pistonbroke Posted September 6, 2011 Author Posted September 6, 2011 Fingers crossed for not more than a couple of valves bent should be around 400 mark But knowing my luck could be double . In either case it would be worth the repair costs (just) as the car is in good nick otherwise QUOTE On the subject of chains, don't get all excited about how extremely reliable it makes a car. The chain on my Merc van (2.0 petrol) snapped at 170,000 causing £1500 worth of damage after regular oil changes from day one! Seems you just cant win Quote
Man On The Clapham Omnibus Posted September 7, 2011 Posted September 7, 2011 Chains tend to rattle like a nut in a biscuit tin before they do any damage, though. Quote
SteveH Posted September 7, 2011 Posted September 7, 2011 Not on the later stuff, a lot of the jumpers that I see sounded fine but maybe got stalled or clumsy gear change and it's game over Quote
hilux Posted September 7, 2011 Posted September 7, 2011 It was 36k, but when I last enquired, was told that ford had changed this to 70k Interesting to know about the chain drive , which engine would that be ? Cam belts are also time related with regard to changes Should be changed every 3 years regardless of mileage as they deteriorate with time. Quote
SteveH Posted September 8, 2011 Posted September 8, 2011 Ten years and up to 150,000 miles on some belts now and they look so strong that you actually believe that they will do it! If anything it is more likely that the pulleys will be the weak point. Quote
Man On The Clapham Omnibus Posted September 8, 2011 Posted September 8, 2011 My pinto engined 1987 Granada service schedule stated that the belt was "for life". Presumably they mean for the life of the engine - when it breaks the engine's stuffed and any warranty ends! Actually the Pinto is a non-clashing engine in standard form. Quote
hilux Posted September 8, 2011 Posted September 8, 2011 Ten years and up to 150,000 miles on some belts now and they look so strong that you actually believe that they will do it! If anything it is more likely that the pulleys will be the weak point. Really??? I didnt know they were that reliable (or longlived) these days - amazing really when you think of what they have to do and the forces applied to the `teeth`(try turning over a modern high compression engine by hand with plugs in ) Quote
Man On The Clapham Omnibus Posted September 9, 2011 Posted September 9, 2011 The cambelt drives only the valvegear, nothing to do with compression surely? Quote
MGF255 Posted September 9, 2011 Posted September 9, 2011 The cambelt drives only the valvegear, nothing to do with compression surely? compression is reliant on valves opening and closing at the right time & not being bent by drive / belt failure , so yes valves & their operating gear are pretty crutial to an engine having good compression . Quote
pistonbroke Posted September 9, 2011 Author Posted September 9, 2011 Motco is correct , the function of cam belt / chain is to apply a turning force to the camshafts , nothing to do with compression . If you were to remove the plugs (zero compression) the force required to rotate the camshafts would be the same Quote
pistonbroke Posted September 9, 2011 Author Posted September 9, 2011 methinks Matt was getting a bit muxed ip Quote
MGF255 Posted September 9, 2011 Posted September 9, 2011 Not really because no "turning force" at the cams during operation on a diesel = bent valves and no compression . Also it`s usually easier & cheaper to have some kind of roadside breakdown cover with any of the many companies offering it so you can at least get the car home and not have to mess about trying to hire trailers etc at short notice or be at the mercy of a local garage`s pricing where you happen to breakdown . Quote
Man On The Clapham Omnibus Posted September 9, 2011 Posted September 9, 2011 QUOTE I didnt know they were that reliable (or longlived) these days - amazing really when you think of what they have to do and the forces applied to the `teeth`(try turning over a modern high compression engine by hand with plugs in It was this statement that I was querying. The torque passing through the cam belt has nothing to do with the engine's compression ratio, only its valve springs' rating and cam drag. At higher speeds there's the inertia factor to consider. I agree with the surprise at the longevity of modern cam belts when the work they have to do is considered. I wish I hadn't started this 'cos it sounds as if I'm being bleedin' awkward! Quote
hilux Posted September 9, 2011 Posted September 9, 2011 ....................I cant be wrong (can I?)...................... .........................its the overall resistance and load thats on the belt - if the crank drives the cams then there must be compression resistance to the crank (lessened if you take out the plugs) What I mean is that if you try and turn an engine over by hand from the crank the (cam) resistance is massive as is the overall resistance (lessened with the plugs out but not by as much as you`d think) Am I mad or am I mad? Quote
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