Timing/Cambelt has snapped
21 November 2010, 08:22 PM
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Timing/Cambelt has snapped
Well after a week i finally know whats wrong with the scooby,ive snapped the timing belt.I wasnt going hard at the time probably about 3000rpm.
So where go i from here new belt and try it or?
So where go i from here new belt and try it or?
21 November 2010, 08:24 PM
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Theoretically, it will have bent some valves. I suppose it wouldn't hurt to investigate a bit further before actually pulling the engine out.
21 November 2010, 08:39 PM
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21 November 2010, 08:56 PM
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21 November 2010, 10:05 PM
#11
You can turn the engine over by hand even with bent valves.
When the cambelt breaks, its not normally the piston coming up and causing the damage - its the Inlet valves hitting the exhaust valves first which bends/tips them due to the 52 degree angle of the valves in the head.
At 3000rpm, will be very suprised if you get away without any valve damage.
If there is no damage - go out and buy a lottery ticket as you will have been very lucky.
Mick
When the cambelt breaks, its not normally the piston coming up and causing the damage - its the Inlet valves hitting the exhaust valves first which bends/tips them due to the 52 degree angle of the valves in the head.
At 3000rpm, will be very suprised if you get away without any valve damage.
If there is no damage - go out and buy a lottery ticket as you will have been very lucky.
Mick
21 November 2010, 10:08 PM
#12
You can turn the engine over by hand even with bent valves.
When the cambelt breaks, its not normally the piston coming up and causing the damage - its the Inlet valves hitting the exhaust valves first which bends/tips them due to the 52 degree angle of the valves in the head.
At 3000rpm, will be very suprised if you get away without any valve damage.
If there is no damage - go out and buy a lottery ticket as you will have been very lucky.
Mick
When the cambelt breaks, its not normally the piston coming up and causing the damage - its the Inlet valves hitting the exhaust valves first which bends/tips them due to the 52 degree angle of the valves in the head.
At 3000rpm, will be very suprised if you get away without any valve damage.
If there is no damage - go out and buy a lottery ticket as you will have been very lucky.
Mick
This car is turning into a money pit!
21 November 2010, 10:56 PM
#14
If you fire it up even slightly bent valves will be heard. I had this after sourcing some second hand heads. A loud ticking that shouldnt have been there. Took the engine out took the offending head off and sure enough I had two slightly bent valves. The bend on the valves wasnt visible straight away but as soon as I put them into a drill and rotated it slowly you could see the movement in the valve head. I replaced the valves, refitted the head dropped the engine back in and its still going strong 3 years later 
21 November 2010, 10:59 PM
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If you fire it up even slightly bent valves will be heard. I had this after sourcing some second hand heads. A loud ticking that shouldnt have been there. Took the engine out took the offending head off and sure enough I had two slightly bent valves. The bend on the valves wasnt visible straight away but as soon as I put them into a drill and rotated it slowly you could see the movement in the valve head. I replaced the valves, refitted the head dropped the engine back in and its still going strong 3 years later
22 November 2010, 12:25 PM
#16
Put a new belt on making sure its timed up properly and then rotate the engine by hand. If it rotates by hand without issue then its worth attempting to start it. be ready with that key incase you hear anything untoward and turn it off immediately. Any sound that wasnt there before needs investigating properly which will be an engine out heads off job.
Last edited by dazdavies; 22 November 2010 at 12:26 PM.
22 November 2010, 02:29 PM
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i would put the belt on and try moving it by hand , if it does move i would do a compression test by dry cranking, if that was ok which i doubt then i would start it.
btw ive got a set of sti valves but you will need hgs, pulleys at the very least.
shame you are in scotland cos i know someone who would do it at a good price
btw ive got a set of sti valves but you will need hgs, pulleys at the very least.
shame you are in scotland cos i know someone who would do it at a good price
22 November 2010, 06:09 PM
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i would put the belt on and try moving it by hand , if it does move i would do a compression test by dry cranking, if that was ok which i doubt then i would start it.
btw ive got a set of sti valves but you will need hgs, pulleys at the very least.
shame you are in scotland cos i know someone who would do it at a good price
btw ive got a set of sti valves but you will need hgs, pulleys at the very least.
shame you are in scotland cos i know someone who would do it at a good price
Thanks for the offer of the valves they may be needed yet lol
30 November 2010, 09:15 PM
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Well i refitted the new belt and made sure the timing was spot on,because when i done it a few days ago one of the cam pulleys was a couple of teeth out.
After it was done i turned it over by hand for a while and it felt ok so i tried to start it.Its turning over but making no attempt to start.
When i was turning it over the dash clock and lights etc were going off so i thought possibly the battery is flat so ive stuck it on charge until tommorow.
Any thoughts why it wouldnt want to fire?
I have not pressure tested it yet.
After it was done i turned it over by hand for a while and it felt ok so i tried to start it.Its turning over but making no attempt to start.
When i was turning it over the dash clock and lights etc were going off so i thought possibly the battery is flat so ive stuck it on charge until tommorow.
Any thoughts why it wouldnt want to fire?
I have not pressure tested it yet.
