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Pelican Technical Article:

Alternator Replacement

Steve Vernon

Time:

5 hours5 hrs

Tab:

$230 to $900

Talent:

***

Tools:

(2) 17mm, 8mm, 12mm wrenches. 17mm socket, flathead screwdriver, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

Alternator

Hot Tip:

Make sure to reconnect the air duct

Performance Gain:

Proper running accessories

Complementary Modification:

Change the belt

Replacing the alternator on the Porsche 951 is not a difficult job. It is just very time consuming. There are a lot of components that need to be moved out of the way to safely replace the alternator, and there really are not any short cuts you can take. If you are planning on replacing it give yourself at least five hours the first time you do it.

You will be loosening the belts from below so you will need to raise and support the front of the vehicle; please see our article on safely raising and supporting your Porsche for additional assistance. You are also going to be draining the coolant to a certain level, so if you have not flushed your cooling system in over two years, now would be a good time to consider it.

When working with the alternator it is a really good idea to disconnect both the positive (yellow arrow) and negative (red arrow) cables from the battery.
Figure 1

When working with the alternator it is a really good idea to disconnect both the positive (yellow arrow) and negative (red arrow) cables from the battery. At the very least remove the ground or negative cable and place it so that it cannot accidentally come in contact with the battery post while you are working. I personally remove both cables to be safe.

With the vehicle safely raised and supported remove the under engine tray (red arrow, tray removed).
Figure 2

With the vehicle safely raised and supported remove the under engine tray (red arrow, tray removed). There should be eight 10mm bolts, please see our article on under tray removal for additional assistance.

You will need to remove the alternator belt from the pulley to change out the alternator; begin by using a 17mm socket and loosening the pivot bolt on the A/C compressor (red arrow).
Figure 3

You will need to remove the alternator belt from the pulley to change out the alternator; begin by using a 17mm socket and loosening the pivot bolt on the A/C compressor (red arrow).

Use two 17mm wrenches and separate the double nuts on each end of the turnbuckle (red arrow).
Figure 4

Use two 17mm wrenches and separate the double nuts on each end of the turnbuckle (red arrow). With the nuts loose use the 17mm wrench and turn the turnbuckle so that it loosens tension on the belt.

If there is not enough room to remove the belt you can disconnect the turnbuckle from the A/C mount (yellow arrow) and slip the belt off (red arrow).
Figure 5

If there is not enough room to remove the belt you can disconnect the turnbuckle from the A/C mount (yellow arrow) and slip the belt off (red arrow). Check the condition of the belt for fraying, cracks and dry rot and replace as needed. You do not need to remove the power steering belt if you are just replacing the alternator, but if you need to install a new belt you must remove the power steering belt first. Please see our article on accessory belt removal for additional assistance.

There is a cooling tube from the left front of the vehicle to the rear of the alternator (red arrow).
Figure 6

There is a cooling tube from the left front of the vehicle to the rear of the alternator (red arrow). This tube is very important to the function and life of the alternator. Due to its proximity to the turbo the alternator needs to have this source of cooling air. If your turbo is missing this tube or it is damaged you should replace it while performing this work. Use a flathead screwdriver and remove the hose clamp and tube from the air duct on the front (yellow arrow).

There is a plastic air diverter on the rear of the alternator that channels the air to the alternator.
Figure 7

There is a plastic air diverter on the rear of the alternator that channels the air to the alternator. While you can remove the diverter once the alternator is removed, I like to remove the 8mm nuts while the alternator is still mounted. The plastic tends to get brittle over the years and you run less risk of damaging it if you remove the hardware while the alternator is stationary. Reach up from below with an 8mm wrench and remove the nut and washer (red arrow).

You will need to remove the air box, the metering sensor (red arrow) and the intercooler to intake pipe (yellow arrow).
Figure 8

You will need to remove the air box, the metering sensor (red arrow) and the intercooler to intake pipe (yellow arrow). Please see our article on these procedures for further assistance.

Remove the J pipe or air intake to the turbocharger (red arrow).
Figure 9

Remove the J pipe or air intake to the turbocharger (red arrow). Use a turkey baster or fluid pump and drain enough fluid (green arrow) to below the level of the hose to cross over pipe and electrical coolant pump (yellow arrow). Please see our articles on these procedures for additional information.

Disconnect the hose to the electrical coolant pump (yellow arrow).
Figure 10

Disconnect the hose to the electrical coolant pump (yellow arrow). You can see how tight the alternator is in the engine (red arrow).

Remove the cross over pipe from the front of the vehicle (red arrow).
Figure 11

Remove the cross over pipe from the front of the vehicle (red arrow). Please see our article on cross over pipe removal for further assistance.

Use an 8mm wrench and remove the nut and washer on the rear of the air diverter (red arrow).
Figure 12

Use an 8mm wrench and remove the nut and washer on the rear of the air diverter (red arrow).

Use a 17mm socket and remove the two bolts (red arrows) holding the alternator to the mount.
Figure 13

Use a 17mm socket and remove the two bolts (red arrows) holding the alternator to the mount.

With everything removed you can now easily and safely move the alternator out of position and remove the 8mm (yellow arrow) and 12mm (red arrow) nuts from the cables and remove the alternator from the car.
Figure 14

With everything removed you can now easily and safely move the alternator out of position and remove the 8mm (yellow arrow) and 12mm (red arrow) nuts from the cables and remove the alternator from the car. Note: if you have not already disconnected the battery you must disconnect it before performing this step.

With everything out of the way you can easily remove the air diverter and pipe and check for the condition of it.
Figure 15

With everything out of the way you can easily remove the air diverter and pipe and check for the condition of it. Installation is the reverse of removal. Do not forget to install the coolant and bleed the system.

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