164 24v cam belt tensioner/tension - Alfa Romeo Forum
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(Post Link) post #1 of 3 Old 05-10-14 Thread Starter
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Help 164 24v cam belt tensioner/tension

Hi just set the new belt and tensioner to the correct settings that I have from the alfa BB site but when I rotate by hand some times the tension appears to be to tight and other times it seems ok it's never showing as too slack .

Is this normal or is there something amiss?
I have wound it round and already reset it 3 times and left it under tension over night.
Re-checked this morning and the tension seemed a little tight then wound the engine round 6-8 times and some rotations it seems spot on and others a little tight.
Anybody done this and should it be totally consistant.
The tensioner is in good order and the pulley is good and tightened properly.
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Sounds pretty normal TBH. You will always see some variation in tension as the engine moves round the cycle simply because at hand-turn speeds, the way the cams are pulled then pushed by the valve springs is very susceptible to where you happen to stop while turning, how well lubricated one follower may be, how freely it moves on that occasion, all sorts of stuff. If you looked at it with the engine running you would still see it 'chatter' but at a much higher frequency of course, so it looks less dramatic.

The point at which you set tension is the only 'defined' one, so as long as it is more or less right, most of the time, at TDC, and only if you stop at the right spot rotating the correct way (i.e. don't back up to it) then all is well. Other engines use different methods to try and avoid this problem I think. The MX5 engine for example has different positions for timing & tensioning.

A wee bit tight is OK, not too tight though - the tensioner needs to accomodate quite a bit of block and head expansion, so it's gets tighter as it hots up, using up that 'tight-side' adjustment space. On the old 12V motor they actually call the hydraulic one a de-tensioner.

A pointer thickness or so of variation is fine. Much more than that, think about adjusting it a gnats.

All IMO. YMMV!
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(Post Link) post #3 of 3 Old 06-10-14 Thread Starter
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Thanks Chris I will check once more if it stops raining .
I think I've got it right just don't remember it varying last time I did it .
It doesn't move out of the setting gap just varies when as you say is at different positions in it's run.
I took the follower arm off and cleaned and lightly regreased it and think it is moving a lot more freely than it had been.
Just being paranoid I think but glad to have a second opinion.
The tension on the belt across the cam pulleys and on the crank to the pulley run seems good .
At TDC the pin goes through the tensioner setting hole ok and the gap on the arm to tensioner body is good too.
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