Cam Belt failure
07 June 2000, 05:07 PM
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my car was involed in a front end accident
recently (MY 98),the n/s took most of the impact which pushed the front panel back into the timing covers,the result was that the top n/s pulley shattered throwing off the cam belt.
Ive had a mixed response to this on the outcome of whether the engine has been damaged or not,I spoke to the mechanics at my local subaru dealership & they said the best thing to do was to put on another belt
and compression test it,but speaking to so called other people in the know they said just start stripping the heads off because
99% of the time it has done damage,
I decided to go with subarus advice & fitted a belt (£120) never compression tested it just turned the key & the engine just bursted back into life perfect!
since then the cars been repaired and is due to be collected this week,the engine is sitting on my garage floor waiting to go back in (can`t wait)
But now I have people telling me that the valves could still be bent leading to a lack of performance,
surely you would notice this even with the engine idling or reving it stationary i.e.misfires etc
anyone heard of anything similar.
cheers
Jim
recently (MY 98),the n/s took most of the impact which pushed the front panel back into the timing covers,the result was that the top n/s pulley shattered throwing off the cam belt.
Ive had a mixed response to this on the outcome of whether the engine has been damaged or not,I spoke to the mechanics at my local subaru dealership & they said the best thing to do was to put on another belt
and compression test it,but speaking to so called other people in the know they said just start stripping the heads off because
99% of the time it has done damage,
I decided to go with subarus advice & fitted a belt (£120) never compression tested it just turned the key & the engine just bursted back into life perfect!
since then the cars been repaired and is due to be collected this week,the engine is sitting on my garage floor waiting to go back in (can`t wait)
But now I have people telling me that the valves could still be bent leading to a lack of performance,
surely you would notice this even with the engine idling or reving it stationary i.e.misfires etc
anyone heard of anything similar.
cheers
Jim
09 June 2000, 08:54 PM
#2
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James...
A cambelt going does not always mean engine destruction. It depends on the speed/revs that the car was doing at the time of break!
If it fires up, with no cam rattle (no more then usual!), no smoke (which could indicate a knackered valve,worn bore/piston/ring) and it sounds like it's firing on all 4 cylinders, it should be OK!
The final acid test then, would be to give it a good blat (if the above is OK)!
Shaun.
A cambelt going does not always mean engine destruction. It depends on the speed/revs that the car was doing at the time of break!
If it fires up, with no cam rattle (no more then usual!), no smoke (which could indicate a knackered valve,worn bore/piston/ring) and it sounds like it's firing on all 4 cylinders, it should be OK!
The final acid test then, would be to give it a good blat (if the above is OK)!
Shaun.
09 June 2000, 09:11 PM
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Howdy.
Erm.. why would a knackered timing belt destroy piston rings ?
Cam rattle ? if your cams rattle.. you are fooked... Why would they rattle with no belt ? lol
what happens, is the valve impacts against the pistons. (if you are assuming this as the reason for piston ring damage, then you might as well scrap the pistons and the rods too)
Normally the valves come off worst.
You either snap the head off them.. or bend a stem... or lose a little of the crown.
You can be fortunate when they are hydraulic. Because the belt powers the oil pump. This stops pumping, you loose pressure and the valves collapse. This minimises the damage. Its a bit different on solid valves. It only takes a thou or two to cause damage.
The valves do hit the pistons on our cars - but not all makes do.
But. you might be ok..
J.
Erm.. why would a knackered timing belt destroy piston rings ?
Cam rattle ? if your cams rattle.. you are fooked... Why would they rattle with no belt ? lol
what happens, is the valve impacts against the pistons. (if you are assuming this as the reason for piston ring damage, then you might as well scrap the pistons and the rods too)
Normally the valves come off worst.
You either snap the head off them.. or bend a stem... or lose a little of the crown.
You can be fortunate when they are hydraulic. Because the belt powers the oil pump. This stops pumping, you loose pressure and the valves collapse. This minimises the damage. Its a bit different on solid valves. It only takes a thou or two to cause damage.
The valves do hit the pistons on our cars - but not all makes do.
But. you might be ok..
J.
10 June 2000, 09:12 PM
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I have a Pug 205GTi which suffered a cambelt slippage, producing metallic clonking sounds; on replacing the belt all appeared to be OK, car ran fine and continued to do so for many months. Approx 10 months later the engine started sounding rough at idle (virtually no compression on one cylinder). On removing the head there were 3 bent exhaust valves - one had started to burn and caused the compression loss - the other two were obviously bent once they were removed but didn't show a compression loss! They had been like that all that time....
The moral of the story - just 'cos it runs OK doesn't neccessarily mean that all is well!
Strange but true.
Hope this isn't too depressing?
Rich
The moral of the story - just 'cos it runs OK doesn't neccessarily mean that all is well!
Strange but true.
Hope this isn't too depressing?
Rich
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