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Discussion Starter #1
I am in the process of converting back to the orignal hydraulic tensioner (detenisioner) on my 83 CA GTV6. I need to replace the solid stud with the hollow stud. So far I cannot get the thing to move. I have tried double nutting, blue loctiting the nuts to the stud and a stud remover from autozone. No movement. I can't get heat on it as the torch flames up when inverted (engine is in car). My next step is to PB blast the stud and red loctite the nut on and trying to get it off with a socket. Any ideas how to get the stud out? Terry
 

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Got the stud out. Let it soak in multiple applications of PB blaster for 2 days. I then attache the nut to the stud with red locktite. and it came out. As far as converting there is quite a bit of that on this and the 164 board. I think it is the better solution. Keep in mind the mechanical tensioner was never adopted in Europe. I had Jason at Alfissimo rebuild a used one I got. Since I am have the head off due to a valve hitting a piston due to a failed tensioner it was the opprtune time to do the reconversion.

Terry (orginal owner 1983 CA GTV6)
 

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Interesting Terry, Most anecdotal( I don't have real stats) info indicates the hydraulic 'detensioner' has more issues which is why Alfa provided the mechanical spring upgrade. And there is a solid tensioner device too. others have designed their own like the SA engine builders.

some have blocked oil flow and installed a strong spring inside the alfa detensioner unit with success. acts like a permanent tension unit. Coil spring less prone to failure vs concentric spring?

I usually convert or add new belts and spring tensioner on my rebuilds and have not had a failure..yet. But, the spring mechanical ones are know to fail too.

And then there is the issue of leaks and replacement parts...

Personally, I would like to adapt the mitsubishi 4g63 hydraulic tensioner to the gtv6. It would not take much work to fab a mount for it. and the 4g63 is a 4 banger OHC engine w/cast fe block and aluminum head experiencing similar (but not exact) expansion rates.
 

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Hello TerryJ,

Can you tell me if the stud is a RH thread and also the nut dimensions. I'm planning to keep the Hyd unit but have the oil feed holes welded shut on my next rebuild.

BTW - xray, both the coil spring in the Hyd unit and the reaction spring tighten the belt. Take a look inside the Hyd unit cylinder with piston removed, and you'll see the oil gallery is at the bottom, so oil pressure forces piston up, de-tensioning the pully (thus it's name). Because of the offset pully axle, a lot of movement at the piston doesn't result in much at the pully. Pretty ingenious, but the design of the oil seal at the piston shaft, in fact having pressurized oil there is a recipe for leaks. This is why you'll see so many filthy 12 V6's (along with the cam hub seals leaking).Makes 'em stink too like burning oil in a frying pan!
 

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Discussion Starter #7
Toonrboy,

Its a standard thread Rightie Tightie/Lefty Loosey. I would just soak it with PB Blaster or something similiar for a few days and it should come out. Talking to Larry Sr. the other day he said alot of people just blocke off the oil feed and return and used the hydraulic unit a tensioner w/o the oil. Quess it would work just have to be tightened periodically. Terry
 
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