Cambelt snapped .... just changed by garage
Discussion
In my experience ,a cambelt failure is normally triggered by something else ,ie water pump failure or a tensioner going ,or even foreign bodies within the drivebelt system .That is not to say belts dont just fail on their own ,I've seen it happen .
A belt failing shortly after renewal is actually pretty common ,and if you think about it makes sense as a faulty or incorrectly fitted belt or tensioner wont last long.Most belt failures seem to happen when moving away from rest ,as that is when the valvegear buts the most strain on the belt .You need to be very fortunate to avoid serious cylinder head damage though ,whatever speed they let go at!
A belt failing shortly after renewal is actually pretty common ,and if you think about it makes sense as a faulty or incorrectly fitted belt or tensioner wont last long.Most belt failures seem to happen when moving away from rest ,as that is when the valvegear buts the most strain on the belt .You need to be very fortunate to avoid serious cylinder head damage though ,whatever speed they let go at!
Matt_N said:
A short engine is generally described as the block (bottom end) and head with no ancilaries. So you use the next engine but all the components off the old engine, inlet manifold, alternator etc...
Indeed, but the point being made is that a cam belt failure will tend to wreak havoc on the head (bent valves, broken guides, broken finger finger followers, even broken cams) rather than the bottom end, though some engines also seem to be prone to big end damage after piston/valve contact. A short engine would be next to useless by itself in the case of a timing belt breaking on an interference engine.bigjobbo said:
My apologies, surely "astra" being the operative word there!
Edited by Mr2Mike on Thursday 4th June 12:11
Mr2Mike said:
Matt_N said:
A short engine is generally described as the block (bottom end) and head with no ancilaries. So you use the next engine but all the components off the old engine, inlet manifold, alternator etc...
Indeed, but the point being made is that a cam belt failure will tend to wreak havoc on the head (bent valves, broken guides, broken finger finger followers, even broken cams) rather than the bottom end, though some engines also seem to be prone to big end damage after piston/valve contact. A short engine would be next to useless by itself in the case of a timing belt breaking on an interference engine.Edited by UpTheIron on Thursday 4th June 12:33
Edited by UpTheIron on Thursday 4th June 12:33
Replied with jest! I apologise for the offending comment.
In my previous statement, i said i had never experienced such failure when i have fitted one. Hence, if one was to return shortly after fitting, there would be a brown moment, and the thought "what the... have i done to this" .
I have no disrespect for the manufacturer of the parts, any make, but from my experience i will point the finger at the technician.
In my previous statement, i said i had never experienced such failure when i have fitted one. Hence, if one was to return shortly after fitting, there would be a brown moment, and the thought "what the... have i done to this" .
I have no disrespect for the manufacturer of the parts, any make, but from my experience i will point the finger at the technician.
Mr2Mike said:
Matt_N said:
A short engine is generally described as the block (bottom end) and head with no ancilaries. So you use the next engine but all the components off the old engine, inlet manifold, alternator etc...
Indeed, but the point being made is that a cam belt failure will tend to wreak havoc on the head (bent valves, broken guides, broken finger finger followers, even broken cams) rather than the bottom end, though some engines also seem to be prone to big end damage after piston/valve contact. A short engine would be next to useless by itself in the case of a timing belt breaking on an interference engine.bigjobbo said:
My apologies, surely "astra" being the operative word there!
Edited by Mr2Mike on Thursday 4th June 12:11
UpTheIron said:
Short engine - block, head including all the bits you mention that could be broken, but not including ancillaries (as listed by Matt) which would normally be undamaged and simply swapped onto the new engine.
No. A short engine has always referred to a completed bottom end assembly; block, crank, pistons, rods, oil pump, bearings etc. It does not include the cylinder head, sump or any other ancillary parts.Sorry been away from the pc, anyway already answered above.
my time was a while ago and in most cases, back then, the head
and valves were so far away from the pistons that they survived.
Admittedly most modern engines will destroy the head as well.
Belts are a bit better than they were, still can't beat a good
timing chain though.
my time was a while ago and in most cases, back then, the head
and valves were so far away from the pistons that they survived.
Admittedly most modern engines will destroy the head as well.