30 November 2010, 10:06 PM
#21
Well i refitted the new belt and made sure the timing was spot on,because when i done it a few days ago one of the cam pulleys was a couple of teeth out.
After it was done i turned it over by hand for a while and it felt ok so i tried to start it.Its turning over but making no attempt to start.
When i was turning it over the dash clock and lights etc were going off so i thought possibly the battery is flat so ive stuck it on charge until tommorow.
Any thoughts why it wouldnt want to fire?
I have not pressure tested it yet.
After it was done i turned it over by hand for a while and it felt ok so i tried to start it.Its turning over but making no attempt to start.
When i was turning it over the dash clock and lights etc were going off so i thought possibly the battery is flat so ive stuck it on charge until tommorow.
Any thoughts why it wouldnt want to fire?
I have not pressure tested it yet.
30 November 2010, 10:29 PM
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I was going to test it at the weekend i was just wondering if there could be anything else.
I noticed on club WRX a guy was saying to check the crank line was facing up,i lined up the key tooth that the crank pulley goes onto and made that vertical if that makes sense.I will have to check it tommorow.
I noticed on club WRX a guy was saying to check the crank line was facing up,i lined up the key tooth that the crank pulley goes onto and made that vertical if that makes sense.I will have to check it tommorow.
30 November 2010, 10:31 PM
#23
I was going to test it at the weekend i was just wondering if there could be anything else.
I noticed on club WRX a guy was saying to check the crank line was facing up,i lined up the key tooth that the crank pulley goes onto and made that vertical if that makes sense.I will have to check it tommorow.
I noticed on club WRX a guy was saying to check the crank line was facing up,i lined up the key tooth that the crank pulley goes onto and made that vertical if that makes sense.I will have to check it tommorow.
Always use the line as the timing mark (all pistons are halfway down the bore) when fitting a cam belt, the triangle is the tdc mark.
30 November 2010, 11:38 PM
#26
Word of warning: The above checks will only identify a badly bent valve (i.e one that's been bashed properly), it won't identify minor bent valve(s).
It may "seem" to run, but you may also hear a faint tapping noise. Bit like tappets.
You know that is? As Dazdavies says; its the sound of slightly bent valves hitting the seats off-square. As they bend and straighten, bend and straighten, bend and straighten (etc.) every time they open and close. As the valve spring is strong enough to pull a slightly bent valve closed, the engine will operate and give good compression. Problem is, its a ticking time bomb.
Eventually, a valve stem will seize in the guide, or give way from fatigue dropping a valve head and totally wreck the engine (knackered block, knackered head, knackered piston(s), rod(s) and crank etc).
It may take weeks or months, or the thirteenth time it hits 6000rpm in 3rd gear, for the worst to happen. But without stripping off the heads and removing the valve to check and be 100% sure everything is OK, you are in dangerous and unchartered waters. Unless you can afford to buy a new engine, don't cut corners!
Plus, why did the belt break anyway?
Too many time I heard of people change belts but not pay one bit of attention to the condition of the bearings in the idlers, tensioner, water pump, or fix any oil leaks from the shaft seals; all of which if left unchecked will cause a premature belt failure.
It may "seem" to run, but you may also hear a faint tapping noise. Bit like tappets.
You know that is? As Dazdavies says; its the sound of slightly bent valves hitting the seats off-square. As they bend and straighten, bend and straighten, bend and straighten (etc.) every time they open and close. As the valve spring is strong enough to pull a slightly bent valve closed, the engine will operate and give good compression. Problem is, its a ticking time bomb.
Eventually, a valve stem will seize in the guide, or give way from fatigue dropping a valve head and totally wreck the engine (knackered block, knackered head, knackered piston(s), rod(s) and crank etc).
It may take weeks or months, or the thirteenth time it hits 6000rpm in 3rd gear, for the worst to happen. But without stripping off the heads and removing the valve to check and be 100% sure everything is OK, you are in dangerous and unchartered waters. Unless you can afford to buy a new engine, don't cut corners!
Plus, why did the belt break anyway?
Too many time I heard of people change belts but not pay one bit of attention to the condition of the bearings in the idlers, tensioner, water pump, or fix any oil leaks from the shaft seals; all of which if left unchecked will cause a premature belt failure.
Last edited by ALi-B; 30 November 2010 at 11:40 PM.
01 December 2010, 09:03 PM
#27
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Well the crankshaft was 180 degrees out so i took the belt off and started again.This time it started straight away and was running nicely with no bangs,tick or rattles.
Great i thought until i looked underneath and water appears to be coming out from the water pump,alot of water.
I wonder if the pump had seized or something thus causing the belt to snap.I shut it off asap and packed up the tools because this is the forth night i have been working on the car in subzero blizardous conditions until dark o clock.
I will have a better look tommorow.
Any thoughts?
Great i thought until i looked underneath and water appears to be coming out from the water pump,alot of water.
I wonder if the pump had seized or something thus causing the belt to snap.I shut it off asap and packed up the tools because this is the forth night i have been working on the car in subzero blizardous conditions until dark o clock.
I will have a better look tommorow.
Any thoughts?
