Cam belts

[Deleted]

I had to change the cam belt and water pump on my Skoda Octavia last Nov as the pump was failing. Not best pleased as it had only done 45k but it was 6 years old. 

One of our other Skodas is nearly 7 years old, but mileage is lowish at 45k. They recommend 100k or 5 years for a replacement. The main dealership did not mention it needed replacing until I asked.

Is it false economy to delay the replacement? 

[andy]

Is it a cam belt or accessory drive belt? A cam belt failing could cause catastrophic engine damage but an accessory drive belt a bit less of a worry....if it looks OK and doesn't squeal I'd leave it. Sometimes new parts fail quickly.

I'd have thought the cams would be chain driven internally and the belt on the outside does things like the coolant pump to prevent overheating, power steering pump, alternator and air conditioning compressor.

[davem399]

My SEAT has the 1.9 VW tdi engine.  The cambelt is not a chain timing belt, but the rubbery type of belt and it also drives the water pump.  When I’ve had mine changed, the garage also do the water pump at the same time.

[John Farrell]

Check if your engine is an "interference engine" - do the valves and the pistons occupy the same cylinder space at different stages of the compression cycle - if yes, the engine can be damaged if the timing belt breaks. Change it.

[JohnY]

Jan 30, 2023 18:11:20 GMT andy said:

Is it a cam belt or accessory drive belt? A cam belt failing could cause catastrophic engine damage but an accessory drive belt a bit less of a worry....if it looks OK and doesn't squeal I'd leave it. Sometimes new parts fail quickly.

I'd have thought the cams would be chain driven internally and the belt on the outside does things like the coolant pump to prevent overheating, power steering pump, alternator and air conditioning compressor.

A sane user might well expect so. Chain driven camshafts become very noisy before the chain brakes. Gear driven cam shafts are out of fashion. Squishy timing belts are the norm.

The most efficient engines are interference. Suck is enhanced by a turbocharger; squeeze is enhanced by very small clearances between the piston going up and the cylinder head with its sticky out bits like valves; bang is not a detonation but a smooth burning as fuel is injected directly into the cylinder; blow is slightly impeded by the driving of the turbo charger but careful tuning by the designers minimises that effect.

A broken timing belt destroys the valves, piston, cylinder head and causes much damage to the cylinder bore. I wouldn't chance missing an advisable timing belt change.

[dreampolice]

My VW Transporter van will be 4 years old in July. At 4 years VW state the cam belt should be changed. As I have an extended warranty and service plan I really need to follow their advice. They charge £450 I believe for that and the water pump. If I ignore it and it breaks I'm stuffed.

[gray1720]

Jan 30, 2023 18:37:51 GMT John Farrell said:

Check if your engine is an "interference engine" - do the valves and the pistons occupy the same cylinder space at different stages of the compression cycle - if yes, the engine can be damaged if the timing belt breaks. Change it.

Having had a cambelt break I would rephrase that a bit:

if yes, the engine will be f***ed if the timing belt breaks.

[JohnY]

Jan 30, 2023 19:34:55 GMT gray1720 said:

Jan 30, 2023 18:37:51 GMT John Farrell said:

Check if your engine is an "interference engine" - do the valves and the pistons occupy the same cylinder space at different stages of the compression cycle - if yes, the engine can be damaged if the timing belt breaks. Change it.

Having had a cambelt break I would rephrase that a bit:

if yes, the engine will be f***ed if the timing belt breaks.

John F and I were trying to be polite. You are of course correct in your prognosis.

[davem399]

Jan 30, 2023 19:34:55 GMT gray1720 said:

Jan 30, 2023 18:37:51 GMT John Farrell said:

Check if your engine is an "interference engine" - do the valves and the pistons occupy the same cylinder space at different stages of the compression cycle - if yes, the engine can be damaged if the timing belt breaks. Change it.

Having had a cambelt break I would rephrase that a bit:

if yes, the engine will be f***ed if the timing belt breaks.

We had an old Fiat Punto which snapped its cambelt. It had Fiat’s FIRE engine in which the valves do not hit the pistons if the cambelt snaps.  For the price of a new belt at £9 and a few hours under the bonnet, I was able to get it back on the road.

[geoffr]

I gather that belts are preferred because they are quieter. Personally I would always go for a chain, at least you get some warning of impending failure. Unfortunately it appears the trend is to dumb down and hide useful information from the driver. The Jag I had some years back was devoid of dip stick, coolant temperature, boost gauge and simplicity. The last electric car I drove was more computer game than driving experience. I am sure the manufacturers want one to just let them do what they deem necessary every 12 months rather than DIY.

[nimbus]

The Octavia is not a safe engine, a stripped or snapped cambelt (timing belt) causes major damage, never delay the job, it is not unknown for it to fail early. On occasions a seized water pump can cause the failure, which is the reason for changing that, the tensioner and rollers at the same time. It's a job any competent garage can do, it's not necessary to be ripped off by a franchised dealer.

At 7 yrs/45k it is overdue, I had one fail on a Cavalier with a full stamped service book including the service at the time the belt was due, clearly it had not been done, with or without the knowledge of the original owner. Fortunately on the engine fitted in that car it did not cause any further damage.

[nimbus]

Feb 3, 2023 22:11:17 GMT geoffr said:

I gather that belts are preferred because they are quieter. Personally I would always go for a chain, at least you get some warning of impending failure. Unfortunately it appears the trend is to dumb down and hide useful information from the driver. The Jag I had some years back was devoid of dip stick, coolant temperature, boost gauge and simplicity. The last electric car I drove was more computer game than driving experience. I am sure the manufacturers want one to just let them do what they deem necessary every 12 months rather than DIY.

Belts are indeed quieter, they are also easier to change. VAG returned to using belts on one engine after frequent chain breakages. Chains on some BMW engines can fail with little or no warning.

Manufacturers do try and tell us as little as possible as well as making what should be simple jobs such as changing bulbs difficult. The dip beam headlamp bulb on my Alfa Romeo Giulietta is ideal for somebody with 6 inch fingers the thickness of a pencil, I remember becoming very angry changing that part on a Ford Mondeo as access was very tight and they used to expire every few months.

[Deleted]

Thanks for all the replies. Not changing the cam belt is not a wise move. We need to decide if we are selling the car in the very near future.

[John Farrell]

The last "european" car I had was a Ford Sierra station wagon, back in the 1990s. The 5 cars since then have been Japanese - used imported cars. None have required serious engine maintenance, although we did have the cambelt changed on the Toyota Corolla we bought in 2007, although it had done less than 10,000km, it was 11 years old.

[zx9]

Feb 3, 2023 23:41:44 GMT @bazarchie said:

Thanks for all the replies. Not changing the cam belt is not a wise move. We need to decide if we are selling the car in the very near future.

Depending on age and value of the car, selling it with new cam belt and water pump could make it more attractive to potential buyers.