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.
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
Tools needed 3
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
• 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.
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.
Vehicle won’t start:
Ensure batteries are connected.
Vehicle will not pull out:
Ensure the parking brake is disengaged.
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.
Last edited by klm89gh34; 01-12-2011 at 07:01 PM.