Cambelt failure - pics

As some may know, my Coupe threw its aux belt into the cambelt at Curborough a couple of weeks ago - Paul has now found the time to get the cylinder head off - it's now clear that the belts went as the throttle was lifted at very high rpm, as the damage is considerable - here's a few pics...

Remember - all of this damage was caused by a cheap-to-replace aux belt - here's what's left of it

The cambelt didn't fare any better - note the small piece of alloy casting...

...which was a piece of the oil pump housing

The good news - six of the valves aren't bent....

All of the inlet valves showing contact marks

However, the pistons are thankfully OK

Close-up - I'm very pleased with the condition - shows the fuelling is good

Slight marking discovered at the top of the bores on a couple of cylinders

Another indication of good fuelling - this manifold is off to Barbz for matching to a new head

So - it looks like a rebuild is going ahead. Paul is going to pull the pistons out anyway, just to make sure that the rings are free in the grooves (the shock can sometimes trap them). Also, on Barbz's advice, we're going to replace the big end shells, even though they were only done 100,000 miles ago when the Accralite pistons were fitted.

This cylinder head was one of Barbz's early ones - in the seven years or so since I had it fitted, I reckon it has paid for itself several times over, in the form of improved fuel consumption - my MPG jumped by around 5mpg after it was fitted, and with my mileage at 30,000 a year, I soon got my money back and started making a profit.

Barbz will be building a new head for me, using all of the knowledge he's built up about Coupe heads in the last seven years. However, because there is no damage to my current head, I will be having new valve guides and replacement valves fitted and I will be selling the head, in order to recoup some of the costs. So - if anyone is in the market for a genuine, proven Barbz head at a discount price, let me know (or you can buy as-is and fit your own valves and guides.

The moral of this story is that aux belts are very cheap to replace - cylinder heads are not - my car is probably one of the best-maintained on the forum (aux belts were done a couple of years ago), but this still happened - I will be changing my aux belts annually from now on.

What nightmares are made of!

Carnage,

Most failures cause the crank pulley to eat the oil pump.
Nice to see Paul doesn't reuse the crank pulleys after failure.

The one I featured on my website put so much force on a new cambelt that it sheared the exhaust pulley off the camshaft.

A reminder that these aux belts should be replaced yearly minimum on high powered cars.

Anyway never a better time to get Barbz to build you a 2.5 then I can have some competition at curborough next time
And a belt guard if your going to maximise the use of the aux belts.

Some of those pics are quite shocking! For how much it costs I think I'll change the aux belt every year from now on.

No competition - I'll beat your time with a measly 400-ish bhp and 2 litres....

I can't afford to get Barbz to build a 2.4 / 2.5 and in any case, mine is fast enough - going to concentrate on handling now

While the car is at Paul's, waiting for the new Barbz head, the rear subframe is coming off and having polyurethane bushes fitted, and a new 24mm Whiteline rear ARB. New front discs and Carbotech pads will also go on, plus a pair of new wishbones (bottom ball joint has play at both sides)

With the Quaife, it was already handling very neatly, but these changes should help it along quite nicely....

2.5 is extremely economical.

What bushes do you use for the subframe as mine have been shot for years?

Poor old long suffering Wifey I think some flowers are in order...!

This cylinder head was one of Barbz's early ones - in the seven years or so since I had it fitted, I reckon it has paid for itself several times over, in the form of improved fuel consumption - my MPG jumped by around 5mpg after it was fitted, and with my mileage at 30,000 a year, I soon got my money back and started making a profit.

Barbz will be building a new head for me, using all of the knowledge he's built up about Coupe heads in the last seven years. However, because there is no damage to my current head, I will be having new valve guides and replacement valves fitted and I will be selling the head, in order to recoup some of the costs. So - if anyone is in the market for a genuine, proven Barbz head at a discount price, let me know (or you can buy as-is and fit your own valves and guides.





You are joking surely Nigel. I would not touch that head if you paid me !!

Why? - it has bent valves, nothing more.

Painful viewing those pics

Nigel - you must get Paul to fabricate an aux belt guard for you, would have saved all of this.

Mine has saved me from 2 aux belt failures, once on a dyno and once whilst driving locally around Bristol. One time the aux belt was less than a year old.

These are surely THE best preventative mod for our cars, for the minimal outlay saved a lot of £ for certain

Because in my opinion if someone is going to have a torqueitalia stage head, then i cant possibly see that buying a head that has had a severe jolt etc would be a sound investment.
We / you know how expensive tuning a coupe to reliable high horse power is.

So why on earth would taking such a risk with that head be a sound tuning investment.

I realise that many may not agree,but its my opinion.

Nigel, bad times. Mine went at low throttle and caused similar damage, so I think you've been Lucky. How you haven't thrown the towel in yet. I would have.

With regards to the aux belt I'm almost certain now that it isn't just an age related problem. With the way they all peel to give a whip on the inner edge it has to be a runnout problem or pulley alignment.

