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Accessory Drive Belt Replacement

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As reported in previous posts, the other week I discovered some damage to the Accessory Drive Belt of my S Type and, having checked the workshop manual, decided this was was a task I could easily do myself. British Parts did a sterling job in getting the new belt to me in less than 24 hours but I only got around to fitting it last weekend. The description of the process in the manual is exceptionally brief, consisting as it does of only three or four lines; but based on performing the task from underneath the car. Which is all well and good but, unless you have the luxury of a post-lift, this means either getting the car onto a set of suitably high ramps or using the jack and axle stand approach.

When I discovered the damaged belt I had concluded, rightly, that I could in fact do the job from above by simply removing the plastic pipe from between the air-filter and throttle body to provide access to the right hand side of the engine. So, battery negative disconnected, loosen the two large jubilee clips, remove pipe at the throttle body end, tease out the sensor (air flow/temperature? - must find out), rotate the pipe approx a quarter turn toward the front and disconnect from the air filter housing.

Next; check the actual belt run against what the book says - just to make sure it agrees with the diagram and to understand where any obstacles are. Insert 3/8 socket drive into belt tensioner and pull to left, a strong spring so a little muscle or longer wrench handle required, and ease the belt off the top pulley on the left hand side of the engine. Release the tensioner and unthread the old belt from the other pulleys - theres a bracket behind which the belt has to be navigated but it is not necessary to remove this. Check old belt against new to ensure correct length, width and the number and depth of ridges in the new belt - note, the old belt may be a little longer than the new one as it will stretch a little over time. If ok; remove the socket drive from the belt tensioner, the belt run is behind the tensioner body so you will need the wrench out of the way, thread the belt behind the bracket mentioned above before attempting to locate it on the various pulleys. When you have a loop on each side, follow the diagram - by feel because you will not be able see and do at the same time in some instances - thread the belt over the pulleys on the left side of the engine and then the right side but do not try to install it over the tensioner pulley yet. Once you have checked the belt run to ensure that it is following the correct path over all the other pulleys ease the belt off the topmost pulley on the left had side, this gives you sufficient free movement of the belt to get it behind the body of the tensioner and over the tensioner pulley, with this done insert the socket drive, get hold of the belt on the left hand side and apply pressure to the tensioner to give you the slack needed to get the belt back over the topmost pulley on the left. Release the tensioner and check the belt is tight and centred properly on all the pulleys; adjust as needed. When satisfied all is correct re-fit the air supply hose between the air filter and throttle body - not forgetting the sensor.

Re-connect battery and follow the usual procedure to enter radio code, epb, windows and accelerator calibration - but add check for any odd sounds or belt movement after starting the engine.

Blunder Then collect and put away your tools - b%^%%r! - remember to remove the drive socket and wrench from the belt tensioner before re-installing the air supply pipe. Fortunately I had used the ratchet wrench and the handle had come to rest against the inner wing and was held firmly there by the pressure from the belt tensioner - otherwise I would really have thrown a wrench into the engine. Must, must, must remember - spanner check before I start the engine.:oops::blushing:

Mystery Solved Some weeks ago I had heard what I thought was a twig or similar caught somewhere in the nearside front wheel arch - made a sound similar to cards we used to put into bike wheels - and the frequency increased/decreased in line with speed. Investigations at the time revealed nothing and after the noise disappeared I thought no more of it. However, while I was examining the belt run through the various pulleys I found a couple of spots where bits of the old belt had obviously been thrashing. So if your car sometime make a sound like a card against a bike spoke - check the drive belt.🤔

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I done my belt from the top, same method as you but I never touched the battery, I tried that many belts to find one to fit that I can do a belt change in 5 minutes.

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Hi David,

A bit belt and braces I know but theres always that nagging doubt about accidentally spinning the alternator pulley too fast and frying something. Took me 45 minutes or thereabouts, including retrieving my socket wrench, but I agree it can easily be done in 5-10 if you're sure of the method and belt run. Hopefully neither of us will need to do it again any time soon.

Cheers,

Steve

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