Megane cambelt change

Cambelts are often very simple to change but it's worth getting a Haynes BOL if you haven't already got one - just in case you need special tools etc.

Si

I've got the Haynes manual, but haven't read through the cambelt change section as it looked rather long with lots of cross references to other sections like they do. It is very difficult to tell just how hard a job is from Haynes. "Remove bolt" can often require an infinitely small spanner, arm, and more torque than a steam roller. Whereas "refer to section 4 to remove whole engine" might just really need to bend back some plastic panel.

You speak the truth, which is more than Haynes do. Tried an independant garage? Mine always gives solid quotes and they're a lot cheaper than a main dealer.

Si

Replying to my own question, going mad...

I think the key with the cambelt is getting the tension correct, and the Haynes manual recommends using a "SEEM C.Tronic" tension sensor thing - whatever one of those looks like. I'm assuming these are as rare and expensive as golden dodo eggs.

Would the approach of slicing the old cambelt along its length, removing the outer half; then sliding on the new cambelt; before cutting off the remaing half of the old one, be effective? I'm hoping this technique would ensure the tensioners stay in position, and are at the correct tension, so the new belt will automatically be correctly tensioned?

Has anyone ever tried this technique?

The message from dave snipped-for-privacy@mailandnews.com (Davemar) contains these words:

That assumes that the old belt hasn't stretched or that the new one has.

I'd suggest that manufacturing tolerances would mean that the tension has to be set each time.

But the tensioners would still be in the position they were when the belt was tensioned originally. So if new belt is identical to the old belt was originally then it should end up the same. Assuming the tensioners haven't nudged over time.

That's a good point, I wonder just how much effect that has, and how much tolerance there is on belts.

0.5mm/m for industrial ones, they also expand quite obviously with temperature (getting tension on a 30m long 2" diameter one can be intersting :-)

better to change it at the same time as the belt because as you are gaugeing the tension it may 'groan' when you fit a new belt.

the crank (19mm I think) and expose the drive for the belt you should see a dot on that as well.

fitment.

crank drive dot.

be helpful to mark outside edge of belt with white marker)

mark on belt lines up with crank dot(you can keep it in place here by jamming a a bit of rag or something between the belt and casing "recommended")

around a small "dimple" and can move when you are fitting it)

you have used to secure belt.

STARTER!!!!! Put it in top gear,and turn it through a couple of wheelbolts and a lever (one wheel on the ground)

is nothing better than experience as a teacher here. Regarding the 'SEEM' tensioner,they are impractical and impossible to use due to the restricted space. The only time I've seen them used was on training courses when the engine was on a bench.

straining your tensioner or worse your water pump.

whine when you start it up. Too loose, the belt will flap. OK in the workshop but on driving in overrun it will jump causing valve damage.

CRANK!!!

Good Luck. KG