question about water pumps

[jackal264]

ok so i'm having heat issues and i'm just wondering about my pump.

i always thought when a pump fails your either going to get a leak at the shaft or the pump will just not flow.

at this point i have checked every thing else but my pump still flows b/c after a few hard runs my temps get really high but do come down slowly when i let it idle. and it's not leaking.

so what i'm asking, is it possible for a water pump to just start becomming less efficient? like can it just start to flow like 30% of what it was before without obvious simptoms like leaks?

[Autobacs]

I don't think so. The only way that would happen is if the vanes broke off or something.

If the shaft's not leaking and you do not have radial play, I would look elsewhere.

I would definitely look at the radiator unless you have a new one. Years of gunk and bent/corroded fins definitely lowers its cooling efficiency.

[knate]

It *can*, but rarely. Typical failure is the seal (leaking out of the weep hole) like you said, or binding/seizing.

However I have pulled out a water pump that was so corroded the vanes were disappearing.. and this was on a 95 KA. It had been leaking out of the weep hole for long enough to leave a nasty corrosion trail and they must have kept refilling with tap water as it would leak out. Probably had been going on for more than a year.

You can pull the belt off and check for play and make sure it spins smoothly. I also had an old factory pump that would intermittently seize (very rarely) and make the belts squeel that I didn't figure out what was happening until it completely seized. So if you're in there and it's old, they are pretty cheap to replace just for future insurance.

[Ben G]

pressure test your system and your radiator cap