Topic
Timing 12 years 9 months ago #26020
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Topic Author
- David Aiketgate
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- David
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- mgf mk2 freestyle mpi 16" wheels, in Anthracite.
- Posts: 20139
- Thanks: 4388
Timing Marks etc.
Timing Position.
Crank Pulley in Timing (Safe) Position.
Timing Dots on Crank Sprocket.
Inlet Cam Pulley.
Exhaust Cam Pulley.
Pulleys with Locking Tool in Position.
VVC Rear Cam Pulleys. (This position is used for setting timing. Before cam carrier removal, the pulleys should be positioned with marks facing outwards)
Tips on cam timing
Before removing the belt, make sure that the engine is set to its safe timing marks. In this position, the crankshaft is at 90 degrees before TDC and all the pistons are half way down their bores. This means that the cams can be turned without damaging the valves. The cam pulley marks can be seen after removing upper belt cover.
Only turn the engine over using the crank pulley bolt or by rocking the car with it in gear. Do not turn it using the cam pulley bolts. Removing the spark plugs make this easier.
To undo the crank pulley bolt, do it before removing the belt and make sure that the cam locking tool is NOT in position between the pulleys or you could damage the belt or even bend the valves.
Never turn the crank with the head removed unless the liners are first clamped in position, as they can move. If the timing position has been disturbed, an alternative would be to refit the head with no cams installed so that the valves are closed.
The cam timing tool is only required to assist in final fitting of the cam belt. It is not required at any other time - if the cams move, this is not a problem with the crank in its Safe (Timing) position and they can easily be turned back when required.
Do not use the cam timing tool between the pulleys to hold them while undoing the bolts. The tool to use is either one that picks up on the pulley spokes or you can use some types of oil filter strap wrench (not the chain type) wrapped around the cam pulley.
Cam belts can fail internally and still look new on the outside. If a belt has been contaminated with any fluid (including water!) or pinched it should be replaced.
Final belt tension should only be set after rotating the engine a couple of turns by hand, stopping at the timing position.
Cam timing notch is on the front flange of the crank pulley as shown and positions the crank at 90 Degrees BTDC (Safe or Timing position).
The best crank timing mark is to line the mark between the two dots on the crank sprocket. The crank pulley has been known to slip round on the hub giving a false indication, as the pulley locating key is very small and it is possible to damage it when refitting, again resulting in an incorrect timing mark position.
Timing Position.
Crank Pulley in Timing (Safe) Position.
Timing Dots on Crank Sprocket.
Inlet Cam Pulley.
Exhaust Cam Pulley.
Pulleys with Locking Tool in Position.
VVC Rear Cam Pulleys. (This position is used for setting timing. Before cam carrier removal, the pulleys should be positioned with marks facing outwards)
Tips on cam timing
Before removing the belt, make sure that the engine is set to its safe timing marks. In this position, the crankshaft is at 90 degrees before TDC and all the pistons are half way down their bores. This means that the cams can be turned without damaging the valves. The cam pulley marks can be seen after removing upper belt cover.
Only turn the engine over using the crank pulley bolt or by rocking the car with it in gear. Do not turn it using the cam pulley bolts. Removing the spark plugs make this easier.
To undo the crank pulley bolt, do it before removing the belt and make sure that the cam locking tool is NOT in position between the pulleys or you could damage the belt or even bend the valves.
Never turn the crank with the head removed unless the liners are first clamped in position, as they can move. If the timing position has been disturbed, an alternative would be to refit the head with no cams installed so that the valves are closed.
The cam timing tool is only required to assist in final fitting of the cam belt. It is not required at any other time - if the cams move, this is not a problem with the crank in its Safe (Timing) position and they can easily be turned back when required.
Do not use the cam timing tool between the pulleys to hold them while undoing the bolts. The tool to use is either one that picks up on the pulley spokes or you can use some types of oil filter strap wrench (not the chain type) wrapped around the cam pulley.
Cam belts can fail internally and still look new on the outside. If a belt has been contaminated with any fluid (including water!) or pinched it should be replaced.
Final belt tension should only be set after rotating the engine a couple of turns by hand, stopping at the timing position.
Cam timing notch is on the front flange of the crank pulley as shown and positions the crank at 90 Degrees BTDC (Safe or Timing position).
