156 1,6 exhaust cam pulley question - Alfa Romeo Forum
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(Post Link) post #1 of 5 Old 22-05-10 Thread Starter
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156 1,6 exhaust cam pulley question

Hey everyone

When changing the cambelt, the procedures say you have to loosen the bolt on the exhaust pulley. I donīt get that part, because as far as I can remember the pulley has a pin and the shaft a groove which holds the pulley in place on the shaft?

The reason for me asking is that last time I replaced my belt, I didnīt loosen the bolt on the exhaust pulley. I did have to turn the crank a little off TDC to fit the belt (I know, done is done, dont spend time telling me that its stupid etc. etc.).
After that the engine runs rather sluggish in the low revs (no low end torque).

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Slacken the bolt and you will find it has movement. Always follow the workshop manual
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Thats because you have altered the cam timing in relation to the crank by moving the crank rather than loosening the cam pulleys (probably too advanced if it flat at low revs) . Bet the fuel consumption isnt that great either. The cam pulleys are not keyed - just a tight fit on a cone. You are lucky that the valves have not hit the pistons...they still might at high revs if youve not driven it hard yet. Also there are potential emissions issues come MOT time. Im afraid you need to start again and do it properly to get your performance back.
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Yes, there is a key on the exhaust pulley, but it allows about two-tooths of rotation. (The V6 engines have no key at all).

When I fitted my belt the first time, it all went well except that I forgot to tighten the pulleys before removing the camlocks and turning the engine over. And also, there had been the small matter of the white lines on the belt lining up with the exhaust pulley but not with the crank pulley.

The second and third times, I found that I could not tension the belt without the crankshaft moving.

Finally on the fourth time, I discovered that the crank pulley has a second mark (behind the balance belt pulley, so won't be as hard to find on the 1.6). I therefore lined up the white lines on both the exhaust cam pulley and the crank pulley. And then, I had no problem tensioning the belt. In other words, even when the pulley is slackened, it is still important to get the belt on exactly the right tooth of the exhaust cam pulley, because of the limited movement available for tensioning.

So I'd suggest to try again and also this time, make sure to line up the marks on the belt, to ensure you have the exhaust cam pulley on the right tooth

And as for knowing which white lines to use, you'll find that one white line is between two teeth (which is for the exhaust cam pulley), while the other white line(s) are in line with a tooth.


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Thank you for the answers. It was the movement with the key in place I wasnīt sure of. Now I can do it again, knowing why to loosen the exhaust pulley . @ AlfaItalia : Youīre right, the fuel economy is rubbish.
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