Strange noise after replacing the cam belt on 3.0 V6 - Alfa Romeo Forum
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(Post Link) post #1 of 12 Old 01-05-11 Thread Starter
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Strange noise after replacing the cam belt on 3.0 V6

Over the weekend i have tried to replace cam-belt and i have failed !
Along with cam belt i have replaced - idlers, tensioner and water pump.
I have used as instructed cam locking tools and DTI, everything was going according to the plan, after fitting new cam belt i have turned the engine several times before i started and everything was going around smoothly and without noises, after that i have turned engine with starter motor to check the compression and again all fine. So i have put everything back together and this is what my engine sounded like:
http://www.youtube.com/watch?v=BWdAfKBZkFc

after that i have took everything apart and used a locking tools to lock the engine and double check everything and all looks fine, just as it should. Belt has perfect tension everywhere.
But now when i turn the engine i can hear metallic "ding" you can hear it here:
YouTube - Alfa 166 valve

Could anyone tell me what went wrong ? I cant see the fault!

Last edited by P3rLuS; 01-05-11 at 20:48.
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The "engine sounds" video isnt working - could you re-post
 
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The 'ding' noise appears to be directly related to the positon of the crank, rather than a cam (IYSWIM), as it happens at the same two points of the cam rotation, looking at those lobes you had the camera pointing at, so the same place on the crank every rev....but what's making it.....it has the sound of a valve spring 'twanging'....but unless there are bent valves on 2 opposed cylinders (say 1 & 5, 3 & 4 or 2 & 6 ) ...don't know.

...and sad to say, it sounds terrible when running but it does seem to sound smooth/regular......which is weird.

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Have you double checked the tension on the cam belt, i and a couple of other members on here have all had similar problems, once you are sure that you have the cams locked in the correct position and the crank also at TDC, you need to slacken your 4 camshaft pulleys of so they can turn freeley, then put the belt on from front towards the back, then with the crank locked you need to set the tension then tighten the cam pulleys back up if the tension is a little slack you do get a similar noise which appears to dissapear after a short period of time of the engine running. But start it from cold and it does it again. Good luck i hope you get it sorted.
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I still did not got it sorted...
My cambelt was a bit loose, i have re fit the cambelt but the ding noise is still there, i have checked the compression on all cylinders and its perfect 14 on every single on so it means that there is no bent valves.
But im still scared to fit everything back on

I have taken few pictures to keep track of progress:
https://picasaweb.google.com/p3rrla/...eat=directlink
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Could it possibly be a spring in the DM flywheel????? Can you try pressing the clutch pedal as you rotate the engien maybe??

Good to hear compressions are OK, so that eliminates valves....

That photo of the tensioner - that was before you fixed the tension, yes?
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Bad valve timing
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(Post Link) post #9 of 12 Old 12-05-11 Thread Starter
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Quote:
Originally Posted by ChrisS View Post
That photo of the tensioner - that was before you fixed the tension, yes?
Its the picture after rotating the engine about 40 times, when i was tigting the tensioner up it was spot on on the mark, but it now goes up and down - i guess thats normal ?
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Quote:
Originally Posted by ChrisS View Post
Could it possibly be a spring in the DM flywheel????? Can you try pressing the clutch pedal as you rotate the engien maybe??
You were right, it was a spring ! when i pressed the clutch sound disappeared. I have put everything back together and engine sounds fine but is misfiring so i think im on the right track.

BTW are inlet intake pipes and coil packs interchangeable? - i might swap something around maybe.

Last edited by P3rLuS; 12-05-11 at 23:43.
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Hah! Confess that was a total guess!!

Inlet runners and coil packs are completely interchangeable. Well, of course, there are two shapes of inlet runner....but no problem swapping within a shape IYSWIM.... I guess a slight air leak on one cylinder might be the cause, given you've hadf to strip it a few times. Have you got an OBD reader? Might be able to narrow it down to one particular cylinder if you have.

Indeed, the tensioner will move about quite a lot as you slowly rotate the engine - the tension round the belt changes a lot as individual cams open and close valves. One point they are pulling, the next they are pushing, so it's all over the shop. Should steady down as the engine runs, and should be close to the reference mark.
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(Post Link) post #12 of 12 Old 13-05-11 Thread Starter
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Its all running fine now !
Just came back from test drive.
It took me 2 weeks to replace the cam belt! shocking!

Thank you all for help and advice !
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