Line of attack with a failed timing belt...
Discussion
Hello
I have a friend with a 307 1.6 petrol that he has neglected to change the timing belt on (original belt after 12 years!) and it has snapped.
As the car is now worthless we are wondering if we give it a weekend or two if it can be revived.
My friend wants to replace the belt and see what happens, I feel however if the belt has gone while driving it will have bent valves and we should prob pop the head off before we do this as it will be time wasted otherwise?
Any pointers to how we check if there is defo bent valves?
Only taken part in one timing belt change once about 5 years ago but as we haven't a lot to lose I feel we should give it a go.
Any help would be great, cheers.
I have a friend with a 307 1.6 petrol that he has neglected to change the timing belt on (original belt after 12 years!) and it has snapped.
As the car is now worthless we are wondering if we give it a weekend or two if it can be revived.
My friend wants to replace the belt and see what happens, I feel however if the belt has gone while driving it will have bent valves and we should prob pop the head off before we do this as it will be time wasted otherwise?
Any pointers to how we check if there is defo bent valves?
Only taken part in one timing belt change once about 5 years ago but as we haven't a lot to lose I feel we should give it a go.
Any help would be great, cheers.
Question is, is this an "interference" engine or not?
Many engines are not - the crank can rotate without the camshaft(s) and not damage the valves - but the Peugot 307 1.6L after 2005 is an interference engine.
I don't know about before that.
Fitting a new cam belt to the later engine is likely to be a waste of time. You should remove the cylinder head and inspect valves and pistons for damage. First, you could try turning the crank by hand, feeling for resistance and listening for nasty noises, stopping at the first sign.
Easiest and quickest way out is a used engine from a scrapper if you can find one.
John
PS See: http://replace-timing-belt.com/how-to-replace-timi...
Many engines are not - the crank can rotate without the camshaft(s) and not damage the valves - but the Peugot 307 1.6L after 2005 is an interference engine.
I don't know about before that.
Fitting a new cam belt to the later engine is likely to be a waste of time. You should remove the cylinder head and inspect valves and pistons for damage. First, you could try turning the crank by hand, feeling for resistance and listening for nasty noises, stopping at the first sign.
Easiest and quickest way out is a used engine from a scrapper if you can find one.
John
PS See: http://replace-timing-belt.com/how-to-replace-timi...
Edited by tapkaJohnD on Wednesday 27th July 10:28
If it's just a couple of bent valves you can replace them individually and fix it fairly cheaply. If it's a lot of valves and broken rockers etc. you might be better with a scrap head.
Bent valves can be quite subtle, sometimes you can barely see it. You can pour parrafin or petrol into the port to see how fast it leaks past the valve, or if you grind the valve a little you can see if theres one bright spot with the rest not making contact.
Bent valves can be quite subtle, sometimes you can barely see it. You can pour parrafin or petrol into the port to see how fast it leaks past the valve, or if you grind the valve a little you can see if theres one bright spot with the rest not making contact.
Bennachie said:
307 1.6 16v petrol is interference engine. Sadly its goosed.
I did think this but was trying to be hopeful.Scrap head - skim? - and back together is my personal line of attack but will see what he wants to do, if I can get the manifold off easily then cant see it being too bad a job... unless the pistons are a mess.
steveo3002 said:
yeah get askign around if that engine is interference or no
if it is then dont waste your time fitting a belt , first step would be head off then decide if its cheaper to fit new valves or buy a used head , probably doable over a weekend for a few hundred
It's not a waste of time to fit a new belt, you already have to start dismantling the same stuff you'd need to to remove the head. Once the timing cover and old belt remnants have been removed, you'll lose nothing but maybe a 1/2 hour of time to fit a new belt (but not the covers etc.) and perform a compression test.if it is then dont waste your time fitting a belt , first step would be head off then decide if its cheaper to fit new valves or buy a used head , probably doable over a weekend for a few hundred
Chances are high it HAS bent one or more valves, but for the minimal effort required you could be lucky and if not you know which cylinders have bent valves (sometimes they can be bent such a tiny amount that you can hardly see it, but compression will suffer).
