What happens if you do not change the timing belt at the recommended time ?

[brian777999]

I have just received advice today that when the Toyota Starlet was first released, the recommendation was to change the timing belt at 100,000 km. But over the years Toyota found that the belts lasted much longer so this was was changed to 150,000 km.

 

I am now trying to ascertain what the current situation is. If it is still 150,000 km then I will do nothing because my car has 118,000 km on it.

Edited September 15, 2011 by brian777999

[skipepsi]

Cambelts can have other reasons for failure, age being the most common but anti-freeze oil, petrol or diesel can attack the belt as well. An inspection of the belt may give you more peace of mind. Look for fraying on the edge or tiny cracks in the rubber.

[Adrian Wintle]

I only changed the timing belt twice in the 400K km life of my 1990 Toyota Corolla, at about 120K and 280K (service interval was 100K). I've been a bit more diligent with my Subarus, although the interval is longer for them.

 

The old Subaru 2.2L non-turbo motor (1990s Legacy) was a non-interference engine, so one of my friends just carried a spare belt in the car. When the belt snapped at 260K km, he had the car towed to a garage, had the new belt fitted, and continued on his way (Subaru belts are quite easy to access, so it wasn't that expensive).

 

However, the Mitsubishi 2.0L turbo motor (Galant, Evo 1-3, Eclipse/Talon/Laser) could occasionally jump a tooth, which would bend all the exhaust valves. This was an uncommon, but not rare, occurrence when we were using these motors in rally cars.

 

The amount of damage possible depends on the engine design, but most modern engines are interference designs (for performance/efficiency), so there is a good possibility of significant engine damage if the timing belt fails.

 

Adrian

[34theletterbetweenB&D]

Cambelts can have other reasons for failure, age being the most common but anti-freeze oil, petrol or diesel can attack the belt as well.

Cold starts is another big factor. Some here may remember that non-winterised Japanese cars (Honda Accord was a badly affected model) had a rash of cam belt failures in the winter of about 83 or 84 when the Northern US got an exceptionally cold spell (more like the usual in Alaska). Very simple, the cam belt polymer had effectively set in the cold overnight in vehicles parked outdoors, and 'snap' when first turned over - if the battery had the grunt, sump oil hadn't frozen, doorlocks weren't imnmobilised etc. - it was well cold.

 

Cairns if I remember rightly is a trifle warmer...

[45156]

I was wakened one night to the sound of my next door neighbour's car being brought home on a recovery flatbed. He had suffered a cambelt failure prematurely, and the next morning, the local Ford garage arrived to recover his car to their premises, where it was esconced for several days while decisions were made about whether a rebuild or a new engine would be more economical. I was down there with my own car for an MOT, and the head mechanic showed me the damage - and it was a mess - in the end, the rebuild option worked out at about two grand, and was still cheaper than having the engine replaced. But it was a salutary lesson, and I for one will be having the cambelt in my Fiesta changed at 60000 miles, even though Ford are now saying that it can go on to over 100k - £400 or £2000 - the sums don't add up for me. And there is the danger that you will encounter a disastrous failure when you lest need it - in fact as they often go under load, it is likely that it will be a disastrous failure in a place where you least need it (in the UK, lane 3 of a motorway, perhaps).

 

 

[Horsetan]

....(in the UK, lane 3 of a motorway, perhaps).

 

More likely lane 4 or 5 now that they've widened things!

[Suzie]

If you like the car then it will probably be worth doing at the recommended interval, but if you are paying that sort of money, especially if using pattern parts, make sure you get a guarantee.

 

My experience of changing a timing belt and tensioner on one car ended in disaster when I was supplied with an old stock faulty tensioner by the main dealer, it failed (only causing the belt to jump a tooth fortunately) and they 'very kindly' supplied an identical tensioner under guarantee - but that failed as well with lots of bent valves and a cracked head the result. DIY still saved some money because the complete ready to bolt on replacement head from Ebay only cost £160 - compared to the £400 or so it would have cost to have the belt done at the dealer, but I really do prefer timing chains now!

[skipepsi]

Chains do have their own faults and drawbacks wearing out their tensioner blocks and guides as well as sprockets of course as well as noise but they do give audible warning of their impending demise.

[brian777999]

If your car is fitted with pulleys for belts then surely you cannot fit a chain ?

[edcayton]

If your car is fitted with pulleys for belts then surely you cannot fit a chain ?

 

It was (is?) possible to get a kit to convert the old BMC "A" series engine from chain to belt camshaft drive. It would be a lot more difficult to convert the other way because a chain needs lubrication (and hence an oil-tight cover), plus pretty much all engines are overhead cam now so there are difficulties around the head gasket and camshaft seals and cover.

 

In my somewhat cynical view I regard the adoption of timing belts as a gift to the dealers by the manufacturers so they still have work to do; with modern cars being so reliable and needing less servicing!

 

Ed

[skipepsi]

If your car is fitted with pulleys for belts then surely you cannot fit a chain ?

 

No in general manufacturers decide what they want to use, large diesel engines use a gear train as did some high end Honda motorbikes most other motorbikes use a chain to drive the overhead cams. The porsche we just sold had a similar set up with chain drive from the middle of the crank to the double overhead cams.