Porsche 924S & 944 Cambelt and Balance Belt how to / Replacement Guide

Porsche 924S & 944 Cambelt and Balance Belt Replacement Guide

Introduction

Changing the cambelt and balance belt on a Porsche 924S or 944 is one of those jobs that many owners approach with a mixture of excitement and dread. The front of the engine can look intimidating when the covers come off, but if you take your time, stay organised and double-check your timing marks, it is actually a very straightforward job.

This guide covers the basic cambelt and balance belt replacement procedure on the Porsche 924S and 944 range. While there are some variations between engines, the principles remain largely the same.

If you're already this deep into the front of the engine, it also makes sense to inspect or replace components such as the water pump, tension rollers and front oil seals while everything is easily accessible.

Tools Required

24mm socket and ratchet
19mm socket and spanner
17mm spanners and sockets
13mm spanners and sockets
10mm socket
4mm Allen key
Flywheel locking tool
Porsche belt tensioner wrench
Two-prong tensioner adjustment tool
Tippex or paint marker
Torque wrench
Drain tray
Belt kit - https://stuttgartspares.co.uk/products/porsche-924s-944-944-turbo-timing-belt-kit-1x-partworks-94410524105?utm_source=copyToPasteBoard&utm_medium=product-links&utm_content=web
Tools - https://stuttgartspares.co.uk/products/porsche-924s-944-engine-service-tool-set-fortiming-belt-change-special-tools-00072192000
water pump - https://stuttgartspares.co.uk/products/porsche-924s-944-944s-water-pump-1x-geba-95110602110

Step 1 – Raise the Vehicle Safely

Ideally this job is carried out on a vehicle lift or raised ramps. Having easy access underneath the car makes life much easier, particularly when removing the starter motor and installing the flywheel locking tool.

Disconnect the battery before beginning any work.

Step 2 – Remove the Starter Motor

Remove the starter motor using the two 19mm mounting bolts.

Once removed, locate the flywheel inspection bung near the distributor area and remove it.

Using a 24mm socket on the crankshaft pulley bolt, slowly rotate the engine until Top Dead Centre (TDC) is reached.

You can see the TDC mark through inspection hole next the distributor cap.

At this point:

The flywheel TDC mark should be visible.
The white timing mark on the camshaft pulley should align with the pointer on the rear belt cover.

This is your starting point and should be checked repeatedly throughout the job.

Step 3 – Install the Flywheel Locking Tool

With the engine at TDC, install the flywheel locking tool through the starter motor aperture.

This is one of the most useful tools you can own for a 944.

The locking tool serves two important purposes:

Prevents the crankshaft moving during belt replacement.
Allows the lower crankshaft pulley bolt to be loosened and tightened safely.

With the flywheel locked, the crankshaft timing position is secured for the remainder of the job.

flywheel locking tool here. https://stuttgartspares.co.uk/products/porsche-924-944-968-crankshaft-locking-tool-1x-partworks-00072192060

Step 4 – Remove the Radiator Fan

The radiator fan is secured using four 10mm fixings.

Removing the fan at this stage creates significantly more working room at the front of the engine and makes the rest of the job far easier.

Step 5 – Remove Auxiliary Drive Belts

The power steering belt sits on the left-hand side of the engine when viewed from the front of the vehicle.

The adjustment bar uses 13mm fixings and incorporates both left-hand and right-hand threads. Shortening the adjuster bar releases tension and allows the belt to be removed.

The alternator belt uses a similar arrangement but with 17mm fixings.

Remove both belts before continuing.

Step 6 – Remove Belt Covers

Porsche 924S 944 cam belt

Remove the distributor cap and rotor arm.

The rotor arm

is retained using a 4mm Allen screw.

Next remove all timing cover fixings and carefully remove the covers.

For the first time you'll be able to see the complete belt arrangement.

At first glance it looks complicated, but don't panic. Take photographs as you go and work methodically.

Step 7 – Remove the Balance Belt

Belt service tool kit - https://stuttgartspares.co.uk/products/porsche-924s-944-engine-service-tool-set-fortiming-belt-change-special-tools-00072192000

Remove the lower crankshaft pulley.

Locate the balance belt tensioner in the lower left corner of the engine.

Using a 17mm spanner and timing belt adjustment wrench, release tension from the balance belt.

Before removing the belt:

Mark the positions of both balance shaft pulleys.

The upper balance shaft pulley should have the V-mark positioned at approximately 12 o'clock.

The lower balance shaft pulley should point roughly towards the 7 o'clock position.

This is an excellent time to add your own Tippex marks for additional peace of mind.

Remove the balance belt.

