Timing chains

[Bren]

As an audi s4 is potentially on the shopping list later in the year I thought I would do my homework on any foibles.

 

Like so many cars the timing chain is a potential weakness- I was interested in one car with 77k on an 04 plate, however a full history was five services. Five oil changes in its life.

 

Despite the current generation of engine oils it would appear that worn/broken chains are commonplace - having long and convoluted runs and being lubed with filthy oil (extended service programs)seems to be the cause of the problem.

 

I changed the chain on a twin cam sierra I once owned- it had stretched so much it had destroyed the plastic guides and worn a groove in the aluminium casting - the tensioner was also knackered.

 

Like wise my mate's 2.2 signum, the balancer chain had jumped teeth - the whole lot was replaced, the bits alone cost around £400.

 

Maybe belts are better?

[forddeliveryboy]

Last time I peered inside a modern's engine, I was amazed by the Ratner-like quality of the chain. Admittedly it was a Vauxhall, and the Audi no doubt has a beefier chain - but it's the tensioners and guides which apparently give bother on these. I know owners are suggesting 5k as the oil change limit, given it's an engine out job to replace the chain(s).

 

Perhaps it will all go full circle when people get fed up with massively expensive chain replacement and pushrods will make a reappearance, but with glued together sticks of spaghetti.

[RayMK]

I've had two belted cars fail.  A Hyundai Sonata tensioner broke and derailed the belt.  Fortunately, it was a non interference engine and I was only 100metres from a garage, so all fairly painless and £300 to fix.  My wife's Tipo belt failed, then she tried to start it over and over and over again.  When all the valves had been properly bent and piston crowns battered she phoned me.  That cost £500 to sort out in the late 1990's.  Chains give more warning of failure, and on pushrod engines seem to last for the life of the car i.e. 6 years if its a Ford Escort or an early Vauxhall Victor - due to disolving bodywork.  I still prefer chains.

[Matt]

Perhaps it will all go full circle when people get fed up with massively expensive chain replacement and pushrods will make a reappearance, but with glued together sticks of spaghetti.

 

What is the most modern car sold in the UK with pushrods? Skoda Felicia comes to my mind.

[dollywobbler]

IIRC, the Rover 75 V8's Mustang lump was still a pushrod unit. 

 

Timing chains sadly can and do fail, and are a lot more expensive to replace than belts. Gears FTW.

[Joey spud]

The 1200cc 3 pot VW engine in the Polo,Fabia,Ibiza etc is a bit cack.

 

These things rely on oil pressure to push a hydraulic piston against the chains tensioner assembly and after a few miles they start to suffer with poor oil supply / dirty oil which causes the tensioners piston to stick allowing the now slack chain to jump a few teeth.

 

You come out in the morning try to start your car and it spins over like the plugs are out or runs bit miss fires like a bastard.

 

I was told by a VW tech that they have had them jump teeth in the workshop after they have done an oil / filter change due to there being no oil pressure for the first few seconds of cranking while the freah oil gets around to the filter.

[NorfolkNWeigh]

I only buy work cars with chains and I've never changed one , so I know that BMW and Merc 6 pot Dizzler chains last at least 300,000 miles, on the evidence of my last 4 cars anyway.

I've also got a V6 S-Type with original chain at 220k that doesn't rattle.

 

I think the 2.2 Shit engine is known for chain failiure.nice to see Vauxhall keeping up the quality, a mate had the oil pump fail on his Insignia 2.0 derv last week, he's had it from new and religiously changes the oil every 2 months- waste of time and money as the fecker barely made 200k ,bring back Cavalier 1.7 Isuzus.

[Joey spud]

Ah that reminds me a 59 reg BMW 320d i had cut out at a junction last week.it span over way too fast,code read it and it had a cam sensor fault (no signal gererated).when i looked a bit closer the chain had snapped,thats why it wasn't sending a signal..

 

I googled it up later and the N47 engine is prone to it and opinion is its down to their long oil change intervals and degraded oil quality.

Owners rag them around then just switch them off without letting them idle for a couple of mins to cool the turbo so the oil sits around the turbo bearings getting cooked which turns it to carbon that then gets carried around the engine blocking up things like the little nozzle that sprays oil onto a cam chain.

[forddeliveryboy]

Gears have their problems, and I'm sure the cost accountants could make some new ones up.

 

Get rid of the camshaft altogether, I say.

[dollywobbler]

Gears have their problems, and I'm sure the cost accountants could make some new ones up.

 

Get rid of the camshaft altogether, I say.

 

Can't say I've ever had camshaft drive issues on a 2CV. Do recall someone doing a gear kit for the Tdi but not sure I've ever seen a vehicle with such an engine advertised as having one fitted.

[EssDeeWon]

Regardless of belt or chain if its had prolonged service schedules then I would be giving it a wide birth, with something like an S4.

 

My 75 is about to have its 11th service at 66k, but that doesnt mean the belt cant break next week.

 

Generally speaking chains are better IMHO.

[forddeliveryboy]

Can't say I've ever had camshaft drive issues on a 2CV. Do recall someone doing a gear kit for the Tdi but not sure I've ever seen a vehicle with such an engine advertised as having one fitted.

 

Thought we were talking about overhead camshafts, not ones running right next to the crankshaft living in the sump oil as with a 2cv. In which case the valve gear is referred to as being pushrod operated, not gear driven. Same with some old Landies - pushrods to open the vavles, even though the camshaft is actually linked to the crankshaft by a chain.

 

Even so, 2cvs are known to break the little springs which spring the two halves of the cam gearwheel together, for timing accuracy. Usually on later cars - crap quality bits - and owners using cheap oil which is left in too long.

