We have a 2008 2 litre Megane and a newly fitted cam belt has jumped a few cogs causing internal destruction. Has anyone had a similar experience with valves hitting pistons, as tends to occur with interference engines when this happens? Is it usually terminal for the engine or is there still hope? I realize that the head will have to come off to see the extent of the damage and valves will probably be bent. The engine did still turn over after the episode but she would not start. There did not seem to be any mechanical interference. If it is terminal for that engine we may have access to an engine from a similar Megane but it is an auto. Is the crankshaft the same for the manual and the auto?
Megane engine destruction
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The valves will mostly be bent, sometimes some of the bottom of the valve guides are broken also. Often with the Megane engine this happens when the crank pully is not tightened sufficiently to clamp the cambelt pulley in place as there is no keyway, or maybe not timed correctly in the first place. Petrol Megane?
Not the same engine but my stepson's Clio 1.4L 16 valve unusually had one cam come loose 60 000Lkm and a few years after the belt was done by the dealer. Many valves were bent but there was no real damage to the pistons, just some marks in the carbon. I bought a complete second hand head for $300, gave it a clean and a check and fitted it about 50 000Klm ago. Motor is still running fine not using oil at 210000 and has had a hard life.
Not the same engine but my stepson's Clio 1.4L 16 valve unusually had one cam come loose 60 000Lkm and a few years after the belt was done by the dealer. Many valves were bent but there was no real damage to the pistons, just some marks in the carbon. I bought a complete second hand head for $300, gave it a clean and a check and fitted it about 50 000Klm ago. Motor is still running fine not using oil at 210000 and has had a hard life.
It is unlikely to be terminal as the valve stems are quite skinny and while there will be witness marks on pistons replacing the bent valves should fix it.
I have don’t this on an engine where a failed tensioner allowed the exhaust cam to slip some teeth and bend all 8 exhaust valves.
Pull the head off and inspect. Valves are pretty cheap, although you may as well do it properly and have the head reconditioned and valves properly reset in the head and new guide seals fitted. And of course have the head skimmed.
If you are really unlucky, an auto engine is the same as a manual one - the crank is the same. Only thing to watch is the auto was not obviously fitted with a pilot bearing, so it might have rusted where the bearing fits and it might not be tight fit anymore. Sleeves can be fitted if you’re this unlucky.
I should just point out. The procedure for fitting the toothed cam belt is spelled out in detail in the book and videos. BUT you do need to do it correctly or !@#$%^&*.
If you cannot read and follow the instruction exactly on all new engines then do not start the job. The old ways of doing these things does not apply and all new engines are interference types and usually do not have keys or easy markings.
Jaahn
If you cannot read and follow the instruction exactly on all new engines then do not start the job. The old ways of doing these things does not apply and all new engines are interference types and usually do not have keys or easy markings.
Jaahn
Hi there, just comment on engine compatibility, and I am totally ignorant of RENAULT stuff (except PRV V6's).
There are two quite different bolt patterns for the RHR 16 v 2L diesels in Citroens and Peugeots : 4sp auto (407) and 6sp auto different. I suspect the manual versions stuck with the early pattern for a while . . .
And years ago in another life there was a Camira I was given, and it turned out the auto and manual had different blocks. This reduced the value of the car considerably such that I paid to have it taken away. Jon
There are two quite different bolt patterns for the RHR 16 v 2L diesels in Citroens and Peugeots : 4sp auto (407) and 6sp auto different. I suspect the manual versions stuck with the early pattern for a while . . .
And years ago in another life there was a Camira I was given, and it turned out the auto and manual had different blocks. This reduced the value of the car considerably such that I paid to have it taken away. Jon
No such issues with the F4R block or its crankshaft.
I wonder whether the pulleys were changed as well as the belt. A full kit is more expensive but the way to go.
if you follow the manuals directions for cambelt change ... and also mark the old belt before removal ... and duplicate the marks to the new belt, how can you possibly get it wrong 
Those old techniques are irrelevant to these engines.and also mark the old belt before removal ... and duplicate the marks to the new belt, how can you possibly get it wrong
Don't forget - there's no 'key' to ensure the pulley retains it's original position on the crankshaft...if you follow the manuals directions for cambelt change ... and also mark the old belt before removal ... and duplicate the marks to the new belt, how can you possibly get it wrong
Is there no way of marking the pulleys and belts with a line so it can all be lined up (ie: draw a line across the belt and pulley and across the block/head so it goes back together in exactly the same place. What is the idea behind no keyway? that sounds crazy!
Many have come to grief assuming cambelt marking works.
Crankshaft, both cams etc. have to be locked in their correct position
before removing the old belt, fitting the new one and adjusting tensioner.
Crankshaft, both cams etc. have to be locked in their correct position
before removing the old belt, fitting the new one and adjusting tensioner.
I mark the belt just to double check everything .... even though I do use every timing pin required .... I have not changed a megane timing belt though, so have no idea of the complexities involved.
Out of interest, how tight is that crank bolt. I was amazing at the force required to loosen the crank bolt on my wifes poogoe. I coulnd't budge it, even with big breakers bars! (loctite and TIGHT!)
Its all done this way so that it is easy for the guys & gals on the assembly line. Just put the pulleys on then the belt, tension the belt and do every thing up to the required torque.
The people that need to do the belt changes 4 years or 100,00 Km down the track are not really given a thought to.
I have only done poogoes and citroens ... but usualy I just pin the cam(s), crank (usually at the flywheel). after strugling to identify the holes to pin it from .... usually I pin them ... then struggle for bloody ages to get the belt on. Then struggle to get the damn tensioner in places and tensioned (they are all positioned so you can't access them).
But so far it has always worked out for me
I always mark the belts and pulleys as a verification though ... and transfer the marks from the old belt to the new one. I reckon I would have got it one tooth out a couple of times without the extra markings 
I have changed my Laguna V6 (same engine as the ES9L4S) a couple of times. These have pins that lock up the cams and crank. All pretty easy if you follow the instructions exactly.I have only done poogoes and citroens ... but usualy I just pin the cam(s), crank (usually at the flywheel). after strugling to identify the holes to pin it from .... usually I pin them ... then struggle for bloody ages to get the belt on. Then struggle to get the damn tensioner in places and tensioned (they are all positioned so you can't access them).
But so far it has always worked out for me
Interestingly I marked everything on the Fuego J6R engine and discovered by reading the R18 manual there was access on the side of the block to put a locking pin that was exactly the right fit for an old nail that was used to hold guttering back in the day. This locked the crankshaft but not the cam so marks were essential as well. But I was also very careful not to move the cam. I did have the radiator and air conditioning out so could clearly see the front of the engine. I'd hate to do it with them still in place.
says the cam belt has jumped a few cogs so there is no point marking anything i would have thaught ,only to ascertain were it shouldnt be or posibly a few notches back but how many ?