Step 8 – Remove Balance Belt Rollers

Remove the balance shaft tensioners and guide rollers one at a time.

If this is your first time performing the job, take photographs before removal.

Several rollers appear similar but are installed in specific locations.

Good photos can save a lot of head scratching during reassembly.

Step 9 – Remove the Cambelt

Double-check that the camshaft timing mark remains correctly aligned.

Add your own paint marks if desired.

The cambelt tensioner must now be released.

Loosen the two 13mm mounting bolts but do not remove them.

Using the two-prong adjustment tool, rotate the tensioner to the right to remove tension from the belt.

Retighten the two 13mm bolts temporarily to hold the tensioner in the released position.

The cambelt can now be removed.

Step 10 – Remove Cambelt Rollers

Remove the tensioner assembly from the engine block.

Three 13mm bolts secure the assembly.

Pay particular attention to the orientation of the toothed roller mounted on the tensioner assembly.

It is surprisingly easy to install this roller backwards during reassembly.

Also remove the guide roller mounted near the water pump.

Step 11 – Consider Replacing the Water Pump

At this stage you are approximately halfway through the job.

You can clearly see the water pump and you've already completed most of the labour required to reach it.

This is why many experienced Porsche owners replace the water pump during a cambelt service.

To replace the pump:

Drain the cooling system.
Remove the rear belt cover.
Disconnect water pump hoses.
Remove the mounting bolts.
Clean all gasket surfaces thoroughly.
Install the new pump.

Important Warning

Not all Porsche 944 water pumps are identical.

2.5-litre engines use a smaller impeller design.

Always verify the correct water pump for your specific engine before installation.

Step 12 – Install the New Cambelt

Fit the new cambelt over the crankshaft pulley and camshaft pulley.

Try to maintain tension along the upper run of the belt.

Refit the tensioner assembly.

This can sometimes be fiddly and may require temporarily removing the belt from the camshaft pulley before reinstalling everything together.

Once installed:

Verify timing marks.
Release the tensioner locking bolts.
Apply tension using the two-prong tool.
Tighten the tensioner bolts.

Stop Here and Check Timing

Before moving any further, confirm all timing marks remain correctly aligned.

Never assume.

Always check.

Step 13 – Install Balance Belt and Rollers

Refit all balance belt rollers and guide wheels.

Install the balance belt.

Check that both balance shaft timing marks remain correctly positioned.

While incorrect balance shaft timing will not normally cause engine damage, it can cause noticeable vibration and spoil the smoothness that makes the 944 such a pleasant car to drive.

Apply tension using the balance shaft tensioner.

A useful rule of thumb is that the belt should comfortably twist through approximately 90 degrees.

Too tight and the belt may whine.

Too loose and it may contact the belt covers.

Step 14 – Final Checks

Before reassembly:

Check all 17mm fasteners.
Check all 13mm tensioner fixings.
Check timing marks.
Check balance shaft alignment.

Remove the flywheel locking tool.

Using a 24mm socket on the crankshaft bolt, slowly rotate the engine by hand through at least one complete revolution.

Watch carefully for any tight spots or interference.

If everything rotates smoothly, return the engine to TDC and reinstall the flywheel locking tool.

Recheck timing marks and belt tension.

Step 15 – Reassembly

Reinstall:

Timing covers
Distributor rotor arm
Distributor cap
Alternator belt
Power steering belt
Radiator fan
Starter motor

Finally tighten the crankshaft pulley bolt correctly.

This bolt must be very tight and should always be torqued according to Porsche specifications.

Reconnect the battery.

Congratulations

You've just completed one of the most important maintenance jobs on a Porsche 924S or 944.

Take your time, double-check your work and don't rush the final inspection.

A properly installed cambelt and balance belt will provide years of reliable service and help keep your transaxle Porsche running exactly as Stuttgart intended.

If you're carrying out this job yourself, it's also worth inspecting related service items such as rollers, tensioners, water pumps and seals while everything is accessible.

Happy spannering.

Frequently Asked Questions

How often should a Porsche 944 cambelt be changed?

Porsche originally recommended replacement intervals based on mileage and time. Most specialists now recommend inspecting belts regularly and replacing them every 4-5 years regardless of mileage.

Can a broken cambelt damage a Porsche 944 engine?

Yes. The Porsche 944 engine is an interference engine and valve damage can occur if the cambelt fails. Big time!

What happens if the balance shaft timing is incorrect?

The engine will usually still run, but increased vibration and roughness can occur.

Should I replace the water pump when changing the cambelt?

In most cases, yes. The majority of the labour required to access the water pump has already been completed during the cambelt service.

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