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Discussion Starter #1
Hi,

Had a chat with an Alfa specialist and he told me he stretches V6 cambelts overnight, after fitting, before fine tuning the cam adjustment/tension.

I'm not planning to do this on my 164 24v but am curious whether anyone else has. To be honest it could explain why after fitting my last cambelt it later slipped and had to be reset, with air-gap reset too.

Given the potential for damage this is quite an important thing to get right.
 

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Probably would't hurt to do that overnight process and rotate engine clockwise again and recheck air gap with 1/8" drill bit or square key stock and also try to insert 1/6" pin in holes in tensioner.

Reset tension if you can insert these go no go pins.

I think you still need to recheck belt tension after awhile of driving the car. Maybe NLT 10,000 miles.
 

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The belt manufacturers will tell you that modern belts don't "stretch." They have reinforcing cords that might eventually break if their stated lifespan is greatly exceeded or abused . . . . but not stretch.
 

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I thought, although I can't find it right now, is that Alfa? said not to reset the belt after it has been run for some length of time. I know Carlo won't do it.
 

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I work in an alfa shop and the belts def have run in period so we like to set them a little tight on the tensioner. At belt service intervals its common to see them loose so for what ever reason (and I think they stretch) its something to keep an eye on. The tensioners are also made from recycled Chinese newspaper. We often re-tension the v6 belts without any problem. The good thing about a 12v is you can check the belt when you check your oil.
 

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A hydraulic de-tensioner goes a long way towards not worrying about belt tension, reverse rotation of the engine, broken springs, etc.
 

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The 24v engine sort of has a Japanese designed closed loop sealed hydraulic spring loaded tensioner like used on some Ferraris. How is that for a string of adjectives?
 

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This sounds incorrect to me. The t belt tensioner is automatic. The belt has to change length with engine temperatures. This has to be a very small amount. If the belt really did stretch by any measurable amount the teeth would not engage in the cogs as the tooth spacing would increase at a different rate than the thermal expansion of the cogs.

I'd speculate a steel timing chain changes length by more than a fabric t belt.

The primary advantage of these t belts is the ease with which they accommodate thermal expansion of the engine. Pre stretching one of these belts (assuming this is even possible) would be a recipe for disaster in my opinion.
 

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Discussion Starter #9
Thanks everyone.

Think I'm going with Steve's thinking on this. Just setting the tension on a new belt caused slip and I had to reset it anyway. Better to let it stretch overnight and then reset it before slip can occur and risk damage.
 

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Was it the intake (front) cam on rear head that slipped? It has the least amount of timing belt teeth making contact with cam pulley by ill-designed system.

That is the one that jumped time years ago on Myron's after a repair shop had done the TB change for him. It ran like crappola with intake cam off 1 or 2 teeth.

I replaced belt and also freed up binding pivot point on tensioner bearing retainer pivot point.

I used factory tools aka weighted arm and cam lobe timing blocks.
 

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Well with the Zat tensioner on the 12V engine, the instruction is to set the belt deflection between the two top pulleys a certain amount and then check and reset it at 15,000 miles. Hence they do not really stretch according to Zat and it has been my experience as well that they do not (deflection stays the same when at the same temp). I have also experienced (using fixed tensioners) on other cars like the 944 Porsche, where a mechanic over-tensioned the belt to the point of being able to hear the whine from it. Well, they will whine forever until properly retensioned, so here again, a very similar profile belt design to the 164, and it doesn't really stretch to speak of. The later 24V car has an even stouter t-belt and I seriously doubt it stretches much either. A car that is in my driveway with a similar profile tbelt is the 240 Volvo. Factory procedure is to set the fixed tension and run then the car for 200-300 miles and then reset the tension, which has seemed like a waste of time and effort whenever I have followed that instruction. I never seem to be able to notice any movement of the tensioner on the retension, but hard to tell as the cover is still on when you do this. Then again, modern tbelts are probably less prone to stretching than they used to be, just due to better manufacturing than when they first started making these things in the 1970s and 80s on a large scale. I would guess they are better than the belts made in the 90s as well. Just speculation on my part there. I really don't think they stretch, but if the guy feels like he is doing a better job letting it "stretch" overnight and he feels like it is making for a better tbelt change, than I wouldn't argue with him. It certainly won't hurt anything, but it is debatable whether it is really making any difference. I don't think the retension is necessary on the 240 either, but I follow the instruction just because the manuals say to do it.
Charles
 

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I cut the old belts at different distances run ( 30-50000km) and compared with the new belt length . The old were not stretched. After 10-15000 km belt becomes " dry ".
 

