V6 Engine Cambelt change

[chrisp]

I've just bought a Gates kit to replace the cambelt, tensioner pulley and idler pulleys on my V6 engine. On looking at the kit 2 questions have arisen which I hope someone can help me with.
1. The bracket with the tensioner and upper idler pulleysin the kit is the later post-1997 version with flanges on both sides of the tensioner pulley. My 1993 V6 has the earlier design with the outside of the tensioner pulley flangeless. The bracket itself looks identical to the earlier design. Also, I've looked at Gates's website and they offer the same kit part number for both pre and post 1997 V6 engines.
So can I safely use the new bracket and pulleys on my 1993 V6? I'm inclined to think so, but am not completely confident about it.
2. The new cambelt has markings on it to line up during installation with the timing marks on the crankshaft sprocket and the 4 camshaft sprockets. I expected to see these. However, what I did not expect was to see two separate sets of markings - one set in white and the other in beige, separated by a few inches along the belt. I've no idea why there are two sets, and the Gates installation instructions do not refer to them at all. I've emailed Gates's support system asking about this but, so far, have not received a reply.
Can anyone help to explain the use of these?

[chrisp]

I emailed Gates for more information on the different markings on their cambelt but, disappointingly, I have received no reply from them.
So I've done some more researching online and turned up a US YouTube video showing the fitment of a cambelt to the same V6 engine that is used there in the Cadillac CTS (which is really a Vauxhall Omega in disguise). http://www.youtube.com/watch?v=DFWtovLxE4Y
This indicates that the white markings are used on the pre-1997 (1999 in the US) engines with the flangeless tensioner pulley where the cambelt can be fitted in an anticlockwise direction. The beige (or yellow as they're called) markings are used in the later engines with the flanged tensioner pulley where the cambelt has to be fitted in a clockwise direction. The beige markings are for the crankshaft and for cam sprockets 1 & 2 (rear of the engine for Calibras and Cavaliers). The white markings are for cam sprockets 3 & 4 irrespective of the year of the engine.
I then compared the tensioner bracket casting on my 1993 engine with the new one supplied in the Gates kit - and they are not identical. The tensioner pulley in the Gates kit is mounted further "out" than in my older version. I think this explains the need to use the beige markings - because the cambelt has further to 'travel' between crankshaft and tensioner pulley as you fit it. This also applies to cam sprockets 1 & 2 of course, but not to sprockets 3 & 4 because the idler pulley between the two sets of camshafts can be adjusted accordingly.
This still doesn't explain whether you can fit the later bracket, flanged tensioner pulley and idler pulley to the earlier engines. The fact that the Gates kit part number is apparently the same for all V6 engines would suggest that you can, but I am still cautious about this. I think I'll swap the idler pulley from the new bracket to my older one, and leave the flangeless tensioner pulley in place, Luckily, the bearing on this still feels smooth in operation.
It really would have been helpful if the Gates kit had this information packed with it - or online - but unfortunately it does not, the online instructions are very generic.

[Robsey]

Sorry Chris,
I have never worked on, or owned a V6 Cavalier.

Hopefully James or Andrei will be able to cast some light on your query.

[chrisp]

No problem Robsey. I've almost solved my own problem so though I'd post it here for information as much as anything else

[chrisp]

Gates, who supplied the kit K015453XS for replacement of the timing belt and pulleys on my 1993 Cavalier V6 have, despite my initial pessimism, been very helpful in sorting out the use of the white and yellow timing marks on the belt and the issue of flangeless and flanged tensioner pulleys.
The changeover from a tensioner pulley with no front flange to one with flanges at both front and back occurred in 1997, so my 1993 V6 engine came with the flangeless pulley. Gates has confirmed that the flanged tensioner pulley, together with its mounting backplate and top idler pulley, as supplied in their kit, is a direct replacement for my flangeless version, and that this change has nothing to do with the use of the white or yellow timing marks on the belt. Since the flangeless pulley has been associated with the belt riding forward and scuffing the plastic cover, changing over to the flanged design is a good move (though I’ve never had a problem with my flangeless design in 114,000 miles).
The white and yellow timing marks relate to a later change which occurred in 1999 and is illustrated in the diagram. The left hand diagram shows the pre 1999 arrangement, while the right hand diagram shows the post 1999 arrangement. The only difference is that the idler pulley up from the crankshaft in an anti-clockwise direction in the diagram has been moved higher up. For the pre 1999 engines, solely the white timing markings on the belt are used. For post 1999 engines the yellow marks are used for the crankshaft and cam sprockets 1 & 2 (the pair on the left in the diagram), while the white marks are used for cam sprockets 3 & 4 (the pair on the right in the diagram), there being no yellow marks for these two positions.
So, with Cavalier Mk3 manufacture ending in 1995, and Calibra manufacture ending in 1997, the yellow timing marks only apply to later Omegas – and of course subsequent Vectras and other GM cars that used the V6 engine.
This has taken significant effort to sort out – I wish the timing belt kits would come with a simple printed sheet with this explanation and diagram.
And yes, I know that people have successfully changed timing belts without using the timing marks on the belt. I have done this several times also, and without a locking tool kit either, but now I have a locking kit I want to do the job “by the book”.

