HELP! 172 Cambelt -jumped a tooth?????

[Nicolasticity]

172, year 2001, noise from cambelt end - probably a tensioner, cambelt OK but engine wont start. Diagnostic is the belt has slipped possibly due to the tensioner failing or getting loose (was changed at 35K by a main dealer - car now at 66K mls)

So was going to check out and change the belt - realise its a big job and also the crank pulley is not splined. (if I can prove its slipped I wont need to remove these pulleys??)

Would the valves have had it if it slipped say one tooth? Was going to build and start it up and see if it was OK?

Anyone got a data sheet on the job as I cant seem to find a manual for the engine? Let me know.

Any help and advice welcomed.

 

[Nicolasticity]

Im going to remove the cambelt cover and have a look - high costs of getting the work done (£4500 to fix a snapped belt!) plus the fact that I used to work as a fitter has prompted this decison -I will post pics along the way and let the community know how easy or difficult the job turns out.

Any help appreciated

 

[realnumber 1]

£4500?:S ?
From what I've read on here your only looking at around £1500 to replace the engine. If your doing half the work yourself then might be able to fix it for less.

 

[maz172cup]

Can buy another RS for £4500....£1500 sounds about right

 

[bmh.01]

One tooth shouldn't be enough to kill valves I don't think as a few people who've taken them to garages that haven't used the locking tools have had them back a few teeth out and the car still ran just with very reduced performance.

On that point you want the locking tools before you take the belt off or start unbolts pulleys and tensioners etc.

These: http://www.lasertools.co.uk/item.aspx?item=747&cat=309
and this for the aux belt tensioner: http://www.lasertools.co.uk/item.aspx?item=1155&cat=309

Plus theres another one you need if your undoing the cam pulley bolts. Like this: http://www.lasertools.co.uk/item.aspx?item=911&cat=309 although I think that is just for the 1.4/1.6 although the tool looks the same.

 

[Nicolasticity]

£4500?:S ?

http://www.cliosport.net/forum/showthread.php?t=354553&page=3&highlight=snapped

this is where the £4600 'estimate' was found.

Thanks for the tool advice - how does the tensioner work - do you need a spring gauge?

 

[realnumber 1]

£4500?:S ?

http://www.cliosport.net/forum/showthread.php?t=354553&page=3&highlight=snapped

this is where the £4600 'estimate' was found.

Thanks for the tool advice - how does the tensioner work - do you need a spring gauge?

Like said you could get a decent new RS for that money. I think thats why most go for the 1.5k transplant in your shoes.
But if you can check the damage yourself then its worth a try.

 

[Nicolasticity]

Big thanks for all the help - really understand what to do now!

Cambelt and tensioners all good and the belt tension is also OK - however the accessory belt has moved one rib loser to the engine and is looser than I think it should be - its also breaking up and I found a piece of twine inside the timing belt cover - so did that get wrapped in the crank and allow the belt to jump? You can see the damage on the left of the first pic. If you look at the 3rd photo there is at least 1/8th of the belt missing in one area.

Camshafts photo 2 seem OK no breaks, but the engine locks on a valve - it did turn over on the starter before the AA towed me in August - havn't done it since. Question is how many crank teeth have been jumped and if only one how much damage would be caused by 18 degrees of missalignment (I think there are 20 teeth on the crank)

So the plan is buy the tools reset the crank / cams (which have not moved and were marked by Renault when the belt was last changed at 35K and the run it up and see if the valves are OK.

Or is that a bit mad?:lolup:

 

[How15]

if it's slipped a few teeth, enough to cause a piston to catch a valve and stop it cranking by hand, might it not have bent the valve at the point of the slip? you may wanna take the head off and check over it while you've got evrything else off. it's not a massive step further. if you sorted the belts and then it didn't work you'd only have to re-do it all
get some headwork while your at it FTW!

 

[Nicolasticity]

Valves do flex and are ductile - question is if it jumped a crank tooth cos the auzilliary belt lifted it and now its 18 degrees out is that enough to bend the valve - the hand crank feels the valve but it is not solid ie I believe I could hand crank it through - starter also would do it - I was thinking put the belt back connect up min and with belt exposed fire it up for 10 secs - it would let me know if a valve was bent - guess I could do a compression check first with the belt in the right place - need a bottle for the fule pipe mind - dont want that going off..

 

[ditz]

all this talk of teeth is wrong, its not timed up on teeth at all a "tooth" out on that engine is HUGE

all 3 pullies are 3 floating, the crank is physically locked at tdc (not via the pulley) and the cams are locked at the rear of the engine.... then all pulleys spin free on the shafts.

its probably spun on the crank, in which case you wont tell by looking at it, you need to strip it apart and time it up with the tools, but dont crank it anymore untill thats done as a starter motor will bend valves and if it locks its probably already had it

 

[foxspeed]

all this talk of teeth is wrong, its not timed up on teeth at all a "tooth" out on that engine is HUGE

all 3 pullies are 3 floating, the crank is physically locked at tdc (not via the pulley) and the cams are locked at the rear of the engine.... then all pulleys spin free on the shafts.

its probably spun on the crank, in which case you wont tell by looking at it, you need to strip it apart and time it up with the tools, but dont crank it anymore untill thats done as a starter motor will bend valves and if it locks its probably already had it

spot on fella :approve:

 

[Nicolasticity]

when you say free floating I understand that the pulleys are all free until the engine is set (TDC tool and cam alignment ) and then you clamp the pulleys to the crankshaft and the camshafts so the pulleys become fixed - sorry for being thick but at some point there needs to be a positive lock up of the system to allow the drive via the cambelt?

