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Discussion Starter #1
Hi guys,

Im new to the forum but not to the ever frustrating world of Alfas.

I am a long way into a complete restoration/modification of a 75 which i am transplanting a 164 24v engine into.

The engine is in the process of being re-built and i would like to convert the cam belt tensioner to a mechanical one. The problem is i have no idea which one to use and what needs doing in order to achieve this?

There seems to be a lot of snippets of info out there but nothing definitive. If anyone has done it could you please post your findings below prefferably with pictures if possible. Thanks in advance

Aaron
 

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I don't think I would do this, as the tensioner on the 24V seems to be very good, and really long lasting. I see nothing good coming from such a change. I've actually not heard of anyone doing this, but maybe someone has, I don't know.

It's the 12V engine where people fiddle with different tensioners for that timing belt but it never came with the 24V engine style tensioner.
 

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Discussion Starter #3
I don't think I would do this, as the tensioner on the 24V seems to be very good, and really long lasting. I see nothing good coming from such a change. I've actually not heard of anyone doing this, but maybe someone has, I don't know.

It's the 12V engine where people fiddle with different tensioners for that timing belt but it never came with the 24V engine style tensioner.
The main reason for wanting to change is that they are very rare now and they carry a premium on cost!! Unless there is somewhere i dont know about selling them cheaper?
 

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I would ABSOLUTELY do it - 100% I've been running some of my 24 valvers this way for YEARS and it works GREAT! You just have to have a VERY good "feel" for that static belt tension!

All you do is install the entire stock 24v system with the old tensioner housing gutted! Set the tension so that the gap is taken up (the swivel "foot" of the tensioner bearing will ride flat against the tensioner housing.)

Get a second set of eyes on that belt tension. Set it statically and forget about it. The new belts are VERY even and I have had zero issues. YOU HAVE TO GET THE TENSION JUST RIGHT THOUGH! ASK FOR ADVICE!

Make sure though that EVERYTHING ELSE in the system is BRAND NEW (the belt itself, the tensioner PULLEY and BOTH idler pulleys!)

Replace the belt every 3 years OR 36,000 miles - whichever comes FIRST. DO ALL three pulleys (tensioner pulley and the two idler pulleys) every 36,000 miles - regardless of time (within reason...)

Make sure to check the bushing inside the head that the oil-pump drive rides in, for excessive play WHILE the heads are off!!!
 

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Discussion Starter #5
I would ABSOLUTELY do it - 100% I've been running some of my 24 valvers this way for YEARS and it works GREAT! You just have to have a VERY good "feel" for that static belt tension!

All you do is install the entire stock 24v system with the old tensioner housing gutted! Set the tension so that the gap is taken up (the swivel "foot" of the tensioner bearing will ride flat against the tensioner housing.)

Get a second set of eyes on that belt tension. Set it statically and forget about it. The new belts are VERY even and I have had zero issues. YOU HAVE TO GET THE TENSION JUST RIGHT THOUGH! ASK FOR ADVICE!

Make sure though that EVERYTHING ELSE in the system is BRAND NEW (the belt itself, the tensioner PULLEY and BOTH idler pulleys!)

Replace the belt every 3 years OR 36,000 miles - whichever comes FIRST. DO ALL three pulleys (tensioner pulley and the two idler pulleys) every 36,000 miles - regardless of time (within reason...)

Make sure to check the bushing inside the head that the oil-pump drive rides in, for excessive play WHILE the heads are off!!!
Thanks for the advice.

Which tensioner did you use? Was it the same as what is used on the 156/147 V6?

Do you have any photos or a thread on here i could see?
 

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Discussion Starter #7
Reread junglejustice post and he tells you use original tensioner . Once you look at your tensioner you will understand .
Think i know what you mean, Pictures would really help though, Its not me building the engine as my confidence isnt high enough.
 

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Ok, so someone has tried it, evidently with some success, although tricky to get it right? If you get it wrong... $$$$

Still, I haven't heard of anyone having problems with the OEM tensioner, except for getting it set wrong?

Goats does his own 24v belt changes, what does he think?
 

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Who's building your engine ? You can even leave the guts in the tensioner but compress the pin back in and put a tiny pin through the housing into the main adjusting pin . Now if you're not confused now you never will be :) then set the tension and lock it . Then remove pin . The most it will protrude under detention is about 1mm so nothing to worry .
Its same procedure as what jj was saying above but you keep the guts and lock it in minimum position . One rule is never even rotate these engine backwards as the love to jump teeth and this occurs when you put them in your 75 and some clown rotates the prop in wrong direction when changing a coupling .
 

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If the issue is cost, then use the Ferrari part (exact same part BTW) and its cheaper than the alfa part. The tensioner is called a Tsubaki type and used in a lot of cars/trucks-- even my Toyota Tacoma uses one. They are typically very reliable, last 20+ years, etc. You can even get a used one that you can test out of the car to see if its good.

I've never considered going without one, but where I live its possible I suppose as we don't get huge temp swings in ambient here-- but if you live somewhere where it gets really cold (ie 20 F ) then it would get dicey I think. Since they are (relatively) cheap (300 bucks +/-) I just never considered it, and I have never replaced one on any of the 24V cars I;ve had or helped with. I don't really see the advantage in ditching it I suppose....If it were possible to ditch it, I think Alfa would have done so given the numerous TSB;s that are associated with doing the belt work....???
 

