trinitom Posted April 2, 2009 Share Posted April 2, 2009 Hi people someone told me a few months ago that the supra doesn't get any engine damage if the timing belt brakes! is that true? in my integra i know if they break can cause big damage to valves etc etc.. thanks.. Quote Link to comment Share on other sites More sharing options...
Nic Posted April 2, 2009 Share Posted April 2, 2009 Yes the 2JZ is non interference, ie. the pistons will not hit the valves if the belt breaks. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted April 2, 2009 Share Posted April 2, 2009 On a car with standard cams, it might not cause any damage. Quote Link to comment Share on other sites More sharing options...
trinitom Posted April 2, 2009 Author Share Posted April 2, 2009 Yes the 2JZ is non interference, ie. the pistons will not hit the valves if the belt breaks. ok thanks, but i presume the car will lose power if that append, since the intake valves and exhaust are not synchronized right? Quote Link to comment Share on other sites More sharing options...
Nic Posted April 2, 2009 Share Posted April 2, 2009 ok thanks, but i presume the car will lose power if that append, since the intake valves and exhaust are not synchronized right? The engine would completely cut out. Quote Link to comment Share on other sites More sharing options...
trinitom Posted April 2, 2009 Author Share Posted April 2, 2009 The engine would completely cut out. right!! thanks Nic regards.. Quote Link to comment Share on other sites More sharing options...
Jake Posted April 3, 2009 Share Posted April 3, 2009 On a car with standard cams, it might not cause any damage.How might it cause damage then? Quote Link to comment Share on other sites More sharing options...
bignum Posted April 3, 2009 Share Posted April 3, 2009 The broken belt could get wrapped around the tensioner and drag it through which could then smash through the radiator and make a big gash in the bonnet:) Quote Link to comment Share on other sites More sharing options...
Burna Posted April 3, 2009 Share Posted April 3, 2009 The broken belt could get wrapped around the tensioner and drag it through which could then smash through the radiator and make a big gash in the bonnet:) You're one of those 'glass is half empty' kind of guys aren't you Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 Yes the 2JZ is non interference, ie. the pistons will not hit the valves if the belt breaks. spot on cam belt can cause other damage though like, spinning your water pump so fast it mucks it up, or snap the tentioner arm, can even spin the cam too fast. if it goes a certain point can also cause oil pump problems!! Quote Link to comment Share on other sites More sharing options...
heckler Posted April 3, 2009 Share Posted April 3, 2009 spot on cam belt can cause other damage though like, spinning your water pump so fast it mucks it up, or snap the tentioner arm, can even spin the cam too fast. if it goes a certain point can also cause oil pump problems!! oil pump? but thats driven by the crank shaft... Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 oil pump? but thats driven by the crank shaft... not on supras, just in general, if the belt snapps at say 6000rpm, and there is no control over the speed of the rotation then it can cause problems, ive seen it before, not much but seen it. i had it on a bmw 535td once, took ages to work it out but thats what it was in the end. Quote Link to comment Share on other sites More sharing options...
heckler Posted April 3, 2009 Share Posted April 3, 2009 not on supras, just in general, if the belt snapps at say 6000rpm, and there is no control over the speed of the rotation then it can cause problems, ive seen it before, not much but seen it. i had it on a bmw 535td once, took ages to work it out but thats what it was in the end. oh, ok - bit of confusion there - concidering this is about a supra engine Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 oh, ok - bit of confusion there - concidering this is about a supra engine my bad Quote Link to comment Share on other sites More sharing options...
heckler Posted April 3, 2009 Share Posted April 3, 2009 my bad lol... i was racking my brain (cell) to think how a snapped belt would affect the pump.. Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 lol... i was racking my brain (cell) to think how a snapped belt would affect the pump.. still looking into supra engines in detail atm, but a senario is, imaging your doing 6000rpm and it snapps. you lose compresion so the engine is free to go wild and spin up if it feels like it, instead of go straight down immediately. at that point the oil pressure does not match what the engine is doing, thus , high oil pressure, causing other problems. i think its mainly more electrnic controlled cars, i.e bmw merc etc. i doubt it on a supra though Quote Link to comment Share on other sites More sharing options...