It got me thinking. Mine was a goosed power steering support bearing causing runnout issues. I believe proccy's was found to be an alignment issue of the alloy ancillary mount. I wonder if you have an underlying problem, crank end-float for example?

I also agree with this.

Like Nigel said, only the valves got bent. With new valve guides and valves, as long as they are seating properly, there would be nothing wrong with it.

Post 80's engine development took into consideration that most engines would have to be an interference fit to optimise valve lift.
This meant that future engine development would utilise various valve guide systems.
The valves are extremely strong and would take the weight of the car on its strongest point.
However just like a formula 1 car's wishbones strength these valves were designed to bend given abnormal forces from a certain angle.
The side effects are damage to the guides only.
A very easily replaced component:

It's no different having a faulty track rod end.you only need to replace the joint not the rack.

The main concern in such a failure would be the potential damage to the pistons or the big end bearings.
This is currently being addressed on the rebuild .

The valves are extremely strong and would take the weight of the car on its strongest point.
However just like a formula 1 car's wishbones strength these valves were designed to bend given abnormal forces from a certain angle.
The side effects are damage to the guides only.
A very easily replaced component - JBT -

Sounds spot on to me. The forces seen on the head were those sufficient to bend the valves. If they weren't the pistons would have see more force and so more damage.

Good luck with the rebuild Nigel

Nigel why are you having another head done rather than use this one?
Is it a stage 1 effectivly and you now going for stage 2 and more power as if not whats the point in having another if your only having the same?

Hi Dave

I wondered that as well, but Barbz said he would prefer to work from a 'virgin' head, rather than re-work mine.

This suits me fine, as I'll be able to recover some of the cost by selling the original head once its had new valves and guides fitted

I'm doing something a bit more enhanced for his current setup.

Well thats ok then but as nigel said himself there is no need for another head just that you are doing somthing diffrent for him. by the looks of his comment above it looks like he is having the same though not somthing diffrent and also looks like he was/is unaware of this?

Then, i'm sure he will be pleasantly suprised.

Dave your right.
It makes more sense for Barbz to wait a few weeks for Nigel to Remove the head and send it down to him than it does to rework one he knows is good and in his workshop.

John no need for the sarcasm I was only wondering why Nigel would get another head done when it would be cheaper to have the existing one sorted if he is only having the same spec so thanks for your comment

Always need for sarcasm with you David.
Your a funny guy after all.

Such a simple question inspired the response.

Guys - I spoke at length with Barbz at the AGM a couple of weeks ago. I also assumed that he would re-work my head, rather than start with a stock head.

However, he said that he would prefer to work with an untouched head, as he would be able to apply everything he's learned since he did mine all those years ago.

Also, Barbz will be doing something with my manifold, I believe around the collector area.

Finally, he'll be specifying some custom cam settings for my C&B cams

I'm not after big power gains, although if I get some more, I won't be complaining. My main aim is to increase the low and mid-range and to improve spoolup. My turbo is capable of rather more than it gave last time Leighton mapped the car (mostly down to the injectors being maxxed out), so I'm hoping that a new head, some new injectors and a remap will realise the true potential of the billet compressor wheel on the GT3071.

Along with the handling tweaks that will be fitted while its waiting, the car should come back feeling pretty good.

Sorry again Nigel
So it looks like it let go at high revs when I lifted off to brake at the end of the straight? Strange I didn't notice any lights or lack of engine note until I had turned in to the corner. Maybe you would have noticed it immediately knowing your car more intimately.
I look forward to seeing it running again mate.

I didn't even mention getting the head reworked as it would not need to be reworked and as my question was to Nigel not to you so there was no need for your response thanks again.

Nigel sorry for taking it OT but I'm glad your getting it all done and I'm sure you can get a few more horses from it now as had been said Barbz knows a fair bit more about it now than what he did 7 years ago so best of luck

Senny Dave - I would have been happy with new valves and guides, but Barbz made me an offer I couldn't refuse, which included some new work that couldn't easily be carried out on my existing head. Don't ask me what it is - it's well beyond my understanding, but if Barbz says it'll be better than what I've been running so far, I believe him

Fishy Dave - yes, it looks like the aux belt started to come off at high revs, probably as the throttle was lifted - however, it could have been a couple of seconds before the shredded belt found its way into the cambelt. Again - don't be sorry - there was nothing you could have done to my car that I wouldn't have been doing to it when I next drove it - in fact I would probably have been driving it harder than you would ever have done - just one of those things.

Thats fine as do I, I just wondered why you were going with a new head as it seemed you were only after the same power and as we know the rebuild isn't cheap without the cost of another head, But I'm sure the extra power will also be good and liked

It's an open forum Dave ,and the seemingly stupid question held no relevance to the initial post, more to belittle a subject previously answered.

So on that note I have more right to comment as a paid fccuk member and coupe owner as anyone.

John how is this a stupid question how does it belittle somthing previously answered? I asked Nigel as I'm intrested

Come on guys, let's all be nice.

It's bad enough Nigel loosing an engine while Dave was driving so let's keep this relevant to the thread.

This issue is what has kept me below 350Bhp for so long.

