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Discussion Starter · #1 ·
This is one my dad and I can not work out. Its on the rear bank inlet.

How does a cam skip forward a teeth or two?

The belt feels tight enough. It happened on start up on a dampish day which is very similar to when it skipped a tooth (we cant remember but as it didnt raise any queries we think the cam must have gone backwards that time) like this less then a year ago.

It doesn't make sense at all, if a belt slips it leave the cam behind, not sending it ahead!

Here are some pics:

Rear bank, misaligned timing marks:


Front bank, correct timing marks:


Rear bank, exhaust cam lock, fits as it should:


Rear bank, inlet cam lock, does not fit!



Front bank, inlet cam lock, fits as it should:


Front bank, exhaust cam lock, fits as it should:


Any ideas?
 

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Well this post didn't provoke much in the way of a response i.e. nil !
Anyway I thought I would update on the progress anyway.
After getting some good steers from AlfaBB and also closer scrutiny of some old posts here on AO it seems that the cambelt retensioning procedure is not a simple as I had assumed it to be. Besides the eccentric tensioner wheel there is also a plunger which is hydraulic. This has to be depressed (very difficult) and pinned before then tensioning the belt eccentricly. It takes time to get right so the pin can be extracted easily but eventually I managed it. Hopefully this will prevent any further creepage of the cams - we will see !! Like to say I am now driving it but the battery is flat - B*gger
 

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I had a similar problem when I re-started my engine immediately after stalling. I was advised that the belt had slipped because i hadn't allowed the tensioner to adjust. What I should have done was wait 10-15 seconds after stalling before attempting a re-start. It sounds like you've sorted the problem anyway but if you're not already doing it already you might also want to bear this in mind.

Gerlad
 

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Sorry I couldn't help you guys BUt after reading this I'm glad my V6 24v engines are in the 166's.
Top tip for 164 users tho.
Pomeo
 

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Sorry I didn't see this sooner. Similar thing happened to my 164 about a year ago. The pin had basically got stuck into it's cilinder/housing and wasn't tensioning the belt (got a pic somwhere too), therefore the banks basically 'open out' and you get your off timing, usually more on the rear bank than the front. No damage done as it was not enough to bend valves but the belt could have slipped if I had insisted cranking over or tried a bump start.
 

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I take it this tensioning system was modified for the 166 engines.
Pomeo
 

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Yes, in 166 the oil pump is chain driven inside the main block, on 164 oil pump is driven by toothed belt, so belts route is different and there is more strain on the belt.
On 164 there this complicated belt tesioner (spring, oil, ...), on 166 there is only spring loaded eccentric tensioner.
 
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