Cambelt Tensioner Bearing

As I have said elsewhere, the cam drive bearings at the bottom take a much bigger load and are much smaller single row ball bearings so definitely check those for any play or signs of grease coming past the seals. The tensioner bearings will probably outlive most of us unless used as a daily driver.

 

If that is true why do we see tensioner bearing failures about 10x as often as lower drive bearings?
You have nowhere near the experience required to comment. And your illinformed conclusion shows it.

Just how many decades have you been working on Ferrari belt drive motors day in and day out?

 

While I agree the Hill bearing is a very good piece in the old days we reused tensioner bearings at 30k belt changes when people were really going 30k miles. We found 2 things. The bearings almost never made it 60,000 miles and we routinely disassembled noisy bearings and found the balls and races to be fine visually.

 

On the 4 valve with the bigger bearings I have replaced one set ever unless the motor was out and all apart. On the 2 valve engine it has never been more than an occasional repair.

The early design was shared with the 365 and 512BB with considerably greater work being done and failure was not a high profile problem on them. The biggest problem that design had on V8 or 12 was seal failure causing an oil leak.

I am however referring to cars properly maintained running correct belt tensions.

 

Glad to see you are as cheerful as ever Brian! So what is your recommendation then? You suggest above that the tensioner bearings still look good at 60k miles. I’m not arguing with you but would genuinely like to know your take on this. Are they failing at 60k or just getting noisy? On paper they are well below their dynamic load limits so maybe it is temperature and seal material. Were these the SKF bearings with buna-n seals or the NTN bearings with viton? I removed the seals of my old SKF bearings out of curiosity and there was very little grease inside so I speculated that the seals had failed (no tears but possibly shrinkage?)