I replaced the alternator clutch pulley on my 2000 V40 last week-end. Here are a few notes on the job that apply to the B4204T2 engine.

What's an alternator clutch pulley? It's a pulley that free wheels in one direction, allowing the alternator rotor to overrun the serpentine belt between crankshaft power pulses and when the engine revs are falling.

Why replace it? The alternator rotor has a lot of angular momentum. Without a clutch pulley this angular momentum is constantly exerting forces on the serpentine belt, increasing the wear on the belt and other components in the serpentine belt path and also reducing your gas mileage. If the clutch pulley is seized the pulley may unscrew from the alternator shaft and fall off or even shear off the alternator shaft destroying the alternator. Worst case, the serpentine belt will break and derail your timing belt, trashing your cylinder head.

How do you know if the clutch pulley's bad? Take a look at the serpentine belt tensioner with the engine running and A/C off. If the tensioner pulley is jumping around, the alternator clutch pulley needs to be replaced. (A small amount of motion in the tensioner pulley is normal). You can also watch your alternator rotor when someone else shuts off the engine. If the clutch pulley is working correctly you'll see the alternator rotor continue to spin for a couple of seconds after the engine stops. If the clutch pulley is seized the alternator rotor will stop dead with the engine.

To do the job you need the correct spline tool for the alternator clutch pulley and an air impact wrench. The cheapest place to get the spline tool is Amazon. You'll also need your radio code.

First, disconnect the battery negative terminal and position it so it can't accidentally touch the negative battery post.

Next, remove the serpentine belt from the power steering pump pulley using a long 14mm box wrench on the serpentine belt tensioner. The serpentine belt can stay in the engine bay.

To get to the alternator you need to move the power steering pump. The power steering pump can be moved out of the way without detaching the hose from the power steering reservoir or the hard line to the steering rack. There are four bolts that are accessed through holes in the power steering pump pulley. You need to remove the three bolts at the top left and at the bottom left and right. The top right bolt attaches the belt shield to the power steering pump and can be left alone. There is a wiring connector and a second wire clipped to the belt shield. Gently lever these off the belt shield with a screwdriver. You will also need to remove the brace that runs from the inlet manifold to the power steering pump. With these three bolts and the brace removed the power steering pump can be picked up and moved to the rear left of the engine bay.



Next, disconnect the two wires from the back of the alternator. One has a plastic shield over a screw terminal, the other is a faston type terminal.

Now unscrew the two long bolts that secure the bottom of the alternator to the accessory bracket. These two bolts are also the top two (of four) bolts that secure the A/C compressor. The left-hand bolt also secures the bottom of another metal brace. You won't be able to remove either of these bolts completely but they need to be pulled far enough out to release the alternator.

Now remove the one remaining bolt on the pulley side of the alternator that holds the alternator to the accessory bracket. Finally, from under the car, loosen the two bottom bolts securing the A/C compressor.



The alternator is now free and can be pulled up and to the left. You do not need to completely remove the alternator from the engine bay. Rotate the alternator so the clutch pulley is facing upwards. Now use the spline tool, a 17mm socket and your impact wrench to remove the clutch pulley from the alternator shaft. The clutch pulley has a left hand thread so you will be spinning the impact wrench clockwise to remove the pulley. It's not necessary to counterhold the alternator shaft as the inertia of the alternator rotor working against the impulses from the air impact wrench is sufficient to loosen the pulley. You may want to use some Kroil or a similar penetrant to help the pulley release from the alternator shaft.

Install the new clutch pulley the same way, this time spinning the impact wrench counter-clockwise to tighten the pulley on the alternator shaft.

Reassemble all in reverse order. Do not over-torque the threaded wire connection on the back of the alternator. Check the plastic pulley on the serpentine belt tensioner for any looseness or roughness. This pulley is a weak spot in the serpentine belt path and it should be replaced if the bearing is not smooth and tight.

Reconnect your battery, punch in your radio code and enjoy your quiet serpentine belt and stationary belt tensioner.

 

Learn something new everyday. Thank you. Where did you buy the new alternator clutch pulley?

 

Volvo sells them. I got mine from tascaparts.com. The alternator clutch pulley is one of the most overlooked maintenance items, imo. They rarely last longer than 100,000 miles.

Most Volvos have alternator clutch pulleys, btw, but some do have solid alternator pulleys from the factory.

 

Your timing is perfect for me. My 2001 sometimes makes a rattling sound with the belt tensioner jumping around quite alot. I replaced the belt tensioner which helped but I'm still getting more movement than I remember. Your write-up could very well explain why.

 

There's an easier way to replace the alternator clutch pulley if you have the correct counterhold tool. The alternator shaft has a 10mm external hex. If you have the Volvo (or equal) counterhold tool to hold the alternator shaft stationary you can move the ABS unit out of the way and then change the pulley without touching the alternator or power steering pump.