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The mkiv Supra Owners Club

Catastrophic Water Pump Failure


Kendo11
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Thought you chaps may like to have a look at what happened to me earlier this week.

 

Basically my water pump jammed somehow causing the viscous clutch fan to shear itself straight off the shaft, slicing a belt and obliterating the fan shroud into roughly 1000 pieces.

 

Absolutely no idea what caused it but luckily for some reason I had the foresight to have ordered a new water pump just before Christmas.

 

Luckily I had just made it to the spray shop rather than hurtling down a motorway or something.

 

Answers on a postcard as to what may have caused this.

 

(replacement clutch, belts and other bits on the way to go with the new pump).

 

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attachment.php?attachmentid=216795&stc=1&d=1485985460

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Coolant gets into the bearings through tired seals, bearings heat then seize, inertia sheers off shaft.

 

Or viscous unit is knackered and allowing fan and unit to be out of balance fatiguing shaft over time.

 

Does the pump still turn freely?

 

Relatively freely.

 

I have a new pump, fan clutch and a thousand other bits too.

 

Once the pump is removed are there any markings to show whether it's OEM or not?

 

Any recommended tests to identify the issue in case it's related to anything else?

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Right, I put my glasses on, we have a text book ball bearing seizure failure here. See the heat bluing on the shaft and flange? See where the shaft has failed at the base of the U channel where the balls run? And the granular nature of the break is typical of torsional shear? The bearing partially seized, got MAD hot, seized totally, and inertia span the viscous unit and fan off shearing the shaft at the base of the groove, which was probably red hot at the time. Coolant leakage cooled it and the pump is now free as the bearing is effectively none existent now. A new pump will come with proper studs for the flange rather than the Heath Robinson bolts.

 

 

Check the viscous is neither seized nor too free, has no axial or radial play and is quiet, and it should run again.

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Right, I put my glasses on, we have a text book ball bearing seizure failure here. See the heat bluing on the shaft and flange? See where the shaft has failed at the base of the U channel where the balls run? And the granular nature of the break is typical of torsional shear? The bearing partially seized, got MAD hot, seized totally, and inertia span the viscous unit and fan off shearing the shaft at the base of the groove, which was probably red hot at the time. Coolant leakage cooled it and the pump is now free as the bearing is effectively none existent now. A new pump will come with proper studs for the flange rather than the Heath Robinson bolts.

 

 

Check the viscous is neither seized nor too free, has no axial or radial play and is quiet, and it should run again.

 

Makes sense. New pump does indeed have the correct studs as opposed to bolts. Possibly a bodge in previous ownership somewhere down the line.

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