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Two seperate things - the tensioner (oil-filled device that has an inner piston/pin that pushes out and creates more tension as the cast iron housing heats up...

And then

The tensioner pulley (with a bearing inside) that is mounted on a swivel and that is tensioned by that cast iron tensioner...

Here's the thing - you can leave the guts in, but you have to be 100% SURE that it is shot. If you set nice tight mechanical tension statically on the belt and that tensioner still works fairly well, it will push the tensioner pulley out and create too much tension and eventually break the belt and bend valves...

And even better way is to weld a couple of nuts on to the tensioner (one locking) and thread a bolt up the center to create a mechanically adjustable tensioner...

Be carefull - the guts are basically held in by a stupid clip at the bottom that can very easily pop out - don't use the guts as a stop - use the housing as a stop!
 

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I hear you, but I'm still not sure what the point is, if the stock one has demonstrated that it works well for years, and the design has worked well for millions of vehicles.
 

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JJ is 100% correct . Rather take guts out .
Cost is never the issue on these , its the supply of a new one which you don't get !
These tensioners due fail just like all parts and should be replaced according to Alfa Manual which I assume was based on their design at every cambelt change . This I doubt many customers did .
 

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Del, they do fail (300,000+ miles on 11 of these cars over 15 years...) Only one of those (my first one), was a 12 valve - the rest were all 24 valvers.

They do fail and that's why I ended up owning as many of them as I did (rescue projects.)

To be honest though - and to your point DEL - most of those failures weren't necessarily from the tensioners failing, but more from the tensioner pulleys failing, or the idler pulleys failing, or the belts failing, but still - I have replaced MANY of these blody tensioners over the years because they don't hold the tension and then on deceleration, the belt skips.

Or, once cold - the tensioner retracts too much for where the tension was set (bad mechanic in that case, but still), the tensioner retracts, the belt slacks and upon the next start-up, or roll-back / bump in gear, the belt skips!

You guys will **** yourselves if you see what I have seen (with covers off for thousands of miles) on 24 valve motors - over the years observing the belt tension, what happens cold, what happens warm, and where that slack goes and rests upon shut down...

Better leave the covers on - what you don't know won't hurt you. :)

NEVER use the factory cantilever tool to set tension. LEARN how to do the 24 valve correctly - best experience with these cars once you have it.
 

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Not going to argue with you, I just go by what my mechanics says, recommends, and does. I'm sure many of your failures were not the tensioner itself, as you say, but being a mechanical device (although quite simple), there is the potential. That design by that manufacturer is used on millions of cars without apparent failure.

I do see them for sale on a couple of sites. I suppose one could buy the Ferrari version for less, or even the others as listed, and keep it in the garage for the next belt change.

I cannot find the discussion on that Ferrari substitute in the BB search (don't like that search set up). Anyone have a reference?
 

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They do fail but when they fail they do not cause issues. I say keep it the way it is. When they fail they have lots of miles on them already. I have seen many with 130K miles on them with original tensioner still working properly. They are pretty robust and by the time it does fail I will still have them in stock for a reasonable cost.
 

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That's my feeling as well. Carlo just hasn't seen a problem, has never had a failure in his 24V set ups. Good enough for me. Did find the Ferrari number, but Jason does have them for a reasonable price. May some day go with him on that.

Got about 30k miles to go on the belt that is in there now. Last belt ran 45k miles and 6 years before changing, belt looking fine. Still the original tensioner at 105k miles. Yeah, could have changed the belt sooner, I guess; however, I think the 30k mile limit is conservative, plus the miles on the belt are almost all pretty steady state rpms on the highway.
 

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The engine is in the process of being re-built and i would like to convert the cam belt tensioner to a mechanical one.
Hi !
I drive Alfa every day in the year it is about 25000km. 9 years ago I convert the camshaft belt tensioner. I did not like the price and availability of purchase.

I change the belt every 50000km. If you are satisfied with this, I can try to explain how I did it. My English is not very good :(
 

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I had one failure on my 164 when the car was pushed back while it was in gear and belts jumped a tooth on left bank . Their was to much variation on that tensioner . My garage could not source a new tensioner so they then gutted the tensioner and threaded it with bolt through it and locknuts . The car ( tensioner) did another 80 000 miles with the regular belt and pulley service . I personally think it was not their best design( the armchair expert ) even though thousands of engine were made but I had no such problems with the modern 24v motor which Alfa did upgrade the tensioner . Just because Alfa made it does not mean its great design , just look at the early GTV 6 hydraulic tensioner that sprayed oil everywhere even on low mileage cars . Ironically the upgrade on that tensioner with spring type also had their own issues of spring snapping . This tensioner came from 155 and its range of motion was less on that motor than on the GTV/75 motor Apparently this is what my mechanic told me .
 

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Could you please explain?

Hi !
I drive Alfa every day in the year it is about 25000km. 9 years ago I convert the camshaft belt tensioner. I did not like the price and availability of purchase.

I change the belt every 50000km. If you are satisfied with this, I can try to explain how I did it. My English is not very good :(
Hi Evgeny,

I have seen your lengthy trips in that 24V 164 so could you please share with us comprehensively how did you did this? Especially would like to know how the tensioner was made and the tensioning procedure used? (whether you used the arm and the weight tool?) And your belt & pulley change/adjustment intervals? :nerd:

Many thanks,
Tharanga
 
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