Technical advice please on v6 cambelt job .

[chris75]

I'm gathering parts ready for doing this job . I also have the Sealey locking tools so envisage going the approved route using them. My queries relate to the camshaft sprockets on the front end ;
1. If i undo the sprocket bolts , the advice is not to reuse them . Do people reuse them , or are they really stretched after one use ? I ordered what I thought was a set of 4 ( for the back end ) at just below £4 , and in fact it turned out to be £4 just for one That will be nearly £24 for all 6 bolts needed . They are not even gold plated !
2. I am still a little puzzled by the fixing arrangement on the front sprockets . I understand that they are not locked to the camshaft , and allow a little rotation to perfectly tension the belt . This being so , how can the locking tool accurately locate the camshaft , unless the separate sprocket hubs do locate in the end of the shaft and the sproket can move on the hub? Is this the case ?
3. At the moment I am contemplating using the locking tools without unbolting the sprockets (at the front end ) and reusing the bolts at the rear sprockets. I would value informed comment on this from those who know , so I am better prepared for the job .
I have studied all the posts I can find on this , but haven't found answers to these questions , but I bet someone out there will know

[T-Cut]

You should watch this video: http://www.youtube.com/watch?v=2fFx8SPiTSc

[chris75]

[QUOTE=T-Cut;306626]You should watch this video: http://www.youtube.com/watch?v=2fFx8SPiTSc

Thanks T-Cut . I appreciate that the official view is to fit new bolts , but having over the years rebuilt various engines and reused the old bolts I am just asking for peoples thoughts on common practice . I suspect that many lower price belt jobs done on these engines does not include £24 for new bolts, even though this is not great in comparison to the whole job ? Why are they so dear ; perhaps they can be obtained cheaper if they are not in a Rover bag ? The markings on the head are M AA 10.9 if anyone is a bolt expert !

[Kandyman]

Not a bolt expert but for the sake of £24 i would fit new ones.

if no members come up with any help maybe drop Lates a PM/Call i am sure he would offer his advice if a beer was on the offer

Good luck

[workaholic_ro]

Originally Posted by chris75

I'm gathering parts ready for doing this job . I also have the Sealey locking tools so envisage going the approved route using them. My queries relate to the camshaft sprockets on the front end ;
1. If i undo the sprocket bolts , the advice is not to reuse them . Do people reuse them , or are they really stretched after one use ? I ordered what I thought was a set of 4 ( for the back end ) at just below £4 , and in fact it turned out to be £4 just for one That will be nearly £24 for all 6 bolts needed . They are not even gold plated !

Seems that they are gold made and blacken to hide this! Judging by their size and the tightening torque I think that they can only be used a hundred times and no more I didn't change mine.

2. I am still a little puzzled by the fixing arrangement on the front sprockets . I understand that they are not locked to the camshaft , and allow a little rotation to perfectly tension the belt . This being so , how can the locking tool accurately locate the camshaft , unless the separate sprocket hubs do locate in the end of the shaft and the sproket can move on the hub? Is this the case ?

The hub is locked to the camshafts and obviously to the rear sprockets which are keyed. When using the front setting tool you'll notice that the rear pulleys are aligned. Having the engine aligned and also the camshafts, the "free" front pulleys allow an even tension distribution along the belt. They lock when tightening them. And here is a recommendation that puzzled me a bit: "25Nm and 90 degrees further". Not very sure about this but I think that they are cone mounted, that 25Nm is the value which guarantees that the cone is sitting in the right position and 90 degrees more gives the right expansion of the cone to have enough friction for keeping the pulleys locked. This would justify somehow the recommendation for using new bolts, for the sake of precision and not because they are worn.

3. At the moment I am contemplating using the locking tools without unbolting the sprockets (at the front end ) and reusing the bolts at the rear sprockets. I would value informed comment on this from those who know , so I am better prepared for the job .
I have studied all the posts I can find on this , but haven't found answers to these questions , but I bet someone out there will know

Actually there is no need for a front setting tool, an ordinary ruler will tell when the camshafts are aligned, I used a home made tool (a long one) to keep them in position while tightening the bolts, without removing the rubber caps.
There are two possible approaches to this operation: "use a tool kit and follow the instructions" or "understand how it works and take it on your own". In lack of a kit I had no choice. I think that combining them would be best.

Edit: forgot to say "GOOD LUCK!", and I think we should open a club I wonder, how many members had done it by themselves. (professional mechanics don't count of course)

Two pics to give you strength and confidence

[T-Cut]

I think this type of bolt is expensive because of the way they're tempered after manufacture. They are designed to stretch till they reach the correct torque at which point they aren't redo-able. I guess the structure of the steel changes at the elastic limit.
Having said that, I'm pretty sure that not all such bolts (there are lots around the car) are renewed, even by the MGR depots (as was). However, I bet most places renew the head bolts for example. Why should the camshaft sprocket bolts be regarded different? I dunno? The front seat anchor bolts for example were not replaced at my local Rover dealer 'cos I asked them, even tho' the manual says they should. Whether ones on the engine are regarded different I can't say. I guess you have to take an informed decision as to the risk. It's a big expensive job anyway.

[newcybrown]

The rear bolts must be replaced or you will not be able to torque the old bolts back to the required torque and for the sake of an extra £16 do you want to take that risk.

The front sprockets are not "keyed" to the camshaft if you have to undo these bolts same thing you will not be able to tighten them to the correct torque.

The only reason to undo the front sprockets is to align the new belt, if it won't quite go over the sprocket you loosen the bolt chuck it away rotate the sprocket and tighten with a new bolt once you are happy with the location of the new belt.

You must not rotate the camshaft as that can cause damage to the 2 camshafts on each bank and you will lose the timing and it would be a hard job to locate again.

I will be looking to do this job and i don't see why the front sprocket bolts need to be loosened.

I have thought about fitting the locking tools to both of the rear sprockets, once the engine is in the correct timing position and the crank lock pin inserted, then will look at removing the front belt as the crankshaft and camshaft's will be locked and they will not move.

Then you can remove the old front belt and refit the new one hopefully without un-doing the sprocket bolts.

Once the front belt is changed i will fit the front locking tools to prevent rotation of the camshafts then will be able replace both rear belts.

My bro' in law used to work for MGR and did this job many times after i told him about the above he can't see any reason why un-doing the front sprocket's would be necessary obviously he would do it the way MGR taught him to do it.

But until i commence the job I'm not sure if all the above is possible.

[EXMSRalph]

Originally Posted by workaholic_ro

Seems that they are gold made and blacken to hide this!

The Maltese Falcon

TBH I don't think that we replace these bolts when we do a cam belt change - I've certainly never charged a customer for them. Then again, I may be losing out here by not charging for something that we do fit...

Don't forget that you need to replace the camshaft end caps (LUC100150) as well.

[workaholic_ro]

Originally Posted by chris75

You must not rotate the camshaft as that can cause damage to the 2 camshafts on each bank and you will lose the timing and it would be a hard job to locate again.

Sorry to disagree but it's piece of cake. The only thing you are NOT allowed to is rotate the engine. It must be kept in the locking position until the job is done. The rear pulleys have marks and are easy to align as many times you want. The picture above is NOT the correct setting position, the camshafts are rotated by 180 degrees.

[workaholic_ro]

Originally Posted by EXMSRalph

Don't forget that you need to replace the camshaft end caps (LUC100150) as well.

...but only if you had removed them; I didn't