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Balance Shaft Belt Replacement
 
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Pelican Technical Article:

Balance Shaft Belt Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$40 to $110

Talent:

***

Tools:

17mm, 10mm socket, 24mm, adjustable wrench, flywheel lock, flathead screwdriver, 45-degree needle nose pliers, Porsche special tool 9201

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

New belt

Hot Tip:

Make sure engine is at Top Dead Center

Performance Gain:

Proper engine operation

Complementary Modification:

Replace timing belt

Replacing the balance shaft belt is an important part of your maintenance on your Porsche 944. Even if you do not need to replace the belt, it will need to come off to perform work like changing the water pump or timing belt. If you are removing the belt and going to reinstall it, make sure to mark the direction of rotation. In addition, do not turn it inside out.

You are going to need to safely raise and support the vehicle and remove the under engine tray. Please see our article on safely raising and supporting your Porsche 944 as well as removing the under engine tray.

Begin by removing the air box and turbo pipes around the box (red arrow).
Figure 1

Begin by removing the air box and turbo pipes around the box (red arrow). Please see our article on air box removal.

Make sure the engine is set at Top Dead Center (red arrow) and lock the flywheel.
Figure 2

Make sure the engine is set at Top Dead Center (red arrow) and lock the flywheel. Please see our articles on setting your engine at TDC and locking your flywheel.

You will need to remove the distributor cap; please see our article on spark plug wire and distributor cap replacement.
Figure 3

You will need to remove the distributor cap; please see our article on spark plug wire and distributor cap replacement.

With your 944 safely up and supported, remove the under engine trays (red arrow).
Figure 4

With your 944 safely up and supported, remove the under engine trays (red arrow). Please see our article on under engine tray removal for additional assistance.

Next, remove the belts for the power steering pump (red arrow) and the A/C compressor and alternator (yellow arrow).
Figure 5

Next, remove the belts for the power steering pump (red arrow) and the A/C compressor and alternator (yellow arrow). Please see our article on accessory belt replacement.

Use a 10mm socket and remove the bolts holding the upper front engine cover on (red arrow).
Figure 6

Use a 10mm socket and remove the bolts holding the upper front engine cover on (red arrow). Note: I have removed a bunch of things from the front of the motor to get better pictures, but you only need to remove what is listed.

Continue with the 10mm socket and remove the bolts holding the lower cover in place (red arrow).
Figure 7

Continue with the 10mm socket and remove the bolts holding the lower cover in place (red arrow).

Remove the three 10mm bolts holding the distributor cover plate in place (red arrows).
Figure 8

Remove the three 10mm bolts holding the distributor cover plate in place (red arrows).

With the cover removed, take time to make sure that the engine is at TDC and that everything is lining up correctly.
Figure 9

With the cover removed, take time to make sure that the engine is at TDC and that everything is lining up correctly. The mark on the camshaft pulley (red arrow) should line up with the notch in the housing (yellow arrow).

With the engine at TDC, the upper balance shaft pulley should line up with the notch in the rear plastic cover (red arrow).
Figure 10

With the engine at TDC, the upper balance shaft pulley should line up with the notch in the rear plastic cover (red arrow). Someone had marked the front plate on the pulley to assist with the ease of checking alignment (which is a good idea) but you really want to check for the small notch in the rear of the pulley (yellow arrow).

The lower balance shaft has a notch cut in the rear of the pulley (yellow arrow) that lines up with a tab in the rear plastic cover (red arrow).
Figure 11

The lower balance shaft has a notch cut in the rear of the pulley (yellow arrow) that lines up with a tab in the rear plastic cover (red arrow).

After you are insured that everything is lined up while the engine is at TDC and the flywheel is locked, use a 24mm socket and remove the crankshaft pulley bolt (red arrow).
Figure 12

After you are insured that everything is lined up while the engine is at TDC and the flywheel is locked, use a 24mm socket and remove the crankshaft pulley bolt (red arrow).

Next, use a 10mm socket and remove the four bolts holding the pulley to the crank gear.
Figure 13

Next, use a 10mm socket and remove the four bolts holding the pulley to the crank gear. Then remove the pulley (red arrow).