The best crank timing mark is to line the mark between the two dots on the crank sprocket. The crank pulley has been known to slip round on the hub giving a false indication, as the pulley locating key is very small and it is possible to damage it when refitting, again resulting in an incorrect timing mark position.
David
Re: Timing 12 years 9 months ago #26021
-
Topic Author
- David Aiketgate
- Offline
- David
-
- mgf mk2 freestyle mpi 16" wheels, in Anthracite.
- Posts: 20139
- Thanks: 4388
Cam Belt Tensioning.
The original K series engine had a manually adjusted cam belt tensioner which is set using an external spring. This is then discarded after use to stop it jumping off into the cam belt! The tensioner on the mpi engine was changed at 97.5 MY to an automatic tensioner that self adjusts to compensate for wear after initial setting, but the VVC engines retained the manual tensioner. The cylinder head casting was changed to accommodate the different fixings of the new tensioner so they are not interchangeable.
Auto Tensioner.
Manual Tensioner.
Belt change intervals are 60,000 miles / 6 years (4 years on some models) for manual tensioners and 90,000 miles / 6 years for automatic. However, I think that most people accept 60,000 miles / 6 years as being safe for most engines.
There are three different cam belts available to suit the various engine / tensioner combinations -
143 teeth 23mm wide manual tensioner mpi.
143 teeth 26mm wide manual tensioner VVC.
145 teeth 26mm wide auto tensioner mpi.
Tensioning the belt.
After fitting the cam belt, the tension should be roughly set and then the engine is turned by hand for two revolutions clockwise. This both settles the belt and also gives the chance to check that nothing is going to lock up. Stop turning when the timing marks are lined up again and recheck that they are correct, then finally set the tension.
With the manual tensioner this is done by slackening off the fixings a little so that the spring tension can set the tensioner position then retightening the fixings. If the spring does not have a rubber sleeve fitted around it, it should then be removed.
The auto tensioner is set by slackening the fixing and then turning the tensioner with an allen key anticlockwise until the wire pointer lines up with the indicator notch. The fixing is then retightened.
It is normal for the auto tensioner position to change as the engine is rotated, but it should return to the set position when the engine is stopped at the timing marks.
The original K series engine had a manually adjusted cam belt tensioner which is set using an external spring. This is then discarded after use to stop it jumping off into the cam belt! The tensioner on the mpi engine was changed at 97.5 MY to an automatic tensioner that self adjusts to compensate for wear after initial setting, but the VVC engines retained the manual tensioner. The cylinder head casting was changed to accommodate the different fixings of the new tensioner so they are not interchangeable.
Auto Tensioner.
Manual Tensioner.
Belt change intervals are 60,000 miles / 6 years (4 years on some models) for manual tensioners and 90,000 miles / 6 years for automatic. However, I think that most people accept 60,000 miles / 6 years as being safe for most engines.
There are three different cam belts available to suit the various engine / tensioner combinations -
143 teeth 23mm wide manual tensioner mpi.
143 teeth 26mm wide manual tensioner VVC.
145 teeth 26mm wide auto tensioner mpi.
Tensioning the belt.
After fitting the cam belt, the tension should be roughly set and then the engine is turned by hand for two revolutions clockwise. This both settles the belt and also gives the chance to check that nothing is going to lock up. Stop turning when the timing marks are lined up again and recheck that they are correct, then finally set the tension.
With the manual tensioner this is done by slackening off the fixings a little so that the spring tension can set the tensioner position then retightening the fixings. If the spring does not have a rubber sleeve fitted around it, it should then be removed.
The auto tensioner is set by slackening the fixing and then turning the tensioner with an allen key anticlockwise until the wire pointer lines up with the indicator notch. The fixing is then retightened.
It is normal for the auto tensioner position to change as the engine is rotated, but it should return to the set position when the engine is stopped at the timing marks.
David
Re: Timing 12 years 9 months ago #26096
-
Topic Author
- David Aiketgate
- Offline
- David
-
- mgf mk2 freestyle mpi 16" wheels, in Anthracite.
- Posts: 20139
- Thanks: 4388
It my be useful to list some of the torque settings in here, off the top of my head:
Auto tensioner: 25nm
Crankshaft pulley bolt: ?
Camshaft pulley bolt: ?
Timing belt cover bolts: ?
Unless someone beats me to it I'll confirm them tomorrow
You mean like this list Andy?
David
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