Megane engine destruction

READ THE MANUAL!
Then Fit a locating dowel through the block access plug hole into the notch in the crankshaft.
You can feel it going in.
Remove the plugs out of the back end of both camshafts .
Make up an aligning tool to line up the two camshaft end grooves.
FORGET ANYTHING TO DO WITH FUEGOS ETC!
Sorry, but we need to be blunt...
 
Belts rarely break, it’s usually operator error. Failed to replace all pullies and pump, didn’t follow the instructions, didn’t use new crank bolts, didn’t follow tightening procedures properly, didn’t change on time as well as kms.
 
The few I have changed were waaaaaaaaayyyyy overdue. The poogoe RCZ .... its bearing even all felt tight like freshly packed, brand new bearings at 180,000km and 12 years of age. The belt even looked perfect until you flexed it over and pinched it back against itself. At this point you could see fine cracking.

So I think the modern cambelts if well designed do last easily whatever the manufactures state..... and probably far, far longer if you have a very short change period. So if you follow the manufacturers directions and change all the tensioners and fit a new crank bolt (that has the lockign compound already coated on it) you should be fine ?
 
DoubleChevron said:
The few I have changed were waaaaaaaaayyyyy overdue. The poogoe RCZ .... its bearing even all felt tight like freshly packed, brand new bearings at 180,000km and 12 years of age. The belt even looked perfect until you flexed it over and pinched it back against itself. At this point you could see fine cracking.

So I think the modern cambelts if well designed do last easily whatever the manufactures state..... and probably far, far longer if you have a very short change period. So if you follow the manufacturers directions and change all the tensioners and fit a new crank bolt (that has the lockign compound already coated on it) you should be fine ?
Click to expand...
Again, you’re failing to appreciate the subtleties of anecdotes vs evidence…
 
Just a few comments on the modern procedures for fitting timing belts. From my readings. The cam timings in relation to the piston TDC are important to getting good pollution control figures. Due to manufacturing tolerances using marks and pointers etc is not so precise. So leaving out the keys and pinning the crank position and the cams direct is the most precise and easy to do at the factory, then just tighten all the pulley bolts. Probably the universal method now.

Pinning or marking the cam wheels does not work if they have no key to the cam. As in the Renaults and MANY other engines.
The same goes for pinning the crankshaft pulley, if it has no key (or a wide key way) or if the outer rim with the mark has slipped on the rubber harmonic balancer insert, which happens on some PSA engines and MANY other brands.

So while it seems like common sense to mark the pulleys and do things by first principles there may be hidden traps that are not revealed to you. You should not start the procedure without research and knowing EXACTLY what the correct procedure is. Then you might vary that a little if you have experience and possibly lack some special tools, but at your own peril. If you are not certain then do not do it !! Do not rely on the great old mechanic around the corner either.

The other point is the idler pulleys are usually plastic with bearing moulded in, and Renaults particularly, the plastic body can and does fail by cracking and I have seen pulleys replaced at the recommended belt change with cracks that were quite obvious. So buy the complete kit and do it properly and sleep at night. Get the supplier to do a VIN check to ensure you get the correct kit.
Just my advice Jaahn
PS the timing belts can last a long time(forever) if they are clean and oil free. The pulleys may not. If the seals are leaking oil that belt and the accessory belts may-will fail early. The accessory belt failing may get into the timing belt cover and cause it to fail too.
 
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and also the accesory belt ,i have seen a few scenics that had thrown the accesory belt smashing up the cam belt cover and droping bits of plastic onto the cam belt ,the one i baught as a fixer uper had all the valve heads floating around on top of the pistons like a rock crusher ,big dings in the top of pistons and head ,maybe was doing 100k on the freeway when it let go .a big mess ,if the belt starts to squeel fix it straight away !
 
Thankyou for all your advice. I find it strange that the crankshaft and the crankshaft gear have a slot for a key but none is fitted. The manual I have seems to show one in the diagrams. The crankshaft bolt was loose when I pulled the motor down so without a key the crankshaft gear has probably moved and caused the timing to be lost and so the valves have hit the pistons. There is damage to the top of the pistons but I don't think it is critical and so I am hoping that bent valves is the only significant damage. The head is off at a reconditioner so I will hear what the damage is soon. When I get it back is when the fun starts of putting it all back together and trying to get the timing right. I have replaced Fuego belts but they only have a single overhead cam. The biggest problem I had pulling down the Megane motor was the nut on the exhaust cam sprocket. It must have been at over 200Nm. How critical are new head bolts?
 
fregate said:
Thankyou for all your advice. I find it strange that the crankshaft and the crankshaft gear have a slot for a key but none is fitted. The manual I have seems to show one in the diagrams. The crankshaft bolt was loose when I pulled the motor down so without a key the crankshaft gear has probably moved and caused the timing to be lost and so the valves have hit the pistons. There is damage to the top of the pistons but I don't think it is critical and so I am hoping that bent valves is the only significant damage. The head is off at a reconditioner so I will hear what the damage is soon. When I get it back is when the fun starts of putting it all back together and trying to get the timing right. I have replaced Fuego belts but they only have a single overhead cam. The biggest problem I had pulling down the Megane motor was the nut on the exhaust cam sprocket. It must have been at over 200Nm. How critical are new head bolts?
Click to expand...
Have you acquired a workshop manual? Beyond my pay grade, but I have heard that sometimes these stretch bolts can be re-used, depending upon key measurements of their deformation, but why on earth would you NOT invest in new head bolts? Just saying... Bad luck about having to deal with this.
 
Do not reuse the head bolts for the same reason you do not reuse the crank bolt.They are not expensive. https://spareto.com/products/elring-bolt-kit-cylinder-head/258-180

You need the cam locking tools. No ifs or buts and no bodge workarounds. As has been said forget everything you think you know from a Fuego and read the book and use the right tools. This is nothing to do with single vs twin cams, it’s a whole another approach to setting timing.

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The camshaft nuts should be replaced as well, but I have re used that one before - but I’d only re use it once. This one is a genuine part only from a dealer but not expensive.

It’s not 200nm - it’s 60 (I think, something like that) and then 100 or something degrees. It’s in the book, but don’t just lean on it.

Sounds like you’re doing all this work because someone probably got lazy with the crank bolt and just hit it with a rattle gun, and/or re used a stretched softened bolt.
 
The problem is when it all goes bad it seems all the assembly is for an engine that IS Not at TDC.
 
New head bolts ordered, again thanks for the advice. The head, when it was stripped down, had 16 bent valves but no damage to the head itself. I think that I have on order, or already received, all the parts required to rebuild the motor. It will be a slow and careful rebuild and I have an e-manual that has lots of steps to follow and references to specialized tools that I don't have. How times have changed. I could get a Fregate R1101 head off in two hours and back on about the same time. Of course there were those wet liners and the inevitable leak of water from the water jacket into the sump on completion of the job.
 
I posted this a while ago. The official manual for the F4R timing. I hope it helps. Being a pdf file, Google can translate it for you.
 

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