This photo illustrates the main crank pulley (red arrow), the lower balance shaft pulley (green arrow) and the upper balance shaft pulley (yellow arrow).
Figure 14

This photo illustrates the main crank pulley (red arrow), the lower balance shaft pulley (green arrow) and the upper balance shaft pulley (yellow arrow).

Working from below, you are going to loosen the tensioner (red arrow) and the idler pulley (yellow arrow); the balance shaft pulley is between them (green arrow).
Figure 15

Working from below, you are going to loosen the tensioner (red arrow) and the idler pulley (yellow arrow); the balance shaft pulley is between them (green arrow).

Porsche makes a special tool for holding the tensioner in place (red arrow), while releasing the 17mm nut (yellow arrow).
Figure 16

Porsche makes a special tool for holding the tensioner in place (red arrow), while releasing the 17mm nut (yellow arrow). If you do not have the special tool, you can use an adjustable wrench to hold the tensioner in place while loosening the nut. Failure to hold the tensioner in place while loosening the nut can cause damage in the tensioner and lead to its failure. You will also need this to re-tension the belt and hold the tensioner in place while you tighten the nut, when performing the installation.

Use an adjustable wrench or 24mm wrench to hold the tensioner in place, while using a 17mm socket to remove the nut.
Figure 17

Use an adjustable wrench or 24mm wrench to hold the tensioner in place, while using a 17mm socket to remove the nut. You can now remove the belt and replace it. Installation is the reverse of removal. Please skip to steps 20-21 for installation and tightening procedures. If you are going to be replacing the timing belt, you will need to remove the balance shaft pulleys to remove the plastic cover behind them. With all of the tension off you can remove the tensioner (red arrow).

Porsche also makes an expensive tool for holding the balance shaft pulleys in place while removing or installing them, but you can use a large set of 45-degree pliers.
Figure 18

Porsche also makes an expensive tool for holding the balance shaft pulleys in place while removing or installing them, but you can use a large set of 45-degree pliers. Insert the pliers (red arrow) into the two openings in the pulley and hold the pulley in place. While holding the pulley use a 17mm socket and remove the nut (yellow arrow).

When reinstalling the balance shaft pulleys, insert the cut out on the pulley with the O (red arrow) on the keyway (yellow arrow).
Figure 19

When reinstalling the balance shaft pulleys, insert the cut out on the pulley with the "O" (red arrow) on the keyway (yellow arrow). The other cut out in the pulley is for the tab on the metal plate on the front of the pulley to sit in (green arrows).

Porsche makes a special, very expensive tool for measuring the tightness of the belt.
Figure 20

Porsche makes a special, very expensive tool for measuring the tightness of the belt. Thankfully, you can do it by hand. Make sure that the balance shaft pulleys are lined up correctly with the marks and notches listed earlier (yellow arrow). Tension the belt with the tensioner until you can turn the belt where it crosses the timing belt to 90 degrees with your thumb and forefinger (red arrow).

This photo illustrates that the lower balance shaft pulley is lined up correctly (green arrow).
Figure 21

This photo illustrates that the lower balance shaft pulley is lined up correctly (green arrow). Now you need to set the idler. With the belt tightened there should be 1mm of clearance between the bottom of the idler (red arrow) and the belt (yellow arrow). The clearance between the belt and the idler on the top should be about the thickness of a sheet of paper.

While a lot of home mechanics do not have the use of the Porsche $600 special tool 9201, it is a really good idea to check the tension of the belt with this tool.
Figure 22

While a lot of home mechanics do not have the use of the Porsche $600 special tool 9201, it is a really good idea to check the tension of the belt with this tool. There are two different types of belts used: the old style is 15mm wide and the newer style is 18mm wide. Loosen the locknut on the balance belt idler roller and move it away from the balance belt. It should not come in contact with the belt while checking the tension or during tension adjustment. Check the belt tension using special tool 9201. Pull the lock pin on the tool to release the tension roller. Align the drag needle with the gauge needle. Install the tool on the section of the balance belt between the lower and upper balance shaft sprockets. The deflection on the old style belt should be 2.7 +/- 0.3 and the newer style belt 3.5+/- 0.5. Remember to apply counter torque when tightening the tensioner. Installation is the reverse of removal.

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