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Vehicle Tensioner Pulley Bearings.

Hello All,


my vehicle has tensioner pulleys to tension the two main timing belts, the first is a balancing shaft belt, the second the main camshaft timing belt. I recently renewed the belts and tensioners and water pump. The tensioner pulleys have ball bearings and these can wear over time or the lubrication grease gets dry or contaminated with dirt. So they get renewed. The old ones had metal ball cages.


I bought some new tensioners for a second twin vehicle and the bearings have plastic ball cages. Now I am worried that they are not so good in the hot envirinment next to a diesel engine. Also the essential component may fail causing the timing belt to break and the engine become seriously damaged.


The tensioner pulley bearings get a lot of use, as they are rotating all the time the engine in running and can accumulate high mileage.


Should I dismiss the plastic cage type and search for metal cage type tensioner bearing pulleys?


Thanks,


Z.
  • Are the new bearings a type recommended by the engine maker, or just something the local bearing shop reckons is the right size? - if the former I'd expect to see a high temperature oil resisting plastic and not worry, if the latter, in your shoes I'd be looking to exchange, its not something to gamble with.


    Some plastics are indeed very good, and are designed for service in near boiling oil  Others are not.  for a laugh compare the temperature ranges for PEEK and Acetyl on this datasheet.  Problem is you won't know what plastic you have without more info..