820 cambelt change

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richard moss
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Location: Wolverhampton

820 cambelt change

Post by richard moss » Thu Sep 24, 2009 1:16 pm

Please note: do not attempt this task without the aid of a workshop manual for checking torque wrench settings. I tend to do bolts by feel.

Jack car up on driver's side, support on an axle stand, remove OSF wheel and remove the auxilliary belt cover (3 x 10mm bolts).

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Rotate the engine whilst pushing an 8mm drill bit into the hole in the engine end plate until the drill bit engages in the locking slot on the flywheel. I get my "helper" to push the drill bit whilst I turn the engine.

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Use a 15mm spanner to pull the auxilliary belt tensioner rearwards and slip off the belt.

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Undo the 4 x 8mm bolts on the crank pulley followed by the main 19mm pulley bolt (easy if you use a 12v impact wrench). The pattern for the 4 bolts is not symmetrical - this ensures that you get the orientation right when refitting.

EDIT: In hindsight, I would suggest that these bolts are loosened, but not removed, with the car down on its wheels - if the locking pin is used to hold the engine whilst loosening the crank pulley bolts there is a slight chance that the pin may bend or break.

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Support the sump with a trolley jack and block of wood before removing the cambelt end engine mount. Access to the engine mount and cam cover is easier if you remove the 8mm bolt that clamps the aircon pipe to the wing (the pipe can be eased out of the way as needed).

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I removed the top cam cover (8mm bolts) before removing the engine mount, but you can do it either way.

There are three pieces to the cover - I remove them in the order top, middle, bottom. Some of them are hard to get to and a selection of 8mm spanners and 1/4" drive sockets will help - I loosen them with the right angled tube spanner shown earlier then spin them off with a 1/4" drive socket. The engine will need to be jacked up to get to some of them.

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Once the covers are off, you will be able to see the timing marks on the cam sprockets - note the position. The camshafts shouldn't move far, if at all, when the belt is removed.

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I forgot to show the tensioner but it's released by loosening the 10mm bolt in its centre, the tensioner pulled rearwards and the centre bolt tightened to hold it out of the way. The timing belt can then be slipped off the sprockets.

I fit the new belt by locating it over the bottom pulley and in front of the tensioner before slipping it over the front cam pulley then the rear. The length of belt between the bottom pulley and the front cam pulley (and between the cam pulleys) needs to be kept tight as the slack in the belt is taken up at the rear by the tensioner.

The manual then says to use a torque wrench (40 lbft) to turn the inlet cam sprocket rearwards to tighten the front of the timing belt before releasing the tensioner bolt, letting the tensioner spring forward and re-tighten the tensioner bolt. If you arms are 8 feet long you can do that on your own, but working on my own, I just tighten the belt by pushing forward on the tensioner until it feels right! Not had one fail yet!

After releasing the tensioner and removing the flywheel locking pin (drill bit!), turn the engine over by hand a couple of times to check that there are no nasty noises from inside and the timing marks still line up after rotating.

The rest is "refitting is the reverse of removal" as the Haynes manual says - refit the plastic timing covers, crank pulley and aux drive belt. Remove the coil HT lead or multiplug from the coil pack (depending upon ignition type) and spin it over a couple of times on the starter. Then, fingers crossed, reconnect the ignition leads and fire it up!

It was noticeable that the old belt was very much more loose than the new one - it was almost 5 years old and about on 60k miles (the specified change interval).

Feel free to comment/ask questions.
1990 827 Sterling manual
1990 Jaguar Sovereign 4 Litre on LPG
1969 MGC GT (currently hibernating)

GOY189
Posts: 473
Joined: Sun Oct 19, 2008 5:08 pm

Re: 820 cambelt change

Post by GOY189 » Tue Oct 06, 2009 4:18 pm

Thanks for that Richard, Its a job that I've usually chickened out of when a timing belt needed replacing. Costs a lot at a garage. You don't appear to use any of these locking devices to lock the camshafts. My big fear would be movement of 1 camshaft during the belt change.

regards

Mike Maher

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richard moss
Posts: 233
Joined: Wed Sep 24, 2008 5:23 pm
Location: Wolverhampton

Re: 820 cambelt change

Post by richard moss » Tue Oct 06, 2009 9:15 pm

Mike,

You don't really need a camshaft locking tool on T and M series engines because the most they are likely to move is a couple of degrees and the timing marks are easy to re-align as you put the belt back on. The crank is locked by the pin.

I think it took less than 2 hours to do.
1990 827 Sterling manual
1990 Jaguar Sovereign 4 Litre on LPG
1969 MGC GT (currently hibernating)

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Freewheel
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Joined: Wed Sep 24, 2008 10:45 pm

Re: 820 cambelt change

Post by Freewheel » Sun Oct 11, 2009 10:53 pm

Another great post from the redoubtable Mr Moss...
Paul H. - '49 'Speed' 75; '55 90
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richard moss
Posts: 233
Joined: Wed Sep 24, 2008 5:23 pm
Location: Wolverhampton

Re: 820 cambelt change

Post by richard moss » Tue Oct 13, 2009 12:01 am

Freewheel wrote:Another great post from the redoubtable Mr Moss...
Thank you kindly, good sir.
1990 827 Sterling manual
1990 Jaguar Sovereign 4 Litre on LPG
1969 MGC GT (currently hibernating)

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