24V Timing Tensioner

[SovraPressione]

Have a look at these 2 threads by our European counterparts on the new gen Timing Belt tensioner issues faced by the newer generation V6 24V.

Thread 1

Alfa Romeo forum: Another V6 rebuild ( GTA ) snapped belt
Lots of pics here. In this thread a 3.2V6 24V GTA snapped its belt after 3 years at around 50k miles. Reason of the snap; the belt was rubbing against the TB cover/housing DUE to a slight distortion detected in the body of the tensioner bearings after use. Arguably one might attribute this to one deaf owner who can't hear the screeching noise the belt was making rubbing against the housing on its way out.



Thread2:That's my cambelt gone.... - Alfa Romeo Forum

Various views on the recommended replacement period if one wants to be in the safe envelope.

However it is worth noting that the price of the new generation tensioners which is built together with the bearings as one unit is about half compared to the Tsubaki tensioners which need a separate tensioner bearing. So if Jason is able to somehow fit this 'new' tensioner to the 94-95 LS motors then it might be cheaper in the long run, but personally I prefer the Tsubakis due to its tough design and there has been no record (is there any?) of the distortion as mentioned above. But then again the new gen V6 24V oil pump is not driven by the cambelt so it is a totally different design and the Tsubaki tensioners might be considered as a luxury.... (by the FIAT accountants!!)

So the conclusion here is, we might want to support Jason to pursue the course of stocking up for the future of the manually adjustable Tsubaki tensioners for us. But since the issue of self adjustabilty for slack is highly desirable we might also want to see whether the new gen one might fit so that we can also have an alternative direct replacement, where the element of self adjustability of the tensioner is maintained. One more thing came to mind though, there is the added load of the cam belt driven oil pump on the 94-95 LS motor design that the new gen tensioners will have to contend with.

Attached are pics posted somewhere in this forum before. Note the similarity of the Ferrari's timing belt tensioner (two separate Tsubaki type tensioners!) to that of the 94-95 LS V624V design in relation to the newer generation V6 24V reverting back to the older 12V version.

[richardbradford]

Quote:

Originally Posted by Alfissimo Int. I am ordering in some newer detensioners as I am certain these are going to be the replacement for the older style. I will have info on adjustment as soon as I can. I will confirm with alfa someday soon. This will be a less expensive repair if bearing and tensioner are going. Instead of $290 for the tensioner, $151 for the bearing, the price for the new style is around $125.00 Procedure: Changing a cam belt is one of the most difficult service jobs on an Alfa Romeo and should only be attempted by a skilled motor mechanic with the correct tools. As such, this is just an overview so you know what is being done to your car. Alfa Romeo V6 24 valve Engine The first thing to do is to remove the right hand front wheel and under tray and right hand side engine bay cover, making sure the car is lifted in a safe manner and supported on axle stands. Plenum removed Then you have to remove the plenum chamber this is only secured by two allen keys hidden down behind it and once these are removed you have to disconnect all the pipes and wires from it, including the chrome inlet tubes, and then the engine breather pipe has to be removed from the rocker cover as you can’t pull the plenum back with it in place; now the plenum will pull off, on some models you will have to disconnect the engine management unit Alfa Romeo V6 engine rear coil packs Once you have removed the plenum chamber you can then remove the rear coil packs, these are secured by four 10mm nuts. when refitting the plenum make sure that you don't trap any of the wires to the coil packs and be sure that you are happy with the spark plugs and coil caps as they are difficult to get back to if there is a problem when the car starts up again. It is probably best to remove the front cam cover next and then remove the front coil packs and get them out of the way by laying them over to the left of the engine bay. Cam locking tool on inlet camshaft Now both rocker covers have to come off, this entails loosening three of the chrome inlet tubes in order to get at the securing 6mm allen keys on the rear cylinder head and be careful with the dip stick securing bracket on the front head once this is off the engine needs to be turned over until the cam locking tools fit and these should now go on their respective camshafts. DTI down number 1 cylinder Number one plug can now be removed and the DTI can be fitted in its place. Cam belt cover removed Now we have to remove the auxiliary belt and both its tensioner and idler and it is also best to remove the lower crankshaft pulley at this point. Next remove the covers from the cam belt, the upper cover is secured by three fasteners and then it pulls vertically upwards to remove. Cam covers removed Remove the auxiliary drive pulley and then both the lower covers are accessible these are secured by three 5mm allen keys and these are a bit tricky to get to and will include much skinning of knuckles. The cam belt is now accessible and can be removed by loosening its tensioner. Before refitting it is worth considering fitting a water pump especially on the 2.5 V6 as the plastic impeller cracks and causes problems with engine cooling. It is always necessary to replace the tensioner as they wear out and if they break they will destroy your engine. In order to refit the cam belt it is necessary to loosen all the cam drive pulleys as they need to rotate to get the correct tension on the belt, once they are loose, tension the belt and then do up the pulley securing bolts. From here on it is only a case of reversing the above procedure. More later j

[Alfisto Steve]

You can slip belt off crank pulley sideways without pulling pulley.

AS for painted/etched marks on cam pulleys they are only as good as last person doing the work. If car runs/ran good with marks lined up fine.

Be advised you have to try and get new belt on crank cog, cam pulleys and aux pulley and hope you can keep marks lined up. It is a challenge to get all 6 cog pulleys under the belt and keep the cams in time if you don't remove valve covers and lock cams with either timing dies or wrenches on cam flats while you set tensioner air gap and belt tension.

Not trying to scare you but short cutting the operation can be trying on an Alfisti's soul to fine tune belt tensioning and cam timing.

[richardbradford]

Quote:

Originally Posted by Alfisto Steve You can slip belt off crank pulley sideways without pulling pulley. AS for painted/etched marks on cam pulleys they are only as good as last person doing the work. If car runs/ran good with marks lined up fine. Be advised you have to try and get new belt on crank cog, cam pulleys and aux pulley and hope you can keep marks lined up. It is a challenge to get all 6 cog pulleys under the belt and keep the cams in time if you don't remove valve covers and lock cams with either timing dies or wrenches on cam flats while you set tensioner air gap and belt tension. Not trying to scare you but short cutting the operation can be trying on an Alfisti's soul to fine tune belt tensioning and cam timing.

[Alfisto Steve]

Those machined lines may have been done after belt set and pulleys tight on tapered cams (24v cams and pulleys do not not have keys just a tapered fit).

I have found it works well to have cams locked down with timing dies and then knock loose at least one pulley to help install belt and set tension then once tension set torque down cam pulley(s) before you remove timing dies and you have a perfect timed engine providing you have a perfect Top dead center setting on crankshaft. I use dial indicator in number one cylinder as well as timing mark on crank pulley.

Maybe I am just a little anal on setting up cam timing.

[richardbradford]

Quote:

Originally Posted by Alfisto Steve Those machined lines may have been done after belt set and pulleys tight on tapered cams (24v cams and pulleys do not not have keys just a tapered fit). I have found it works well to have cams locked down with timing dies and then knock loose at least one pulley to help install belt and set tension then once tension set torque down cam pulley(s) before you remove timing dies and you have a perfect timed engine providing you have a perfect Top dead center setting on crankshaft. I use dial indicator in number one cylinder as well as timing mark on crank pulley. Maybe I am just a little anal on setting up cam timing.

[velocedoc]

What about getting the tensioners rebuilt on an exchange basis?

[velocedoc]

Some motorcycles use belts with tensioners. Maybe something off of an Italian bike might be adapted? Just suggesting.