Steve W Posted May 12, 2002 Share Posted May 12, 2002 AND ANOTHER QUERY . . ? ? How many of you have actually had a Timing/Cam' Belt break ? ? At what mileage/age did it go ? ? OR... How many miles/age on same belt ? ? I KNOW THE "BOOK" WILL GIVE AGE/MILE LIMITS BUT THESE ARE SOMETIMES GROSSLY OPTIMISTIC AND SOMETIMES GROSSLY PESSIMISTIC. [ Generally Peugeot's seem to go on 'forever' on same belt, whereas Ford 1.8D seem to break just as you leave the garage after having it (AND all the pulleys! ) changed ] Steve . . . Link to comment Share on other sites More sharing options...
Rob Posted May 13, 2002 Share Posted May 13, 2002 60,000 miles/100,000 km is the life expectancy of the factory fitted belt, which I think, coincides with the old "C" service. If you're getting close then I advise changing it. 24 valves hitting 6 pistons is a lot of money What was wrong with timing chains eh? Link to comment Share on other sites More sharing options...
Guest Martin F Posted May 13, 2002 Share Posted May 13, 2002 The 2JZ is a non-interference engine. Link to comment Share on other sites More sharing options...
MONKEYmark Posted May 13, 2002 Share Posted May 13, 2002 hi i am at 55 thousand miles on my car and was wanting a cambelt change to be safe.so i thought i would get some cams and cam gears at the same time.kill 2 birds with one stone so to speak. hoping the cams make a difference to midrange speed i went for hks 264 in and 264 ex and hks cam gears an engineer at work was telling me about the ford sierra there was a lad had a 1.6l and his cambelt went. the engineer told me that if you start your engine on a 1.6l it fooks engine. but the 1.8l has some room so if you start it it dont cause damage to engine. i would have thought the supra would be the same.does anyone know? thanks for any info have fun Link to comment Share on other sites More sharing options...
Steve W Posted May 13, 2002 Author Share Posted May 13, 2002 NOT QUITE RIGHT... The OLD Ford 1.6 and 2.0 OHC/'Pinto' engines (Sierra/Capri/Cortina) don't damage any valves if belt goes. I KNOW 'cos I had an old mkIII Cortina and the belt went at ~60mph and after I cruised to a stop I turned it OVER + OVER + OVER before thinking "OOOHH wonder if it's the belt ?" Not sure about OHC 1.8 - I'll check. (very few OF them though) All the CVH engines (1.6, 1.4, 1.3 and 'Yankee'1.8 [different type of CVH altogether] ) bend valves when belt goes. In fact the Ford Pinto is one of the only engines we EVER see where valves don't bend with belt failure. Martin, are you SURE the valves won't touch on a 2JZ ? (VERY NICE NEWS if they don't - OBVIOUSLY) Link to comment Share on other sites More sharing options...
Matt Harwood Posted May 13, 2002 Share Posted May 13, 2002 I believe Toyota recommend 60,000 or every 5 years. Mines due now due the age thing... Only done 43,000 but never been changed. I know its already been mentioned, but... Martin, are you sure??? Link to comment Share on other sites More sharing options...
Guest Martin F Posted May 13, 2002 Share Posted May 13, 2002 Yes very sure. (But see disclaimer below) Interesting comment about the Pinto engine. If i remember rightly one of them does bend valves and the other doesn't. i.e. 2.0 will bend valves but 1.6 won't; or maybe the other way around. Maybe the HC version of the Pinto had different clearences. Link to comment Share on other sites More sharing options...
Matt Harwood Posted May 14, 2002 Share Posted May 14, 2002 I had one go on a mk2 Escort RS2000 with no problems. Feel happier about the fact that my Supra belts overdue!!! Link to comment Share on other sites More sharing options...
Steve W Posted May 14, 2002 Author Share Posted May 14, 2002 There's also an 'E-Max' 1.6 Pinto. Which is a higher compression 1.6 based on the 2.0 block (I think ? ). It was Fords attempt to produce an 'economical' Pinto. [ It didn't work too well 'cos the 2.0 was always just as economical as the 1.6 - it's the old "too-small-for-weight=LESS-economy" type thing . . . mmmmmm... perhaps an 8 litre Supra would be MORE economical = Twin Turbo Viper ? (or maybe NOT, ) ] ps. sorry about the messy 'paragraphing', it's the message-edit-box, throws me completely (NOT hard to do ! ) Link to comment Share on other sites More sharing options...