Didn't Flea go through several repeated cambelt failures when his coop was running around 450Bhp?

I think all the top powered coupes in the day suffered belt issues.

I have been lucky enough not to have had any this far despite having 2 shred.
Expensive nightmare.

Aux belt failures. Not Cam.

it can happen at any time.
i was lucky to catch mine at the right point.
it already started going round the the crank pulley.
had to cut it off and remove each bit, one strand at a time.

scray stuff.

and that was a new belt only 6 / 9 months old.

A friend at work asked me to look at his car (Skoda Fabia) last week and to my horror his aux belt was frayed to hell - and about half the thickness it should be. He said it had been like that for about 6 months

The aux belt was very wide though, maybe 1.5 inches.

Sorry to here about the belts Nigel. Hope the new head and headwork doesn't cost to much.
I recall reading something about the 2.4 engine having a slightly different design on the belt system? can some one enlighten me to the specifics and why its not possible to move over this factory part

Stilo system Sam is different but coupe with the stilo engine must remain the same as the ancilliaries and bracketry are different.

You could mount a dynamic tensioner to the original mounts as opposed to a static tensioner.
However the downside is you would also need to run an inertia alternator to stop the belt "bouncing" on lift off.

So the 2.4 stilo alternator and 20vt one are different then If I understand correctly

Yes the mounting points vary considerably but the engine block mounting point remains the same.

Thanks Johny, so it doesn't seem like a cheaper easier option over a guard then. I just have not run across the same aux belt eating issue with the 2.4 stilo, seems limited to the coupe.

So far the option I offer seems to of saved numerous engines .
Nothing's guaranteed but every precaution helps.

So there is a cheap solution at the moment.

I'm looking at a redesign of either the crank pulley or the aux tension side over the winter so watch this space.

As it would happen Sam, we have just completed a top end rebuild on a Stilo 2.4 with... yes you guessed it, aux belt failure that resulted in 15 bent valves.

I had a belt go last week on a Punto GT 20vt conversion, ironically the belt split all the way down the midddle with one half shooting out through the rear view mirror and the other seconds away from wrapping itself around the crank pulley. Luckily I stopped the engine just in time, so it lives to fight another day. However, it will be receiving an FC belt guard upgrade, something I am proud to say remains undefeated!

The last bit isnt strictly true Flea.

That IS lucky.

Bad luck Nigel. Sorry to see this happen to your lovely car.

As always, you'll be back - stronger.

I think Barbz now fits a slightly shorter belt with he's guards so they are tighter and have less chance of jumping?

Barbz did mention that he could supply a different belt which reduces the chance of failure - I will be taking his recommendation

What grieves me is that this engine has done a quarter of a million miles, the last 200,000 of which have been in my hands. Its had a pretty hard life in this time, without any belts issues.

It was simply my slight lack of attention that's caused the problem - if I'd replaced the belts annually, we wouldn't be reading this thread (or at least we wouldn't be reading it about my car....)

My opinion is that a correctly fitted, aligned and tensioned belt that is in good condition simply doesn't come off. However, one or more problems, such as poor condition, slackness, or an alignment problem caused by a tensioner or pulley is enough to leave the belt vulnerable, with a 50/50 chance of engine damage, depending on which way the belt decides to travel when it comes off

Flea, were the belts with in there service schedule? Also seems a fact that the Stilo isn't a car that's looked after particularly well sadly.

I wouldn't beat your self up Neil, changing AUX belts on a yearly bases is not something you should really need to do.

I think I know what you mean but who is Neil, has he lost a belt too?

I think that's the standard iPhone spell corrector.

Darn it, sorry Nigel

LOL - I've been called a lot worse....

Glad to read you're sticking with it Nigel. Good luck in getting it running again.

Marco....

As it happens, yes, but it was a long time ago, in a far country, and besides, the wench is dead.



There *are* lots things worse to be called; 'tis true.

Update

Mmmmm - shiny

Pistons are out and have been checked - all fine

Big end shells are out - No1 shells were slightly worn, but all the rest were fine - any ideas? All are being replaced as a precaution

It should all start going back together next week, along with some non-standard valve timing devised by Barbz

Then, it's off to Leighton for some 630cc injectors and a remap session

big end bearing measurements?

Not sure - Paul looked at them, said four were fine and one was showing signs of wear, so we decided to replace the lot.

Big end shells are out - No1 shells were slightly worn, but all the rest were fine - any ideas?

piston and rod weight difference to the rest. they are close matched from the factory but still will be out alittle bit

All the pistons and rod assemblies are balanced to within half a gram of each other - Paul got really serious about it when he built the engine (stock tolerance is something like 20 grams)

Is that a standard head cast wise ?
I ask as mine doesn't have the extra casting to the left round the spark plug recess :|

sorry meant journals, not shells

as now would be the time to source a good one if this one is worn....

Looks like Paul will be working a few late nights then from the look of the work he had on today

I have asked Barbz the same thing - don't remember seeing it on my original head

looks like that engine could do with some paraflu!