X350 V8 Serpentine belt change at 86,200 miles.

[J44EAG]

At long last, a warm February day with plenty of sun. Always encouraging.

I`ll add images to this thread once I`ve resized them to suit the idiosyncrasies of this site! (Now done) We really do need to get this issue fixed. Photography below engine level in a small space is not easy and getting any real value from the images I took when doing this job have very limited value. Sorry then. No images of the front of the engine.

My 4.2R needed a serpentine belt change. I suspected the original factory fitted belt was still in place after something like twelve years on the road with 86k miles covered.

The procedure entails a fair amount of stripping out of surrounding components to get at the two belts. In front of it, the R also has the super charger belt which has to be removed to gain access. Naturally aspirated V8 models do not have this extra belt, so the job is just a little easier.

I began by removing the air inlet pipe from the air flow meter tube to the intake plenum. Two large jubilee clips are removed to allow the pipe to be taken from the car. Remove the part load breather pipe from the induction pipe. The entire air cleaner box should be removed for ease of access which is held in place by just one long 8mm bolt. Two screws hold the air snorkel to the front slam panel. The snorkel is easily removed from the air box to facilitate easier removal.

Removing the header tank cap allowed me to pump out the tank and save the coolant for re-use. Remove the long bolt securing the tank to the slam panel. Slide the tank to the right disengaging the tank lugs on the left side from the body mount. Lift the tank and remove the low level warning sensor plug from its socket on the sensor. Locate the spring clip holding a hose to the lower portion of the tank. USE LONG NOSE PLIERS TO PULL THE CLIP TO THE RIGHT.

Get your hand on the clip and fully extract. Guard this clip with your life and do not drop or loose! A lost clip might mean having to buy a complete new tank. Pull out the hose from the header tank. Expect to drop some coolant when separating the hose from the tank. Remove the two small hoses at the top of the tank. Go easy with this operation. The stub pipes on these tanks embrittle with age and heat. They snap off easily.

If that happens, a new tank is the only option. Supercharged and non supercharged models use different tanks. If needing a new tank, ensure you get the right one. The supercharged tank is more expensive as it has an extra chamber built in for the supercharger coolant circuit.The replacement tank is about £100. Use only the OE product, not a Chinese copy. Remove the tank from the car.

Now disconnect the pipe from the from of the thermostat housing and move out of the way. You will now see the belt runs around their pulleys. Photograph or draw a diagram of the belt runs. The front belt drives just the supercharger. The layout is straight forward. Use the square half inch drive peg on a torque wrench and lever the tensioner clockwise as you look at it. Slip off the charger belt. You may leave it dropped down over the tensioner unit. Going now to the primary drive belt, use a 3/8 adaptor on the drive peg of the torque wrench. Lever the tensioner anti-clockwise to relieve belt tension whilst slipping the belt off at the water pump. Removal of the supercharger belt idler pulley from its bracket helps greatly now. Space is tight and getting the serpentine belt off the alternator, PAS pump and aircon pump and idler pulleys can be a bit frustrating. It is rather fiddly work which is perhaps made easier if you have done this job previously!

Place the new belt in a sink full of hot water for ten minutes before fitting. This will make the belt much softer and easier to handle and fit. Fitting is the reverse of removal and is easier said than done. Ensure you have the belt sitting centrally on all idlers and in grooved pulleys. Check, check and check again before refitting the charger idler pulley and then the charger belt. Refit the displaced components and refill with coolant. Carefully start the engine and once again check belts are running on pulleys and idlers correctly. Warm the engine and watch for the thermostat to open. Squeeze hoses to expel trapped air and open the bleed on the header tank to purge air from the supercharger intercooler circuit. Establish the correct coolant level, replace the tank cap and take the car for a short run. Check the coolant level again and adjust if required. Job done.

Cracks and splits across my old serpentine belt were found at 86k miles. I believe the belt could be the one that the car came fitted with from the factory. I`d say there was about a further 5k miles of safe use left on that old belt but I`d rather not have driven the car to find out! A wrecked engine due to an overheat caused by a broken belt is rather more expensive than the cost of a new belt and fitting. The time taken was about two hours and I`d describe the degree of difficulty as moderate for a reasonably competent and experienced fitter.

I`m glad this job is now done. I`d begun to worry about that belt and I`m glad to see it gone. It makes a reasonable spare to carry in the spare wheel well.
The prime belt is quite a length as seen in this image. Fitting it can be quite a challenge.

I`ve used Dayco belts for many years now without issue.

The cost for this serpentine belt was £20.50 delivered via ebay. A Jaguar OE belt I saw was listed at about £95! Make your own choice. The supercharger belt I fitted sixteen months ago is also a Dayco product and came for a similar price.

Perhaps make a note of the Dayco part numbers for future use.

Dayco after-market 6PK-2310 is the main drive belt for water pump, alternator, PAS and air con.

Dayco after-market 8DPK-1355 is the later supercharger belt cross referenced to the OE part of C2C37055. Note this is a double V ripped belt (Both sides of the belt are ribbed) fitted for use on SC cars from around MY55 onwards. Some early cars may have had their SC idler pulleys and belt tensioner unit changed to the later type due to belt flinging or slipping antics. You can tell which units are fitted to your SC belt system by looking to see a double ribbed belt and a shouldered and ribbed idler pulley below the super charger drive pulley. That denotes the car has the updated and uprated drive train in place. Cars that are not fitted with this mod kit have a smooth backed drive belt and a plain smooth pulley with rounded shoulders. Early and late tensioners look identical but the tension spring is stronger in the later uprate kit.



Mike K

[oldtimer]

Well done Mike, not the sort of job to do on the side of the road on a dark wet night.
Not familiar with this installation, is it possible to carry out a visual examination of the belt while installed?
What made you decide to do yours and what was the state of the removed item

[J44EAG]

You need to get the belt off and bend back on itself to see the true condition. This is as described at the bottom of my post.

I suspected that as the car had little to show other than just oil services over the years and only minimal invoices for replacement parts, that most wearable parts would certainly be past their best. Remember the air filter I took out? Diabolical. That lead me to systematically rip the car apart and check or zero time everything that could possibly cause an issue. This vital belt was one that I intended doing last year but never got around to it.

Only when you have a machine in pieces can you see what it is like. Often what you find is completely unacceptable, so it just gets replaced. Twelve years service is more than enough for any drive belt. I need to see what the recommended replacement mileage is for this belt on the service schedule.

Next under the hammer is the air compressor and an overhaul. In a few years time, my prolapsed discs and trapped sciatic nerve will totally prevent me from fixing my own car. I must get this car to as good as is possible whilst I can still walk and crawl. That`s why I`ve dug in so deep on this car. For me, its a keeper and one that I understand and know where it stands mechanically. For me it just has to be done rather quicker than I`d like to have to do it. Time is running out.....

Mike