Edited by Mr2Mike on Wednesday 27th July 14:15
Had a gander at the belt and it looks like it has jammed or got stuck causing one of the pulleys to rip through it. Belt was pretty rotten tbh teeth had cracks in them.
Will strip further and inspect pump as I think that has jammed causing the mess.
The cams are also solid, this would tell us the valves are all bent wouldn't it?
Will strip further and inspect pump as I think that has jammed causing the mess.
The cams are also solid, this would tell us the valves are all bent wouldn't it?
Edited by bungz on Wednesday 3rd August 09:16
Yes,it's a very straightforward engine to work on.Before you start I would surgest you do some pricing to decide if its worth it? If the body is nice and you have spent money on the rest of the car,maybe? it's always a dilemma with an old car in need of a major repair.If you decide to repair it,do it properly and keep it. It needs a cylinder head,gasket kit,head bolts,cambelt kit,water pump,plus various other "odds".If you go for a reconditioned exchange head that parts list could set you back £750 - £850 ?? pistons will be OK,they will just have a little knick where the valve hit.
You could get a second hand head for what? £100? but as with all used goods,you pay and take a chance.
You could get a second hand head for what? £100? but as with all used goods,you pay and take a chance.
bungz said:
It seems to be fairly straight forward to get a new head on it.
Will get head off and have a gander, is it likely the pistons and rods be ok?
Impossible to say as you've been a bit light on one relevant piece of info, i'm surprised no-one has asked; How fast was the engine turning and how quickly (if at all) was the car travelling when it snapped?Will get head off and have a gander, is it likely the pistons and rods be ok?
Tickover: Chance of repair.
Bouncing off the rev limiter on the M1 at 4am: Zero chance of repair.
Evoluzione said:
bungz said:
It seems to be fairly straight forward to get a new head on it.
Will get head off and have a gander, is it likely the pistons and rods be ok?
Impossible to say as you've been a bit light on one relevant piece of info, i'm surprised no-one has asked; How fast was the engine turning and how quickly (if at all) was the car travelling when it snapped?Will get head off and have a gander, is it likely the pistons and rods be ok?
Tickover: Chance of repair.
Bouncing off the rev limiter on the M1 at 4am: Zero chance of repair.
Spangles said:
It doesn't make a lot of difference, there's enough momentum in an idling engine to bend the same amount of valves as at 6k.
Surely an engine spinning at 800rpm will do less damage than one spinning at 6k.The one spinning at 800rpm will stop turning sooner (after the belt breaks) therefore will impact the valves many times less than the other. Could be the difference between simply bending the valves and in the other case, breaking off the valve heads and hammering them into the piston/head.
DuraAce said:
Surely an engine spinning at 800rpm will do less damage than one spinning at 6k.
The one spinning at 800rpm will stop turning sooner (after the belt breaks) therefore will impact the valves many times less than the other. Could be the difference between simply bending the valves and in the other case, breaking off the valve heads and hammering them into the piston/head.
Bent is bent. Valve heads rarely break off from a broken timing belt.The one spinning at 800rpm will stop turning sooner (after the belt breaks) therefore will impact the valves many times less than the other. Could be the difference between simply bending the valves and in the other case, breaking off the valve heads and hammering them into the piston/head.
Spangles said:
Evoluzione said:
bungz said:
It seems to be fairly straight forward to get a new head on it.
Will get head off and have a gander, is it likely the pistons and rods be ok?
Impossible to say as you've been a bit light on one relevant piece of info, i'm surprised no-one has asked; How fast was the engine turning and how quickly (if at all) was the car travelling when it snapped?Will get head off and have a gander, is it likely the pistons and rods be ok?
Tickover: Chance of repair.
Bouncing off the rev limiter on the M1 at 4am: Zero chance of repair.
The correct answer has been posted: Take the head off and look.
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