Digsy Posted May 14, 2002 Share Posted May 14, 2002 Originally posted by Martin F The 2JZ is a non-interference engine. Hi Martin, Don't want to sound like I'm disagreeing with you, but this knocked my socks off! Non-interference engines (free running engines as I know them) are getting very thin on the ground, especially high-performance ones. Are you referring to the attached blurb from MKIV.com (from the engine technical description)? If so, then I wouldn't take this alone as gospel that the J2Z is free-running. Its common for an engine to have valve pockets in the top of the piston, and they may only have been designed to provide clearance at the normal valve timing, or thereabouts. The TT with its lower compression ratio might get away with it, but I'm wondering about the NA engine. If you have other evidence, then ignore my ramblings! Link to comment Share on other sites More sharing options...
Guest Martin F Posted May 14, 2002 Share Posted May 14, 2002 Originally posted by Darren Blake Hi Martin, Its common for an engine to have valve pockets in the top of the piston, and they may only have been designed to provide clearance at the normal valve timing, or thereabouts. Oh no this is exactly the argument i read when finding the non-interference info. It doesn't matter what the timing is, if the engine is non-interference it is non-interference. If you disconnect the cam and the crank and turn them with a spanner there should never be a point on the reveloution where the valves or the piston meet, regardless of their position in relation to each other. Make sense ya ? I read a detailed argument and the response from those that have had the engine in pieces was a resounding 'non-interference'. Admittedly i can not remember 100% if this also applied to the NA, but something makes me think it did. Link to comment Share on other sites More sharing options...
Digsy Posted May 14, 2002 Share Posted May 14, 2002 Just checking I designed the valve pockets in the Opel C16XE pistons (the 16v Corsa engine - I'm a Nova boy at heart) when I was a student on work placement, and that engine was definitely not free-running, so valve pockets do not necessarily a non-interference engine make. But of course I have to bow to those who have actually taken the 2JZ engine apart and tried it for real. Excellent news for all of us, I think, especially the tuners! Link to comment Share on other sites More sharing options...
Steve W Posted May 15, 2002 Author Share Posted May 15, 2002 You don't actually have to take it apart of course... You can (and we DO) just turn the engine over (by HAND) on the crank pulley - with no belt on. IF it's 'non-interference' it will "NOT-INTERFER" . . ? ! ? Of course, it's only the engine-builder who does it at our place = he knows what he's doing ( ? ) (to check valve timing/ for ALREADY bent valves etc.) NO, it doesn't hurt/bend valves, IF you know what you're doing. WHO'S THE BRAVE SOUL WHO'S GONNA' TRY IT THEN ? ? ? Only joking... I'd rather wait and find out ! ! [ any way - all academical - I AM going to get it changed for peace of mind - it could go middle of nowhere/Sunday night/ AA on strike etc.] doh ! Sorry Martin..... Just realised you said exactly the same as above... Yours.... Dumbo.... Link to comment Share on other sites More sharing options...
Rob Posted May 15, 2002 Share Posted May 15, 2002 So what you're saying is...if a cambelt snaps under duress, thats it. Thats all the damage that will occur. Sounds like a marvellous piece of design work. Must be a downside though? Link to comment Share on other sites More sharing options...
Digsy Posted May 16, 2002 Share Posted May 16, 2002 Yes, there are downsides. If you have big valve pockets then it gets harder to get a specific compression ratio. If you try to raise the piston crown to increase the ratio, then the pockets have to get deeper so one tends to counteract the other. Also, badly designed poskets can create small "peaks" on the piston crown. These peaks will heat up really fast compered to the rest of the piston, and can cause detonation because they will act as ignition sources if they get hot enough. Finally, the crevice volumes (areas which it is difficult for the flame to get into) in the piston will increase, thereby increasing HC emissions. All of these will be engineered out during development so they shouldn't really cause problems in the field. Just makes life hard for us Engineers Just to labour the point about interference V non-interference a little, the way to check for it is to set a piston at TDC and rotate the camshafts through 360 degrees, feeling for contact. If you try to do it the "other way" - set the valves at max opening and rotate the crank, you might miss the fact that the valve head tracks back and forth across the piston crown as well as decending into it. If the valves do not contact the pistons with this test, then the engine is 100% non-interference (free running). Of course, with the cylinder head ON, you will have no idea of how much the valves are missing the pistons by. As a guide the minimum clearance between valve head and piston crown should be 10% of the maximum valve lift. Link to comment Share on other sites More sharing options...
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