SimonB Posted April 3, 2009 Share Posted April 3, 2009 still looking into supra engines in detail atm, but a senario is, imaging your doing 6000rpm and it snapps. you lose compresion so the engine is free to go wild and spin up if it feels like it, instead of go straight down immediately. at that point the oil pressure does not match what the engine is doing, thus , high oil pressure, causing other problems. i think its mainly more electrnic controlled cars, i.e bmw merc etc. i doubt it on a supra though It's not free to do anything, it's connected to the wheels! Plus with no compression you have no force on the pistons to do anything other than run at road speed, or coast down if you put the clutch in. And even if it did, the oil pump is driven from the crank, and therefore spins at the same speed as the engine. Plus it has a pressure relief valve to avoid running at too high a pressure. So no! Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 It's not free to do anything, it's connected to the wheels! Plus with no compression you have no force on the pistons to do anything other than run at road speed, or coast down if you put the clutch in. And even if it did, the oil pump is driven from the crank, and therefore spins at the same speed as the engine. Plus it has a pressure relief valve to avoid running at too high a pressure. So no! In the internal combustion engine application, the timing belt connects the crankshaft to the camshaft(s), which in turn controls the opening and closing of the engine's valves. It has custom teeth to turn the camshaft(s) synchronized with the crankshaft and is specifically designed for a particular engine. In some engine designs, the timing belt may also be used to drive other engine components such as the water pump and oil pump. so if the belt snapps then these may also be damaged. if a belt snapps noone knows how they react but i know i certainly dip the clutch imediately. if in any case the engines sensors arnt working correctly (ie, not working as the engine isnt running) and the oil is still circulating, this can cause damage to many seals and may harm other components. and NO not all cars have adequate pressure relief valves, nor are they capable of coping with a sudden 100 maybe plus psi of oil pushing around when it only sits at around 30 and lower in idle or cam belt snapped state. different opinions, different answers, lets agree to disagree Quote Link to comment Share on other sites More sharing options...
trinitom Posted April 3, 2009 Author Share Posted April 3, 2009 It's not free to do anything, it's connected to the wheels! Plus with no compression you have no force on the pistons to do anything other than run at road speed, or coast down if you put the clutch in. And even if it did, the oil pump is driven from the crank, and therefore spins at the same speed as the engine. Plus it has a pressure relief valve to avoid running at too high a pressure. So no! yep i agree with your comment! and i presume the valves will close due to spring pressure preventing the engine to get oxygen, so it just shout off! correct me if I’m wrong! Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 yep i agree with your comment! and i presume the valves will close due to spring pressure preventing the engine to get oxygen, so it just shout off! correct me if I’m wrong! yer the SimonB comment is correct but not fully. we clearly have different opinions yes if the belt snapps then the cam lobes do not spin on the lifters or push on the valves, therefore the valve spring is uncompressed so the valve will remain closed against the head. not allowing fuel or oxygen in so no compression combustion or anything. its my fault for defering off the supra engine, ill close up next time Quote Link to comment Share on other sites More sharing options...
TTRickeh Posted April 3, 2009 Share Posted April 3, 2009 In the internal combustion engine application, the timing belt connects the crankshaft to the camshaft(s), which in turn controls the opening and closing of the engine's valves. You learn something new every day Quote Link to comment Share on other sites More sharing options...
Jake Posted April 3, 2009 Share Posted April 3, 2009 yer the SimonB comment is correct but not fully. You're wrong, Simon is fully correct. if the belt snapps then the cam lobes do not spin on the lifters or push on the valves, therefore the valve spring is uncompressed so the valve will remain closed against the head. not allowing fuel or oxygen in so no compression combustion or anything. So you reckon that after a cam belt snaps all the valve springs are uncompressed? Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 You're wrong, Simon is fully correct. So you reckon that after a cam belt snaps all the valve springs are uncompressed? no im not saying there are all uncompressed. wherever the cam ends up lying is how the valves will sit. however there not oppening and closing anymore thats why the engine wont run ^^^question asked^^ and no hes not fully right. you guys mechanics? Quote Link to comment Share on other sites More sharing options...
Jezz Posted April 3, 2009 Share Posted April 3, 2009 (edited) and no hes not fully right. you guys mechanics? Yes he is, and yes, I am. Cam belt fails at 6000rpm. Cams stop spinning and leave valves in whatever position they were in at the point of failure. Crank can't spin any faster than its spinning at point of failure? Its connectected to the gearbox which is connected to the road via a clutch no? Edited April 3, 2009 by Jezz (see edit history) Quote Link to comment Share on other sites More sharing options...
madmarf Posted April 3, 2009 Share Posted April 3, 2009 Yes he is, and yes, I am. good so am i. right what point are we acctualy disagreing over? Quote Link to comment Share on other sites More sharing options...
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