Camshaft bolt reuse
 

What is the general opinion of re-using the bolts that secure the chainwheels to the camshafts? (K & KV6 engines).
Officially they are to be replaced with new when disturbed, but I'd like some reasoning on this.
Usually I would probably replace but am in a situation where I am one bolt short. Reason can be seen in my post in 'my KV6 cambelt change' where I have also raised this question.

Had loads of them in and out and wouldn't hesitate to do the same on any of my cars. Probably more of a warranty thing

If it looks good condition wise then throw it back in. Drive shaft nuts also fall into this category and of all the wheel bearings I've changed and all the drive shafts I've had off I haven't replaced any that are damaged

Completely different reasons for not re-using driveshaft nuts though, and it is because they are staked. Stake them too many times in the same place and the staking is less secure. Of course if you swap them over with the other side chances are you will find a fresh part of the rim to stake.

The camshaft bolts are angle tightened so are yielding when used. Probably enough safety margin in them to cope with being re-used, but of course you don't know how many people before you have thought the same.:getmecoat:

I have no problem re-using drive shaft nuts, but I'd use new camshaft bolts just for the peace of mind.

Each to their own though. :}

I suspected that they were being tightened into the plastic deformation range which is why I was also concerned over turning the extra 90 degrees in more than one movement. I did get extra bolts so I will use a new one should I find it necessary to alter one camshaft, and keep the 'tightened once' bolt for possible use on one of the secondary wheels next time I do the job.

It occurs to me that in time these bolts will become no longer available then how do we go on? Certainly not a good idea to use them more than twice.

Any Patchlok bolt the manual says discard and replace as standard practice (are the cam ones that type?). It's easy enough to clean the old thread lock off and re-use with fresh.

The 8mm cam bolts are 45Nm(?) which is fairly tight for the bolt spec i.e. getting towards the upper end of the elastic deformation. I've reused them many times with no issues but always use a torque wrench when tightening.

The 10mm ones are well within their limits.

These bolts are far from plastic deformation.
They operate well in the elastic range, which means they will revert to original size when released.
There has been numerous discussions from all walks of life, especially on the stretch bolts for the 1.8.
I have found and referred to an article by the company that designed the bolts for the 1.8, and the head man there said that they can be re-used a number of times.

http://www.boltscience.com/pages/glo...ingarticle.htm

I think you should ask if ANYONE has had any problems re-using these bolts. I have re-used them, with no problems. As a matter of fact, I have never had a problem with any critical bolts on any engine I have built. I have some threads come out of aluminium blocks on Rovers, but I suspect our hamfisted "technicians" in this country have got a fairly flexible view to applied torque, so the damage was most likely done before I arrived on the scene!!:D

In some cases "re-use" by Rover is synonymous with "we have used some compound on the bolt, but we don't want to tell you" thus "buy new".
Does not make a lot of sense to a private chap trying to keep his vehicle on the road, does it?

Do any of these bolts come with locking compound on them ???

If so then the second time they are used they would no longer have any compound on them.

Perhaps a new coat of Lock-Tight is all they would require.---:shrug:

Ok, maybe better comparing it to a head bolt. So long as it's undamaged etc etc then no issue reusing it.

Good comment on the thread lock though, definitely reapply some. And Idealy the strong stuff if you can get it, but any is better than none

THanks Kaiser for posting the bolt information.

Threadlock not specified for use on the camshaft bolts so didn't apply it (I was using new bolts anyway). I have used locktite 242 elsewhere where specified.

As to bolts tightetening torque being a bit high, I did have concerns over the 85Nm for the five bolts on the engine front plate, seemed to be turning a long way before the torque wrench snapped. If I have to do the job again I think I'll use locktite and reduce the torque setting.

Re-using bolts that have been torqued to yield, will in most cases work. That is clearly explained in the link above.

But comparing the cost of the bolts against the cost/time of the job done, the outcome of a potential failure and the piece of mind, its not worth skipping a efw new bolts. Its up to each own to decide...