 

[SkidMarx]

Pulleys are only fixed to the crank/ cams by friction. If the two mating faces slip thats where the timing moves out.

 

[J-Key]

Damn i hate hearing these cam belt snapping stories

it happened to me and i bought a new engine @ 25k miles. got the engine and fitting done for a total of £800 in the end which wasnt bad

 

[ben_p]

when you say free floating I understand that the pulleys are all free until the engine is set (TDC tool and cam alignment ) and then you clamp the pulleys to the crankshaft and the camshafts so the pulleys become fixed - sorry for being thick but at some point there needs to be a positive lock up of the system to allow the drive via the cambelt?

I.e there is no woodruff keys on the crank or the pulleys

Its all friction fittings, i doubt the belt would "jump" a tooth, more like the crank pulley has slipped when the AUX belt went into it.

Without taking the head off it would be hard to check for bent valves, so i would get hold of the timing tools, try fit them and see if it all lines up..

if not.. re-time it and hope LOL

 

[ben_p]

Just thinking... you could try see if the timing was way out without using the tools..

Just use a E14 socket on the crank plug, roll it round to TDC (make sure you dont line up a balancing hole) slot a 7mm drill bit into the hole (I think its 7mm)

Then remove the cam end oil plugs, see if the slots are any where close to horizontal..

if there way out then the crank / pulleys have slipped

 

[SkidMarx]

8mm mate i think

 

[ben_p]

cool, well thats gotta be worth a shot, will only take 5 mins

 

[sarge16v]

am in the same boat mate,

 

[JEEV2002]

the £4600 quote is for my 182! :S ...... and im feeling for you at the mo what a pain in the backside it is.

As all the professionals i sought advice from when thevehicle failed they all said these engines do create one hell of a mess internally.

Let us know your findings either way.

Regards,

Jeev

 

[Nicolasticity]

After much wet weather (I am doing the job in the street) I have found the root cause - the auxilary belt broke up and a small piece went between the cambelt and crank pulley which allowed the cambelt to ride over the crank pulley - see pic 1 & 3. Pic 2 is the bits pulled out on the valance - sorry about the focus here.

Did not go for the head option(one on Ebay in Swansea at £125) as I set the cams and crank (using a bar to find TDC which is what we used on outboards and American stendrives) and now it turns over OK by hand (can feel the valves lifting but they are not stiff just strong spring feel) - would like to do a compression check on the starter before firing her up but is it OK to turn the engine with all the systems not wired in - ie on the starter but no sensors or ignition connected? Obvously worried about the Renault computer and big earth leakges.

In the street it aint easy to find the TDC plug manual looks like gearbox end back of motor?

 

[Nicolasticity]

cool, well thats gotta be worth a shot, will only take 5 mins

Im a bit lazy - used a 4mm bar to get TDC - where is the plug not easy to see in the street...

 

[sideways danny]

the plug for the crank locking hole is next to the dipstick tube. there's also a gap in the gearbox bellhousing where you can see the flywheel and there is a mark on the box and the fly you need to line up for accurate TBH alignment. just using the hole can still give a little variation in my experience

 

[JEEV2002]

thats exactly what happened to mine.. Renault should stand up and admit common points of failure.

 

[bmh.01]

I wouldn't even bother compression testing it tbh, if that hasn't bent valves i'll eat my proverbial hat.

thats exactly what happened to mine.. Renault should stand up and admit common points of failure.

They did hence dropping the aux belt from 72k to 36k on the service schedule.

 

[Nicolasticity]

Good call - did the compression test nought! Turned over well and sounded OK no odd noises

Head off (once I got an E14 torx on it) and yes indeed all intake valves bent. No marks on exhaust but they look in the picture like they have a slight bend. Belt was still intact but one slipped crank tooth is worth a whole heap of trouble.

ALL THIS FROM A MINOR FRAYED (NOT SNAPPED) AUXILIARY BELT - BE WARNED!

 

[sarge16v]

Good call - did the compression test nought! Turned over well and sounded OK no odd noises

Head off (once I got an E14 torx on it) and yes indeed all intake valves bent. No marks on exhaust but they look in the picture like they have a slight bend. Belt was still intact but one slipped crank tooth is worth a whole heap of trouble.

ALL THIS FROM A MINOR FRAYED (NOT SNAPPED) AUXILIARY BELT - BE WARNED!

your lucky mate i have snaped valves and marked pistons

 

[Nicolasticity]

Job now complete and car running fine. (I built in in the road - busy job long winter.

Many thanks to all those that helped (Fred you a star) its been an interesting job. I have learned that;

• auxiliary belts are a pain and that they can fail at 25k
• setting camshaft needs care -it is possible to have inlet 180 degrees out and turn over engine OK by hand
• cambelt tensioner is a clever little thing, turn the engine over and reset itand only turn it it in one direction
• cambelt tensioner is a spring hence cambelt is not as tight as on say a Pinto - push it and watch the tensioner move
• dont just undo the auxiliary tensioner as a chipped pulley wheel costs £130 for a new one or £110 with aux belt and bearings
• Use the Renault tools to lock and hold the cams especially after a cambelt change as garages overtorque bolts/nuts and use loctite.
• take it steady..

 

[Tom|Nbk]

Wow nice write up and good job. Here is the proof that Aux belt failure can kill an engine!

Just had my Aux belt changed with new tensioner and pully so I'm definetely glad I chose to do it now since it was slipping.

 

[micallef1990]

am on the same boat too mee thinks.