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  #1  
Old 07-27-2019, 11:26 AM
jpliddy jpliddy is offline
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Default dayco or gates timing belt!

hi all
as title asks which is the best timing belt to go for as main dealers no longer stock this item all comments most welcome !
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  #2  
Old 07-27-2019, 01:36 PM
v8volvo v8volvo is offline
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Both are good. Continental/ContiTech, Flennor, and other well known brands also all sell a quality product. You will have no issues with any of them, provided they are replaced on the normal required maintenance schedule (60,000 miles/7 years, whichever comes first).

Have you gotten your engine temperature gauge working yet?
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Old 07-28-2019, 08:43 AM
jpliddy jpliddy is offline
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Thank you for your thoughts V8VOLVO . i cant seem to fix the temperature gauge
im thinking now the problem is in the circuit board but where do i start looking ive changed the gauge and the volt stabiliser box on back of dash my friend shorted the coolant probe at front of engine the gauge never moved . but sometimes rarly the needle move to 11 o clock when engine turned on and cold
its a real pain im only a carpenter any guide most helpful regards jim
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Old 10-21-2019, 11:19 AM
clivealive44 clivealive44 is offline
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Hi V8VOLVO,
"(60,000 miles/7 years, whichever comes first)" I was just wondering where you got this info from, as the official Volvo documentation which came with my car says 80,000 miles, or 8 years, which ever comes first (printed in Oct 97)
Thanks, Clive
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Old 10-21-2019, 08:16 PM
v8volvo v8volvo is offline
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Good question. I have thought of those numbers as the right ones for a long enough time now that I cannot remember exactly what source I would need to cite, but it is based on a published figure that I could probably find again. There are various different specifications that are published so you end up having to decide for yourself which one to trust. Sounds like you saw 80k or 8 years for your later model car. Volvo's original spec that they published for the early style diesels sold here in the US was 75k miles IIRC. There are probably others.

As best I can remember, where I saw the 60k/7 year spec quoted was for the old style 2.0L Audi 5 cylinder diesel engines. Those engines use exactly the same timing belt system as the D24 and D24T (and same water pump, idler roller, etc, the whole front end of the engine is perfectly identical in every way). I figured if Audi only trusted these exact same parts for 60k miles, I probably would only trust them that far also, even if Volvo believed an owner who liked to gamble might get a few more miles out of that belt.

Deeper dive into my reasoning on this: when Volvo first introduced these diesel engines, one of the selling points they advertised for them was the idea that they could require much less routine maintenance than the gas engine alternatives. That included very infrequent oil changes according to their original maintenance schedule (which was later updated and made less extreme). The original long oil change interval is known to have caused rapid wear and premature failures in many of these engines before the spec was updated, so they obviously pushed the service schedule beyond what the actual machinery could support in that area. I figured they might have done the same with the TB interval, wanting to publish as optimistic a figure as they could, especially knowing that the TB change would be far more labor and cost intensive for the diesels than for the gas Volvo engine.

Long story short, I suspect that the longer recommended interval for the Volvo application vs the Audi application with the same parts was not an engineering decision but rather a marketing decision. Since the consequences are so severe for a timing belt failure on this type of engine I feel that erring on the side of caution and going with the most conservative recommendations available makes sense.
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  #6  
Old 10-22-2019, 01:44 AM
clivealive44 clivealive44 is offline
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Thanks for the detailed and interesting response.
I was reading an interesting post on a platform called "Quora", from a 30 year time served mechanic on what causes wear to cam belts, and cam chains. There was an interesting reply from a 25 year time served mechanic from the UK who said the following about the effect of the number of cylinders which an engine has on a cam chain - " the main issues as i see them are the increasing use of fewer engine cylinders meaning the time between firing cycles ‘jolting’ the chain is longer and, as a result the chain is jolted harder (3 cylinder engines are pretty much the norm now, where 5–10 years ago the same cars had 4 cylinders) the stop start technology fitted to many cars now puts more strain on the chains, the average UK motorist only does around 10–12k miles (many a lot less) so again, starting/stopping the engine and straining the chain, and the fact that the strain is now transferred into a single (simplex) chain instead of a duplex chain, (probably due to cost cutting) is also adding to the number of failures."

I have a copy of a chapter on the D24 (and D24t, and D24tic) engine from a Haynes Manual on servicing car and light van Diesel engines published about 1992 for professional mechanics. Interestingly, it gives the basic maintenance interval as 6000 miles, or 6 months, which ever comes first. It says "Volvo recommend that the engine oil (but not the filter) be changed at every 3000 miles on all turbocharged engines, and on normally aspirated engines operating under adverse conditions"
It says that the cam belt, pump belt, and idler roller should be replaced at every 12th maintenance interval, which equates to 72,000 miles, or 6 years.

My car was last done in 2014, at 220k miles, I normally get it done every 60k miles or less, it has now done 272k miles, which means it is due next year. I was half considering leaving it for another year, but I will probably get it done next year to be on the safe side. I have a client who is a 30 year time served Volvo mechanic, I'll ask him and see what he thinks.

Last edited by clivealive44; 10-22-2019 at 02:42 AM. Reason: forgot a bit
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  #7  
Old 10-26-2019, 07:13 PM
v8volvo v8volvo is offline
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Good point. It could very well be that the same components would see more stress on an engine with fewer cylinders, and that could play into the difference in the maintenance recommendations, assuming you give Volvo and Audi the benefit of the doubt and allow that the difference may be related to a technical reason and not different sales philosophies.

Related to what you mentioned, I remember reading an engineering study once showing that engines with fewer than 6 cylinders operating at low engine speeds, when analyzed for "instantaneous" torque at different points during the crankshaft's rotation, are observed to have very large amplitude cyclic variations in that instantaneous torque, including significant negative torque at certain crankshaft angles. The graph of torque on the Y-axis with crank angle degrees on the X-axis looked roughly like a sine wave that moved significantly above and below the average. This is apparently even more pronounced in diesel engines due to their higher compression. Engines with more cylinders had much lower amplitude variations in torque, and much smaller maximum negative torque values. Above a certain number of cylinders (it was either 6 or 8) it showed that there is no negative torque at all anywhere during the crank's rotation.

To my recollection that particular study regarded the need for complex dual-mass flywheels to mitigate damaging torsional harmonics being transmitted through the gearbox and drivetrain from large displacement, high output 4-cylinder diesel engines. But obviously all the same cyclic torque variation would be equally present at the other end of the crankshaft, and would be fed into the timing system as well. Since the phenomenon occurs in inverse proportion to the number of cylinders, one could see how the same belt might live an easier life on a smoother running 6 cylinder engine than on a 5 cylinder engine, even though the belt has two extra cam lobes and one extra injection pump lobe to drive on the 6.

Of course it is also worth considering that all of these preventive maintenance recommendations are by necessity only crude generalizations, since there are many more factors that will affect the lifespan of these components than just odometer miles and years of time. For example if an engine is used for a long distance highway commute with a majority of the miles done in top gear, the timing belt will do far fewer revolutions in 60,000 odometer miles than it would if you did the same 60k miles primarily in low speed, city driving with time spent idling in traffic and at stop lights. Seems easy to imagine that the belt on the city driven engine could see double or triple the number of rotations in a given road distance... Number of thermal cycles probably matters too, as well as ambient conditions, etc. So as the saying goes, your mileage may vary ....
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