and the center stop light bulb is burned out, that sends some stray signal back to the PCM making it think you've pressed the brake pedal, and it thus unlocks the torque converter. Another of Ford's brilliant designs. If they had separate bulbs behind orange lenses for the turn signals in the bed, like most import cars have, there'd be no tie between the turn signals and brake lights, and this sort of nonsense wouldn't happen either.

So you get a double dose of "Thank you, Ford, may I have another?".....
Here is what my bulbs look like. Do you think that would still be the issue for my RPM's
 

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Vacuum pump provides "power" to the power brakes and the HVAC controls, that's it. If Ford had realized in the '90s that the Cold War and the disco era were over, they would've ditched the vacuum HVAC controls for simple mechanical cables, and gone to hydroboost brakes, and there'd be no need for a vacuum pump.

Sounds like your vacuum pump is marginal - works initially but can't keep up with the demand of repeated pedal presses. Test - repeat the procedure, 'til the pedal is hard and the light goes on, then try operating the HVAC controls. If you _don't_ hear the control flaps moving like you usually do, then it's most likely the pump.

RPM issue - automatic transmission, I'll bet? Check your center stop light in the cab roof. Turn signals and brake lights are tied together (use the same bulb filaments on the bulbs in the bed). By some weird eddy current, when you turn on your turn signal, and the center stop light bulb is burned out, that sends some stray signal back to the PCM making it think you've pressed the brake pedal, and it thus unlocks the torque converter. Another of Ford's brilliant designs. If they had separate bulbs behind orange lenses for the turn signals in the bed, like most import cars have, there'd be no tie between the turn signals and brake lights, and this sort of nonsense wouldn't happen either.

So you get a double dose of "Thank you, Ford, may I have another?".....
Are there any places that sell OEM replacements that you know of for that light assembly. My bulbs feel really loose in there and I would not mind replacing it. I have seem some used on E-Bay and some LED one's but don't want LED's.
 

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OEM, you'd probably have to go junkyard hopping. Or check Craigslist or the Classified section on this forum and the other truck forums.

Those housings tend to overheat, esp. if you leave the door open or the dome light on for a long time. The white bed illumination lights heat up the whole housing, and sometimes that causes the brake light to fail. One option would be to replace the housing, then put a standard tungsten bulb in for the brake light, and put LED bulbs in for the illumination lights. They'll produce a lot less heat.
 
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