Hmm my water pump failed again!!!! Could it be the pulley?!?!

[tk-421]

I just notified MikeNST about this issue. Hopefully he'll chime in soon.

[Altitude]

Maybe we can all agree it is the combination of the pulley or belt too tight and the harsh driving?

[1NZYaris1]

Originally Posted by Tamago

if you say so.



the ratio of water pump failures stock vs pulley tells the tale..

Could it be due to people over tightenning the BELTS

[rhino5]

Just a lightweight pulley or an underdrive pulley?

Pulley driven water pumps are really that mysterious, mechanically there's not much to fail. I'd blame shitty casting or belt tension before blaming pulley ratios.

[YarisSedan]

Well to me it just seems very strange within a month the water pump failed. And my original water pump did not fail until after the pulley was installed as well. When i changed the pulley i marked the altenator position with a white out so that it was isntaleld in the exact same position as factory. I am going to go check the tightness of the belt after the water pump was instaleld by the dealer. If it was put on way to tight and compounded with how i drive i would say that would be the cause this time. Or a combination of the pulley and overtightend.

[severous01]

does the oem pulley have a rubber ring in it? a dampner?

if it is, then the NST doesnt have a dampner. every time the pulley hits TDC or BDC you're slamming the pulleys on all devices and as the pulley rotates towards bdc or tdc the pulleys are slowing down. that's what the dampner does....dampen the force of the engine 'bang' to equalize throughout the rotation.

[YarisSedan]

Yeah the factory one has a rubber one in the middle.

[severous01]

there's your problem. the nst pulley is not a dampner. it's just a pulley.

the rubber ring flexes on the bang and flexes back on compression. so................................................ .................................................. .................................................. ......

deal is, the pulleys are actually moving forward and backwards at an extreme rate and that's not designed to do it. the dampner stops it and prevents the bearings from slamming forward and back.

[fmicle]

Originally Posted by Tamago

the ratio of water pump failures stock vs pulley tells the tale..

I beg to differ. This is a typical mistake people make, just because there is a correlation between A and B it doesn't mean A caused B or vice versa.

Let me explain with an example: studies show that households with more books have smarter kids (correlation between books and kids), so a mayor in Illinois thought he'll simply give away free books and make kids smarter. Needless to say, the plan didn't work. Because it's not the number of books that cause the kids to be smart, it's their parents' education, status, emphasis on school, etc. And those families are likely to have more books to begin with. So, there is another parameter C that causes both A and B to go together.

Back to our situation: people with aftermarket pulleys have more water pump failures than the ones driving stock (that's the correlation). So some people incorrectly infer that the pulleys must cause the failure.

Imagine this: people who install aftermarket parts and tune their cars are more likely to drive their cars more aggressively, therefore putting more stress on their parts than those driving stock (grandma, grandpa, uncle Jimmy).

Just remember the basic principle: correlation does not imply causation. For more details check it out on Wikipedia: Correlation does not imply causation

[PHXDEMON]

Originally Posted by fmicle

I beg to differ. This is a typical mistake people make, just because there is a correlation between A and B it doesn't mean A caused B or vice versa.

Let me explain with an example: studies show that households with more books have smarter kids (correlation between books and kids), so a mayor in Illinois thought he'll simply give away free books and make kids smarter. Needless to say, the plan didn't work. Because it's not the number of books that cause the kids to be smart, it's their parents' education, status, emphasis on school, etc. And those families are likely to have more books to begin with. So, there is another parameter C that causes both A and B to go together.

Back to our situation: people with aftermarket pulleys have more water pump failures than the ones driving stock (that's the correlation). So some people incorrectly infer that the pulleys must cause the failure.

Imagine this: people who install aftermarket parts and tune their cars are more likely to drive their cars more aggressively, therefore putting more stress on their parts than those driving stock (grandma, grandpa, uncle Jimmy).

Just remember the basic principle: correlation does not imply causation. For more details check it out on Wikipedia: Correlation does not imply causation

Wisdom

[YarisSedan]

Yeah but even a car driven agreesively shouldnt have parts like this failing at such a early stage. Maybe at higher milage i could understand but this is just unacceptable.

My 89 acura legend with 200k miles was a tank. I drove it like i stole it for 4 years and never gave me any problems. Only thing major was the altenator that went out once and i attribute that to my high powered stereo system.

And this a toyota which is supose to be better than honda is having problems like this at such a early stage seems unacceptable to me. So even if i put the factory pulley back on and still drive the car aggresively that means i will be having to change my water pump every single year?!?

I know its a econo car but come on.

[eddy]

just wondering what is this other pulley you are all talking about.?

[JohnnoEH]

Originally Posted by fmicle

I beg to differ. This is a typical mistake people make, just because there is a correlation between A and B it doesn't mean A caused B or vice versa.

There is another parameter C that causes both A and B to go together.

Back to our situation: people with aftermarket pulleys have more water pump failures than the ones driving stock (that's the correlation). So some people incorrectly infer that the pulleys must cause the failure.

Imagine this: people who install aftermarket parts and tune their cars are more likely to drive their cars more aggressively, therefore putting more stress on their parts than those driving stock (grandma, grandpa, uncle Jimmy).

I was going to write pretty much exactly this, but you beat me to it. So many people jump to quick conclusions without looking at the whole picture.

Originally Posted by severous01

does the oem pulley have a rubber ring in it? a dampner?

if it is, then the NST doesnt have a dampner. every time the pulley hits TDC or BDC you're slamming the pulleys on all devices and as the pulley rotates towards bdc or tdc the pulleys are slowing down. that's what the dampner does....dampen the force of the engine 'bang' to equalize throughout the rotation.

Having said the above, this could be the source of the problem; especially when combined with the more likely/frequent hard driving that a modded car will receive.

[thebarber]

undampended pullies eat water pumps....ask anyone w/ a 2zzge..

[rhino5]

Originally Posted by thebarber

undampended pullies eat water pumps....ask anyone w/ a 2zzge..

I find it hard to swallow that the small change in ability to dampen on the crank pulley with a rubber belt driven system could destroy a waterpump so easily. If I was ambitious I'd look up what the flex per foot of our serpentine belt has and I'd be surprised if it was so ridged that it wouldn't absorb some of this "destructive" torque/vibration.

Not saying that is without a doubt the problem, but I'd be leery that it's the new pulley.

[lilredrocket]

Could it also be that you got a faulty part?

[rhino5]

Originally Posted by lilredrocket

Could it also be that you got a faulty part?

I mentioned this before. Casting metals yields a relatively high chance of poor quality.

[fmicle]

Originally Posted by YarisSedan

Yeah but even a car driven agreesively shouldnt have parts like this failing at such a early stage. Maybe at higher milage i could understand but this is just unacceptable.

My 89 acura legend with 200k miles was a tank. I drove it like i stole it for 4 years and never gave me any problems. Only thing major was the altenator that went out once and i attribute that to my high powered stereo system.

And this a toyota which is supose to be better than honda is having problems like this at such a early stage seems unacceptable to me. So even if i put the factory pulley back on and still drive the car aggresively that means i will be having to change my water pump every single year?!?

I know its a econo car but come on.

I hear you man, I hear you, and I agree it's unacceptable...