Belts are a bit better than they were, still can't beat a good
timing chain though.
inthedark said:
Sorry been away from the pc, anyway already answered above.
my time was a while ago and in most cases, back then, the head
and valves were so far away from the pistons that they survived.
Admittedly most modern engines will destroy the head as well.
Belts are a bit better than they were, still can't beat a good
timing chain though.
Er if the belt breaks and the head n valves are a long way away (like in the olden days), there is nothing to cause damage to the engine! When the cambelt breaks it's only the pistons hitting the valves that turns engine to toast.my time was a while ago and in most cases, back then, the head
and valves were so far away from the pistons that they survived.
Admittedly most modern engines will destroy the head as well.
Belts are a bit better than they were, still can't beat a good
timing chain though.
To the OP, taking the car back to the "offending" garage, might be a bad idea. They might not be as impartial as you want them to be viz-a-viz mode of failure!
Bert
750turbo said:
deeps said:
When one snaps (within it's life span) it's usually due to something else going wrong, such as a siezed tensioner. Even then a belt will squeel loudly for miles before it lets go completely. I once drove 100 miles with a siezed tensioner, and the belt was shredded but still didn't let go. They are strong as fook.
Sorry, I think you are way wrong here, in all my life in the trade you will never get notice that a cam belt is going to break. They will never squeal as they have teeth, and once one lets go, you are past the point of no return.Now, if it was a "fan" belt, "ancillary" belt, or belt not related to the physical valve timing, that is a different kettle of fish. They can squeal there heads off if they require tightening or something needs replacing.
Cam belts do fail, and manufacturers are well aware of it.
I'm not merely speculating, I've had it happen to me on an Alfa Sprint 1.7, which had a flat four 'boxer' engine. One of the tensioners siezed and I thought it was just the fan belt squeeling and carried on for another 100 miles until I got home. Then, on closer inspection and seeing nothing wrong, I removed the cam covers to see the belt running around on the several remaining strands! It had stopped squeeling because the rubber had all worn away. The tensioner had siezed solid, and I was a lucky boy that day.
deeps said:
750turbo said:
deeps said:
When one snaps (within it's life span) it's usually due to something else going wrong, such as a siezed tensioner. Even then a belt will squeel loudly for miles before it lets go completely. I once drove 100 miles with a siezed tensioner, and the belt was shredded but still didn't let go. They are strong as fook.
Sorry, I think you are way wrong here, in all my life in the trade you will never get notice that a cam belt is going to break. They will never squeal as they have teeth, and once one lets go, you are past the point of no return.Now, if it was a "fan" belt, "ancillary" belt, or belt not related to the physical valve timing, that is a different kettle of fish. They can squeal there heads off if they require tightening or something needs replacing.
Cam belts do fail, and manufacturers are well aware of it.
I'm not merely speculating, I've had it happen to me on an Alfa Sprint 1.7, which had a flat four 'boxer' engine. One of the tensioners siezed and I thought it was just the fan belt squeeling and carried on for another 100 miles until I got home. Then, on closer inspection and seeing nothing wrong, I removed the cam covers to see the belt running around on the several remaining strands! It had stopped squeeling because the rubber had all worn away. The tensioner had siezed solid, and I was a lucky boy that day.
I remember the first time I set me eyes on a timing belt, on an old Nissan Sunny, I thought "That will never work" it did.
Bring back chains though
A timing chain is fine but noisy.
They can break too, the longer chains on V8s and things (especially a twin cam v8).
They also stretch though I'm not sure if this affects the engine's running or not.
The first thing that came to mind in this post is, was the tensioner replaced? Sometimes people will opt not to have the tensioner changed, in which case if it subsequently breaks after cambelt change then that's kind of bad luck and probably not the garage's responsibility.
I can't imagine many garages just turning their back on this guy though... sounds like he'll be fine.
They can break too, the longer chains on V8s and things (especially a twin cam v8).
They also stretch though I'm not sure if this affects the engine's running or not.
The first thing that came to mind in this post is, was the tensioner replaced? Sometimes people will opt not to have the tensioner changed, in which case if it subsequently breaks after cambelt change then that's kind of bad luck and probably not the garage's responsibility.
I can't imagine many garages just turning their back on this guy though... sounds like he'll be fine.
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