A while back, I did a cambelt on an engine and in the process, sent a pic across to a friend in the parts industry overseas. I was somewhat surprised to be told that the belt I had was a "48,000 mile belt but the new ones are a 72,000" which was explained to me as the materials they're made from these days and that the belt I had on the car (supposedly changed as routine service) had been out of production for at least 8 years.
We often get new owners enquiring about how and when to change a cambelt and in the process also often hear theories about cambelts "skipping a tooth" or recently an owner who was told by a repairer that some belts whine when changed; neither are practical and the only ones that whine are the ones set too tight. It is usually always suggested by the manuals (which remember are now possibly best part of 20 years old so will contain info referring to older style belts) that the belts need "retensioning" after a short period.
I've just done a cambelt on an 8 valve PSA engine and noticed a bit of interesting info printed on the box the belt came in that I feel is relevant to anyone wanting to do a belt change.
1st Generation:
(NEO) = Neoprene, fibre glass cords and nylon tooth facing.
2nn Generation:
(HTN) = High-Temperature Neoprene, fibre glass cords and nylon tooth facing.
3rd Generation:
(HSN) = Highly Saturated Nitrile. Aramid fibre or fibreglass cords and non stretch nylon facing at higher temperatures with greater horsepower.
A graph showing the heat resistence comparison is also interesting with Gen 1 showing at 105 degrees C which is increased to 130 for the Generation 3 belt.
Having done at least 3 cars in recent months that have been up on mileage for a cambelt change, past the recommended intervals mileage and age wise and then discovered belts that seemed to have never been off the car, (particularly the instance of the long out of production belt) it has to be wondered if some of the service people are using this higher specs belt as a reason to not do a belt change but to "take a punt" that it will go long enough for the current owner to get rid of the car before there's a catastrophe; maybe I'm just a bit cynical based on my own recent findings. It may also explain why the 16V engines were supposedly prone to snapped cambelts and how these days we rarely ever hear of a belt snapping in comparison to back when they were much younger.
I'm not suggesting that a new belt bearing the HSN specs is the be all to end all and that one cambelt change will see the rest of your days of ownership out, but I do believe that if cambelts are genuinely changed at the recommended intervals, using these newer high spec belts, then chances are you may never have to wear a busted engine due to failure; it lowers the risk considerably.
It must also bring into question a belt whirring or whining after change being a a very risky proposition as having now a "non stretching nylon facing" is an advantage in a properly set up cambelt situation but walking through a minefield if overtightened. The upside of course is that being a non stretching type means it should really be a case of once it's set it should be left rather than risk stressing the non stretch facing.
If nothing else, a well fitted belt of Gen 3 specs should give any owner of a car with an interference engine a bit of peace of mind.
Alan S
We often get new owners enquiring about how and when to change a cambelt and in the process also often hear theories about cambelts "skipping a tooth" or recently an owner who was told by a repairer that some belts whine when changed; neither are practical and the only ones that whine are the ones set too tight. It is usually always suggested by the manuals (which remember are now possibly best part of 20 years old so will contain info referring to older style belts) that the belts need "retensioning" after a short period.
I've just done a cambelt on an 8 valve PSA engine and noticed a bit of interesting info printed on the box the belt came in that I feel is relevant to anyone wanting to do a belt change.
1st Generation:
(NEO) = Neoprene, fibre glass cords and nylon tooth facing.
2nn Generation:
(HTN) = High-Temperature Neoprene, fibre glass cords and nylon tooth facing.
3rd Generation:
(HSN) = Highly Saturated Nitrile. Aramid fibre or fibreglass cords and non stretch nylon facing at higher temperatures with greater horsepower.
A graph showing the heat resistence comparison is also interesting with Gen 1 showing at 105 degrees C which is increased to 130 for the Generation 3 belt.
Having done at least 3 cars in recent months that have been up on mileage for a cambelt change, past the recommended intervals mileage and age wise and then discovered belts that seemed to have never been off the car, (particularly the instance of the long out of production belt) it has to be wondered if some of the service people are using this higher specs belt as a reason to not do a belt change but to "take a punt" that it will go long enough for the current owner to get rid of the car before there's a catastrophe; maybe I'm just a bit cynical based on my own recent findings. It may also explain why the 16V engines were supposedly prone to snapped cambelts and how these days we rarely ever hear of a belt snapping in comparison to back when they were much younger.
I'm not suggesting that a new belt bearing the HSN specs is the be all to end all and that one cambelt change will see the rest of your days of ownership out, but I do believe that if cambelts are genuinely changed at the recommended intervals, using these newer high spec belts, then chances are you may never have to wear a busted engine due to failure; it lowers the risk considerably.
It must also bring into question a belt whirring or whining after change being a a very risky proposition as having now a "non stretching nylon facing" is an advantage in a properly set up cambelt situation but walking through a minefield if overtightened. The upside of course is that being a non stretching type means it should really be a case of once it's set it should be left rather than risk stressing the non stretch facing.
If nothing else, a well fitted belt of Gen 3 specs should give any owner of a car with an interference engine a bit of peace of mind.
Alan S
