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Discussion Starter #1
Hello , i recently picked up a alfa 75 right hand drive as i am in australia. The car has been sitting for over 10years so i thought i would change Timming belt water pump thermostat etc.
Now i have read alot of post on tensioners , and at first glance of mine i assumed it was a hydrolic tensioner(sorry about the spelling). But with closer inspection i belive the hydrolic tensioner should have another piston on the bottom (black tube thing) which would be located under the tensioner. and the top piston seems to be a threaded stud. So not real sure whats going on . Has this been converted to a mechanical tensioner ?? I have attached some pics and hope someone can give me some advice... Thanks for reading

Ps. I have not removed any part of the tensioner , the belt is still tight and the car seems to run fine. I dont want to remove anything untill im sure of what type of tensioner this is.



 

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Welcome, from a fellow Oz 75 owner. :)

Yes, your hydraulic (de)tensioner has been modified to be a fixed tensioner. That works fine; some people will suggest retensioning it occasionally, when the new belt stretches.

Indeed, there is usually a 'spring' attached below the original one, with a rubber sleeve over it (it's not a second piston).

:)
 

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mine has a similar arrangement - is accompanied by a plug in the oil feed to prevent oil leaks from the now surplus detensioner unit
 

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Discussion Starter #4
some more questions milano tensioner

thank you for your reply , its exactly what i needed to hear. I also have a few more questions , in this picture iv labled bolts 1 AND 2 just to confirm how to slacken tensioner and re tighten, So basically all i have to do is loosen bolts 1 and 2 and rotate tensioner away from belt to slacken belt. Then to tighten rotate tensioner towards belt and tighten bolts 1 and 2. picture is below
 

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? maybe the nut on the threaded rod (I've not adjusted it myself)
 

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ah, OK it clearly works differently to mine (or I have no understanding of how mine really works...)
 

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Discussion Starter #8
if anyone has see these welded before can they please give me some advice, thanks for all the replys so far . Its a great site for info.
 

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Ah, yours will be permanently 'fixed' then. I believe some are modified to have an adjustable bolt; yours is welded.

Nuts '1' and '2' merely hold the tensioner to the engine block (behind nut '1', is the oil feed to the original hydraulic version; your oil feed is presumably purposely blocked off). The bolts infront of the bearing/pulley secure the bearing unit in place, and also do not provide adjustment. All of the adjustment is originally from the piston, with yours replaced by a welded bolt.

I don't think your setup - with lack of adjustment - matters greatly. To me, it means the cambelt may not last quite as long, because it's under varying tension, sometimes normal, sometimes tighter than normal (or possibly looser); with a 'normal' (de)tensioner, it provides more constant tension because the belt is normally stretched when the engine warms up, and things expand. As long as you change it regularly (eg: 50K km or 3-5 years) I think you'll be right.

Alternatively, change to a spring-loaded version.

:)
 

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Ah, yours will be permanently 'fixed' then. I believe some are modified to have an adjustable bolt; yours is welded.

Nuts '1' and '2' merely hold the tensioner to the engine block (behind nut '1', is the oil feed to the original hydraulic version; your oil feed is presumably purposely blocked off). The bolts infront of the bearing/pulley secure the bearing unit in place, and also do not provide adjustment. All of the adjustment is originally from the piston, with yours replaced by a welded bolt.

I don't think your setup - with lack of adjustment - matters greatly. To me, it means the cambelt may not last quite as long, because it's under varying tension, sometimes normal, sometimes tighter than normal (or possibly looser); with a 'normal' (de)tensioner, it provides more constant tension because the belt is normally stretched when the engine warms up, and things expand. As long as you change it regularly (eg: 50K km or 3-5 years) I think you'll be right.

Alternatively, change to a spring-loaded version.

:)
the give away is no spring on the arm and the threaded rod.
 

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But with closer inspection i belive the hydrolic tensioner should have another piston on the bottom (black tube thing) which would be located under the tensioner
Hi 75srecko (75 wrecked-oh?),

First-off, yes, counter clockwise rotation (or downward force of tang) tightens the belt by pushing the wheel bearing against the belt (via off-center axis of wheel). Normally, the piston inside the de-tensioner has a big spring in it right under the top cap. There is another big spring (called the "reaction spring") that goes inside the black tube you mention that pulls the tang down as well. So both springs tension. It's the oil action that de-tensions by filling the cylinder under the piston forcing it upwards. http://www.alfabb.com/bb/forums/alfetta-gtv6-1975-1986/94819-de-tensioner-re-build.html#post583629

If I were you I would re-do that unit. Odd that despite showing no hestitation to weld things up, they didn't design this one properly. What they should have done drill suitable hole in cylinder cap, weld another nut of suitable thread (like the one presumably at the bottom) & then run a L o n g bolt all the way through (with lock nut), so that one could re-tension from time to time as the belt stretched. You do NOT want a fixed tensioner (or de-tensioner for that matter).

In my opinion, all you really need to do is weld-up the oil feed stud. The two stock springs will provide all the tension required if adjusted correctly.
 

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Discussion Starter #16
ah ok thanks for the link i have a much better understanding of how it origanally worked.
Ill keep you updated of how i go with mine. Thanks
 

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Just order a mechanical tensioner with the changeover kit from Jason at Alfissimo. They work fine. I am running one on my current Potenziata and on my my previous one, my brother has one on his 164 and I will be getting one fitted to my 164 soon. They are a genuine Alfa part, made in Canada, where probably most of the world's tensioners come from I suspect. My Alfa mechanic says they should have used them instead of the oil fed ones years ago.
 

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What they should have done drill suitable hole in cylinder cap, weld another nut of suitable thread (like the one presumably at the bottom) & then run a L o n g bolt all the way through (with lock nut), so that one could re-tension from time to time as the belt stretched.
this is a pretty accurate description of mine
 

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Discussion Starter #19
i going to try with the old tensioner first and see how i go, i will let you know how i go, still got to get some parts first. Thanks again to every body for the advice.
 
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