[Asimo]

 

Someone popped this image in the duff SaaB thread a few weeks ago.

 

Audi V8

 

It would put me off.

[fordperv]

 

I changed the chain on a twin cam sierra I once owned- it had stretched so much it had destroyed the plastic guides and worn a groove in the aluminium casting - the tensioner was also knackered.

 

The chain on mine got changed as a matter of course when the headgasket was replaced because there wasn't a receipt for it getting done, there was very limited stretching in the chain and the guides were like new, shocked the life out of me that did, everything was replaced with new genuine parts for peace of mind.

[Simcat]

Side valve engines with gear driven cam are pure simplicity - and quiet!

[MrBiscuits]

In this age, it is amazing really that we still persist with camshafts and complex mechanical linkages just to open and close the valves at roughly the right time. It's always going to be a single point of failure, not to mention the power lost to drive the whole lot.

 

Since working out the position of the pistons at any given time is relatively simple for modern electronics, it can't be a massive leap for one of the mainstream manufacturers to replace the whole lot with computer controlled solenoids. This would give infinitely variable and accurate timing for better driveability, be cheaper and easier to maintain and no doubt could be made to fail safe without destroying the engine.

[Split_Pin]

Regular oil changes shoud see you ok with a chain. My Corsa is on 90k now with original chain but I have done 5k oil changes since 65k when I got it. Its still quiet, hopefully won't have any problems with it.

 

Chains usually start to chap away long before they or the tensioner fails.

 

He said.

[tooSavvy]

In this age, it is amazing really that we still persist with camshafts and complex mechanical linkages just to open and close the valves at roughly the right time. It's always going to be a single point of failure, not to mention the power lost to drive the whole lot.

 

Since working out the position of the pistons at any given time is relatively simple for modern electronics, it can't be a massive leap for one of the mainstream manufacturers to replace the whole lot with computer controlled solenoids. This would give infinitely variable and accurate timing for better driveability, be cheaper and easier to maintain and no doubt could be made to fail safe without destroying the engine.

F1 wonks here will be point specific here, I'm sure....

 

When Renault brought out their 1500 Trrbo, against the Cossie V8s, I seem to recall a series of DNF cos the Valve 'SOLENOID/ACTUATORS' went west??? They were Pneumatically operated.. ???

 

I'm not sure if all F1 are ellectikkery type now, though.. ????

 

 

TS

[Matt]

Since working out the position of the pistons at any given time is relatively simple for modern electronics, it can't be a massive leap for one of the mainstream manufacturers to replace the whole lot with computer controlled solenoids. This would give infinitely variable and accurate timing for better driveability, be cheaper and easier to maintain and no doubt could be made to fail safe without destroying the engine.

 

Isn't that roughly along the lines of how Fiat's Multiair system works?

[bub2006]

Famous last words

[MrBiscuits]

Isn't that roughly along the lines of how Fiat's Multiair system works?

That's an even trickier one, hydraulic link between the cam and inlet valves, with a solenoid that bleeds off the fluid coupling to shut the valves earlier.

 

Can't imagine how they dreamt that up.

[srad34]

Ah that reminds me a 59 reg BMW 320d i had cut out at a junction last week.it span over way too fast,code read it and it had a cam sensor fault (no signal gererated).when i looked a bit closer the chain had snapped,thats why it wasn't sending a signal..

 

I googled it up later and the N47 engine is prone to it and opinion is its down to their long oil change intervals and degraded oil quality.

Owners rag them around then just switch them off without letting them idle for a couple of mins to cool the turbo so the oil sits around the turbo bearings getting cooked which turns it to carbon that then gets carried around the engine blocking up things like the little nozzle that sprays oil onto a cam chain.

 

The N47 is made worse by having the chain at the back (unlike the 05-07 320d's) so costs a fortune to replace as the engine has to come out to do it

 

I always change oil every 10k regardless...... 

[Bren]

I believe a similar problem with the golf VR6 - chain at the "wrong" end of the engine.

[forddeliveryboy]

At least with the Reggie4 you just cut through the bulkhead when the chain snapped. Much better engineering.

[spike60]

 

This is what a 3.2 Alfa looks like getting the chains done at 40k odd miles. Parts alone were going to be £4500+ from Alfa, buying from Holden who made the block reduced this to £2650. Don't buy a cam chain Alfa with the EML on, it may be because the chain has stretched.

[Parky]

And this is one of the great engines......

 

quite frankly looking at that and other posters KV6 efforts make me realise that inline fours are quite adequate thank you!

[RayMK]

I'm beginning to prefer 3 cylinder 2 strokes.  Those chain runs look like an almighty mess waiting to happen.  I don't like belts either.

[Lacquer Peel]

Alfa chain.jpg

 

This is what a 3.2 Alfa looks like getting the chains done at 40k odd miles. Parts alone were going to be £4500+ from Alfa, buying from Holden who made the block reduced this to £2650. Don't buy a cam chain Alfa with the EML on, it may be because the chain has stretched.

 

£4500 for chains and tensioners?!

[dollywobbler]

Chains usually start to chap away long before they or the tensioner fails.

 

 

This is certainly true of Mitsubishi Delicas. My mate's was making some very odd scuffing noises. I drove it all the way to Rhyl and back like that. We couldn't place where the noise was coming from. Turns out it was the timing chain eating its way out of the casing. It eventually snapped as he was driving to an airport. Handy!

[garethj]

Get rid of the camshaft altogether, I say.

My favourite quote from a journalist road testing a 2 stroke engine: "It goes alright as long as you keep it on the cam"