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At the risk of maybe beating this one to death I checked my 1991 ARDONA shop manual. There is no specification for re-tensioning the timing belt after installation. There is a specification for checking the timing and re-setting the tensioner but no time or mileage interval.

I am now on my fourth t belt and none of them has been re-tensioned after the initial install, as far as I know. If any were I was not charged for the service.

As for pre-stretching a new belt I ask how does the mechanic decide what pre-tension to apply to perform this step and for how long? It is not recommended to refit a t belt that has been removed from an engine. Surely the correct installation of the belt tensions it correctly right from the get go? What possible advantage could there be to tensioning the belt off the engine?
 

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That's my feeling as well. I know they have not been retensioned on my two 164s, since they generally don't see Carlo between belt changes.
 

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Discussion Starter #15
All I can add is my 24v belt slipped days after installing. Steve, it was the rear cam that jumped about three teeth. Ran bad.

I reset it in the carpark rather than driving on it, same belt, and it has been perfect ever since - 6 years and 40,000 miles later. The stretch tension on it is just the regular tension and its a long belt so the mm or so of stretch that makes it go loose is unlikely to show when next to a new belt.

Given what happened, there is no way I will ever do a 24v belt change without rechecking the tension 24 hours later. The cam contact with the belt is too short for it to be any less than perfect.

Which is all ironic as all my understanding of cambelts before this was never retension as it could be too tight and cause a snap. Fiat X1/9 for example. Bent valves in both cases if it ever happens. Ooooch.
 

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I think it is more important to verify TB tensioner bearing 60580238 idler arm pivot support point is free to pivot on 60580232 pivot pin and free of any binding or corrosion and lubed properly when you change belt and that that 24v Tsubaki tensioner is in good shape with no free play in piston.
 

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I am about to re check my timing belt on my '94 LS in the next week or so and I am a bit confused.
Isn't it recommended to do this check?


The belt was installed by me with help from friend in June '13 and I have about 6 K on the new belt. Car has been running fine.

My progress so far-
Gravel guard and strut out, next sprakplugs out [ so easier to turn engine over]

and finally timing belt covers. They are no fun to remove.

My plan is to re tension both aux and timing belts. I don't think is can hurt to do this. Plus check what Steve has mentioned above.


Bye the way in-

First thing in noticed so far was a bit of rubbing on the gravel guard from the inner edge of the tire. I installed a new duplicate steering rack 5speedLS and matched the thread length before installation. Then had it aligned. I imagined that the mechanic in the alignment shop adjusted one side to get his reference mark. What is the fix? Take the car back and get it re aligned.

Thanks

Frank
 

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I never take the strut out. The covers are not so bad with the 1/4 inch snapon 10mm universal socket, its a must have for LS work in my view.
 

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Discussion Starter #19
I am about to re check my timing belt on my '94 LS in the next week or so and I am a bit confused.
Isn't it recommended to do this check?


The belt was installed by me with help from friend in June '13 and I have about 6 K on the new belt. Car has been running fine.

My progress so far-
Gravel guard and strut out, next sprakplugs out [ so easier to turn engine over]

and finally timing belt covers. They are no fun to remove.

My plan is to re tension both aux and timing belts. I don't think is can hurt to do this. Plus check what Steve has mentioned above.


Bye the way in-

First thing in noticed so far was a bit of rubbing on the gravel guard from the inner edge of the tire. I installed a new duplicate steering rack 5speedLS and matched the thread length before installation. Then had it aligned. I imagined that the mechanic in the alignment shop adjusted one side to get his reference mark. What is the fix? Take the car back and get it re aligned.

Thanks

Frank
Hi,

Agree no need to take out strut. Never found it an issue to work around.
Timing belt covers easier to remove if you take the water pump pulley off first.
Tyre scrub on wheel arch liners is normal.

As for the need to recheck timing belt tension, it can't hurt to make sure it hasn't gone very slack. Personally, right or wrong, I am going to set mine and then reset it after a day or so.

Good luck
 

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"First thing in noticed so far was a bit of rubbing on the gravel guard from the inner edge of the tire"

Uh huh. It would be rare to find a 164 without that.
 
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