[chrisp]

Addendum: I’ve just been able to look at the excellent DVD from the Omega Owners Forum showing V6 timing belt replacement. This states that the different backplates for the tensioner and upper idler pulleys are NOT interchangeable. This is in opposition to Gates’s advice that the later backplate is a direct replacement for the earlier one and, having taken another look at my original backplate and the new one in the Gates kit, I can see that they do differ significantly in the position of the tensioner pulley. So I think the best advice is, if the kit supplies a different backplate to the one on your vehicle, just swap the older tensioner and upper idler pulleys for the new ones in the kit and keep the original backplate. It appears that you can still swap a flangeless tensioner for the newer flanged type when doing this. The advice on which colour timing marks to use is unaffected by this new information. Ho hum – why is this so complicated?

[chrisp]

New information that I have just received via the Omega Owners Forum is that the Gates advice is correct and the new design backplate, tensioner pulley and upper idler pulley assembly in their kit is indeed a bolt-on replacement for the older design in my engine. In fact it is NOT recommended that I move the newer tensioner and upper idler pulley from the new backplate to my older one. So.....you pay your money and take your choice!

[Robsey]

Blimey!! How confusing!!

Always seems to be the way with anything to do with Vauxhall / Opel.
They do not seem to do anything in a straight-forward manner.

[cavalier1990]

Jeez what a pulava, I'm currently doing my Omega belt change with a Gates kit, luckily it's nowhere near that changeover period but I'll keep an eye on those bits anyway ....just...in...case! good info there all the same though, good shout Chris !

[vexorg]

I've done quite a few v6 cambelts, I thought it was only the later engines, 2.6 and 3.2, that had the different backplates.

[chrisp]

Yes, I also thought that it was only the later engines that had the revised backplates - which also have a fully flanged adjuster pulley, instead of the older flangeless-on-the-outside one. However, after protracted correspondence with Gates, they insist that the revised backplate and fully flanged adjuster pulley supplied in their kit is a proper replacement for the earlier backplate. I've not yet tackled the cambelt replacement on my Cavalier V6 (too cold & wet!) and I'm still not sure whether to swap the new pulleys over onto the old backplate or go with Gates's advice and swap over the whole backplate assembly.
Whatever, I did at least establish that the difference between the white and yellow installation markers on the cambelt is nothing to do with the older or newer backplate (as I initially thought) but relates instead to the position of the idler pulley that is located in a lower or higher position up from the crankshaft in an anticlockwise direction - as shown in the sketch that Gates sent me and which is included earlier in this thread. It's a pity that Gates does not include this information with their cambelt kits.
If there is anyone with experience of the older flangeless adjuster pulley and whether it can be replaced with the fully flanged one and accompanying newer backplate then I'd be pleased to see their comments. I've raised this issue on the Omega and Calibra owner sites, as well as this one, but no-one was able to put me right. It looks as though I may be the only person left with a V6 engine with the earlier backplate!
All that said, I've done 114,000 odd miles with this older cambelt arrangement without trouble - and renewed just the cambelt on at least 2 occasions during that time, so the design can't be too bad.

[vexorg]

I dont believe any stock calibra would have the later config. Even the later engines with the X25 blocks had the same cambelt arrangement. And they weren't interchangeable as a full assembly, the old pulley pair did not fit on the 3.2 engine. And the 3.0 was the same as the older 2.5

Cant say I ever bothered with the belt markers, as long as the pulleys lined up then I was happy.

[cavalier1990]

With the kit i got recently for my omega 2.6, the backplate was different for the one I had on it originally, which says 6B on it, but the one in the gates kit says EB I think. But from what I am gathering, the gates kit (the cheaper one) for the 2.5 had a revised backplate that can be used on the early or later 2.5 cavaliers, imaging that includes the 2.5 omegas, with an omega 2.6/3.2 you have to use the old backplate but with the new rollers, and the belt will fit. With the gates belt though it will have yellow double line mark and a white double line next to it for the crank line up. From info I gleaned on this, I used the yellow mark on the crank, and this then meant you line up the yellow marks on the belt for the left bank of cams, and the white marks for the right bank of cams. With GM kit it's white marks only, there is no yellow marks.

I've got to hand it to GM/Gates they've taken a pretty straightforward process and threw it in a blender!