ALFAGTV6.COM

[Lucio]

Perhaps this is a frequently asked question...if so, I beg your pardon

The hydraulic tensioner on my GTV6 doesn't seem to work (though the previous owner claims it's brand new).
Hence I'm considering buying a new one (>230 euro!!! ).
Someone suggested me to avoid the old hydraulic type and choose one of the latest V6 tensioners instead.

Pros & cons? Is it reasonable?

Thanks & happy motoring
Lucio

[MD]

Lucio

There are many and varied opinions about this item.
I run a 164 motor in my GTV and use a mechanical tensioner that has the tension set at the time of the belt installation. Works perfectly.
The only caution is that you need to keep low revs until the motor is warmed as the final tension is actually done by the expansion of the motor due to heat.
In practice, this is a good thing as you should always warm the motor before opening up with big revs if you intend to have your engine last.
I know others will have a different view...

[Mats]

I would say thet the expansion of the engine does just about nothing for the tension of the belt, unless you have a belt made out of unobtanium alloy that has a E-module near steel but the flexibility of rubber..

[David]

Mats,
I tend to agree with you. The hydraulic de-tensioner will go into de-tension mode just cranking the engine with the starter so on a cold engine the belt would be too loose once the engine is running. My "theory" on the purpose of the de-tensioner is simply to keep the belt tension the same when the engine is stopped as the tension required when the engine is running.

I have rebuilt the hydraulic units on two 2.5 GTV6 motors and on my 164 3.0L and have not had one leak. My "theory" on the cause of the leaks is, if the piston shaft is in good condition and all gaskets, etc are installed correctly, the weakest point is where the piston shaft seal sits in its groove. They are not a tight fit and don't seem to have any proper sealing method for the outer part of the seal. My solution is to fill the groove with silicone sealant and then insert the seal. The excess sealant comes out past the seal. Clean this up carefully and let it cure before final assembly.

The photo shows the seal in place with blue silicone sealant.

David

[Lucio]

Mmmmh, so the newer tensioners are not OK with an old 2.5 V6?

The old hydraulic one does have some oil leak but the problem seems that it stays "locked" in one position (or so my mech guy says).

Lucio

[Glen B]

Lucio,
The "Belt stretcher housing," (metal casting) is in fact locked in one place when you are happy with the pre tension , but the piston/plunger is free to press against the "Belt stretcher plate" which holds the pulley. The pulley is on an offset hub so it acts like a cam/lever.
Along with some very strong springs, and added oil pressure the faster it goes the tighter the belt gets, but when the oil gets hot and the block expands some, then the pressure is less. As much as needed. It's a neat system..

David ,
"They are not a tight fit," where you used silicone, I decided to put a thick "O"ring inside of that rubber seal between the rubber scrapers. Figured that since it was always going to be soaked in oil, it might not wear out or bake as fast as the original edges. It has only been 2300 km, so far so good. 27 000km to the next TB and water pump and..and.......

Any idea of puting grease in there was only for the install, it would melt and dissolve with hot motor oil after a few cycles of pressurizing that cylinder at run cycle and relaxing when off.

The only tricky thing was getting that timing belt back on. A handy tool for slipping the belt back over the idler pully , The spine of your socket holder set, cut down to about 7" it's perfect.( some one else may have mentioned that somewhere)

Glen

[Lucio]

Lucio,
The "Belt stretcher housing," (metal casting) is in fact locked in one place when you are happy with the pre tension , but the piston/plunger is free to press against the "Belt stretcher plate" which holds the pulley. The pulley is on an offset hub so it acts like a cam/lever.
Along with some very strong springs, and added oil pressure the faster it goes the tighter the belt gets...[snip]
Glen

This doesn't seem to happen on my TB. The belt tension doesn't increase with revs.

Lucio

[Glen B]

Hi Lucio,

have you had this mechinism off of the engine yet? Does it still have the original hollow bolt/stud that feeds oil into the cylinder? Is it getting oil. Does it have the "O" ring around the piston , to hold any pressure, and is the small hole in the bottom of the unit clear to allow any blow by oil to return to the sump. Otherwise it maybe in an oil lock state where she may not move. Or maybe an extra washer on the pulley that is stopping it from adjusting around its hub. There is a thick one on there but only big enough to cover the hub stem and a little overhang.
Just a few straws to chew on
Glen

[Lucio]

Hi Lucio,
have you had this mechinism off of the engine yet? Does it still have the original hollow bolt/stud that feeds oil into the cylinder? Is it getting oil. Does it have the "O" ring around the piston , to hold any pressure, and is the small hole in the bottom of the unit clear to allow any blow by oil to return to the sump. Otherwise it maybe in an oil lock state where she may not move. Or maybe an extra washer on the pulley that is stopping it from adjusting around its hub. There is a thick one on there but only big enough to cover the hub stem and a little overhang.
Just a few straws to chew on
Glen

Dear Glen,
the Alfa mech will be dismantling it soon. He will change all the oil seals and rebuild it. Let's see what happens.

Thanks to everyone
Lucio