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Zetec Cam Timing
AntonUK - 4/3/18 at 03:01 PM

I am just refitting the cam belt after a head change and have come across an issue.

As per the haynes i set the timing positions with crank at TDC and the locking bar in the cams. Loosen tensioner, rotate 2 times and tighten the tensioner.

But... at one point in the engines rotation a distinct slack in the pulleys appears. It is only in one area of rotation it is tight at every other point...


What have I missed?

chris - 4/3/18 at 03:41 PM

do you mean you are rotating the engine with the tensioner loose

obfripper - 4/3/18 at 04:29 PM

The tension will dance about with the tensioner bolt slack, it wouldn't be the first time i have seen incorrect instructions in the haynes manual.

Start with the cam sprocket bolts loose enough to turn the pulleys, the tensioner allen key wound back (iirc clockwise) to the stop and the tensioner bolt lightly tightened to hold this position while fitting the belt.

Then with the crank timed up on tdc and cams locked with the bar, you need to slacken the tensioner bolt to allow the tensioner spring to operate, tighten the cam sprockets(while counterholding with special tool) , then tighten tensioner and turn crank over twice to tdc.
Then refit the camshaft bar. If it doesn't fit then slacken the camshaft bolts and repeat the above process until the bar fits satisfactorily.

Dave

chris - 4/3/18 at 04:41 PM

if you are turning the engine over with a slack tensioner then the tight spots are probably the the valves making contact with the pistons

AntonUK - 4/3/18 at 06:01 PM

quote:
Originally posted by obfripper
The tension will dance about with the tensioner bolt slack, it wouldn't be the first time i have seen incorrect instructions in the haynes manual.

Start with the cam sprocket bolts loose enough to turn the pulleys, the tensioner allen key wound back (iirc clockwise) to the stop and the tensioner bolt lightly tightened to hold this position while fitting the belt.

Then with the crank timed up on tdc and cams locked with the bar, you need to slacken the tensioner bolt to allow the tensioner spring to operate, tighten the cam sprockets(while counterholding with special tool) , then tighten tensioner and turn crank over twice to tdc.
Then refit the camshaft bar. If it doesn't fit then slacken the camshaft bolts and repeat the above process until the bar fits satisfactorily.

Dave


Thanks that helped, I took a step back, had a cup of tea and revisited it. Ive managed to sort it now. I needed to undo the inlet sprocket and re-tighten, in turn it moved the slack to the tensioner.


quote:
Originally posted by chris
if you are turning the engine over with a slack tensioner then the tight spots are probably the the valves making contact with the pistons

I never said the engine was tight?

[Edited on 4/3/18 by AntonUK]