Turboman
Mab An Gov
I agree, could have been manufacturing costs were a factor, and the public wouldn't accept the higher costs of a low volume chain set up.
Theoretically they are noisy, but in practice many cars and motorbikes have chain driven engines, and it is not a problem.
When did you last hear a Td5 owner complaining about being deafened by their timing chain?
flat
Well-Known Member
I meant straight cut gears are noisy, chains are okay
Turboman
Mab An Gov
Sorry, misunderstood that.
Afraid it has still not been my experience. The many old gear driven diesels I have owned and worked on did not suffer from timing gear noise, and in fact you would barely hear the gears over the other engine noises.
And, just from memory, BMW diesel engines in cars are gear driven, and they are not known for being noisy.
My own guess would be that the move to belts was driven by manufacturing and assembly costs, just the same as most other changes in the motor industry.
Motor manufacturers exist to make money, much as the engineering purist dislikes that fact.
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flat
Well-Known Member
Sorry, misunderstood that.
Afraid it has still not been my experience. The many old gear driven diesels I have owned and worked on did not suffer from timing gear noise, and in fact you would barely hear the gears over the other engine noises.
And, just from memory, BMW diesel engines in cars are gear driven, and they are not known for being noisy.
My own guess would be that the move to belts was driven by manufacturing and assembley costs, just the same as most other changes in the motor industry.
Motor manufacturers exist to make money, much as the engineering purist dislikes that fact.
I will bow to your wider experience, and yes I suspect your right re: manufacturers
TBH I thought they would have adopted the chain as an option as the hard work was already done, they literally only had to remake 2 drive sprockets an idler and they could have modded an off the shelf tensioner, could have sold at 1/3 cost of gear sets in my opinion.
Still a market with thousands of 300Tdi engines out there in daily use.
Turboman
Mab An Gov
Personally, I agree. I haven't had bad experiences with chain driven engines.
I think the problem with it would be the low volumes. To make good money out of that sort of kit, they want to sell tens or hundreds of thousands of units.
Not that many were straight cut gears and ran helical gear sets, ever land rover adopted helical gear sets in the LT230 to reduce trace mission noise.Sorry, misunderstood that.
Afraid it has still not been my experience. The many old gear driven diesels I have owned and worked on did not suffer from timing gear noise, and in fact you would barely hear the gears over the other engine noises.
And, just from memory, BMW diesel engines in cars are gear driven, and they are not known for being noisy.
My own guess would be that the move to belts was driven by manufacturing and assembly costs, just the same as most other changes in the motor industry.
Motor manufacturers exist to make money, much as the engineering purist dislikes that fact.
Certainly Cummins, Volvo, Ford(agri & industrial) diesels used helical timing gears and it was up until early 2000s Volvo were still running pushrods in their big diesels.
Sting Ray
Well-Known Member
Gears are simple; it's one of the reasons why I retrofitted a gear driven cam engine into my motorbike. Chains need to be tensioned, and tensioners routinely fail, causing wear of the chain guides when the chain isn't under the correct tension. The chains do eventually stretch, contrary to what many say.
Turboman
Mab An Gov
Chains almost never break. Sometimes the tensioners fail, but you hear the rattle, and put a new tensioner on.
Belts, on the other hand, quite often break, especially if they get contaminated with oil.
I know chains are on the whole more reliable. My logic is that a belt change on most vehicles is a simple quick job that doesnt cost a lot of cash. On my old Astra I do the timing belt every year as its a tenner or so for a belt and I can do it in about 15 mins. I have had a few chain driven engines and whilst I like them I'm always paranoid about the tensioners etc. Had to rebuild a vauxhall 2.2 for my brother in law a few years ago (they were well known for tensioner failure) wasn't a fun job
Turboman
Mab An Gov
Wouldn't worry. I have had countless chain driven engines, and helped people with others. My Saab 900 had a chain driven cam, and another chain that drove the gearbox. No issues, remember these are enclosed chains running in oil, not like the exposed chains on a motorbike.
On the other hand, I have sorted out a number of broken belts, most of which caused further engine damage.
A belt change on an Astra is one thing, sometimes on a boat you will have to remove the engine to change the belt, because a fixed bulkhead leaves no clearance to change the belt.
I did actually buy the astra with a broken belt (from contamination like you mentioned above), which luckily was only 1 valve damaged so was a cheap fix. I know most cars will have more expensive parts than this one too.
Glad I don't drive a boat
I did hire a narrowboat for a weeks hol a few years ago and that was good fun, 3cyl lister i think it was.
Glad I don't drive a boat
I did hire a narrowboat for a weeks hol a few years ago and that was good fun, 3cyl lister i think it was.
Turboman
Mab An Gov
I did actually buy the astra with a broken belt (from contamination like you mentioned above), which luckily was only 1 valve damaged so was a cheap fix. I know most cars will have more expensive parts than this one too.
Glad I don't drive a boat
I did hire a narrowboat for a weeks hol a few years ago and that was good fun, 3cyl lister i think it was.
I prefer driving my boat to any road vehicle I have ever driven.
It is a 65 foot narrowboat, and several of my friends have narrowboats with Listers, both twin and triple cylinder.
They are a good engine, but not as good as my Beta Kubotas, both all gear driven.
I'm also not convinced about timing gears being noisy, got 4 old tractors at my parents place and I dont think there is any noise from gears. I suppose the low operating speed of these engines would be a factor compared to a modern diesel car that can do 5000rpm
jamesmartin
Well-Known Member
its a fact the tdi timing gear kits were it was a common complaint at the time
Shame, I'd have liked a lower maintenance version.
Are timing gears always straight cut or did some engines have helical?
Turboman
Mab An Gov
I would guess that was due to poor design of that particular set-up.
I haven't found tractors to be noisy either, or the gear driven engines on boats. And, as i posted earlier, I have a feeling BMW engines are gear driven.
jamesmartin
Well-Known Member
helical a std, it might have jad something to do with the size of the timing chest large for gears as it was designed to accommodate a belt
