Failure Analysis: Toyota V6 Timing Belt Failure

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Originally Posted By: sleddriver
Originally Posted By: 02SE
It was clearly severely neglected. But to your claim of coolant lubing the water pump bearing. That is simply wrong. Modern water pumps have sealed, lubricated spindle bearings. If coolant (or the rust laden acidic mess coursing through the cooling system in this case) reaches one or both of these bearings, that means a seal has failed. Once a seal fails, contamination will destroy the bearing(s) in short order.
Fair enough.

I thought they were completely sealed. However read something recently from Aisin that stated not to ever turn a WP rotor before installation. Thought that odd. Never heard of that before. So I concluded it might have something to do with needing coolant.

Obviously the seals, then the bearing failed on this one. Pure neglect.


You are right about Aisin pumps. You can google and read the Aisin warning.
 
Originally Posted By: artbuc
Originally Posted By: sleddriver
Originally Posted By: 02SE
It was clearly severely neglected. But to your claim of coolant lubing the water pump bearing. That is simply wrong. Modern water pumps have sealed, lubricated spindle bearings. If coolant (or the rust laden acidic mess coursing through the cooling system in this case) reaches one or both of these bearings, that means a seal has failed. Once a seal fails, contamination will destroy the bearing(s) in short order.
Fair enough.

I thought they were completely sealed. However read something recently from Aisin that stated not to ever turn a WP rotor before installation. Thought that odd. Never heard of that before. So I concluded it might have something to do with needing coolant.

Obviously the seals, then the bearing failed on this one. Pure neglect.


You are right about Aisin pumps. You can google and read the Aisin warning.


As a former Master Tech, I've installed too many water pumps, including Aisin's, to count. The warning for Aisin water pumps is in regards to needing a layer of water between the halves of carbon and ceramic seal, otherwise damage to the seal could result. There are detailed instructions on how to submerge and prelube JUST the seal in water, prior to installation. There is also a warning NOT to submerge the weep hole in water.

The bearing seal is lubricated by coolant, NOT the bearing(s).
 
Originally Posted By: 02SE
The bearing seal is lubricated by coolant, NOT the bearing(s).


Right, as with all mechanical seals. I thought we were talking about seal failures which could lead to a bearing failure?
 
Originally Posted By: artbuc
Originally Posted By: 02SE
The bearing seal is lubricated by coolant, NOT the bearing(s).


Right, as with all mechanical seals. I thought we were talking about seal failures which could lead to a bearing failure?


We are.

But if you read back through the thread, 'Sleddriver' was under the mistaken impression that water pump bearings themselves were lubricated by coolant.
 
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