What happens when water pumps go bad?
07-16-2007, 10:19 PM
#12
Originally Posted by thunder550
Reason I'm asking....with the clutch fan back on and a 180* t-stat my truck cruises between 200 and 210 and idles as high as 225*. My water pump has about 100k miles on it. I just picked up a new one today, but does anyone know what happens when one goes bad? Do the gradually lose the ability to efficiently pump water? Sucks, because I have a brand new 180* stat in there, and the new water pump is the 05+ style, so I have to buy ANOTHER thermostat.
My other bet would be an air pocket -- they can be a real pita...
What was ambient temp today? Was it a 115er?
07-16-2007, 10:21 PM
#13
Between 109 and 112 depending on the part of town I was in. I got a tip from a member on GMFS to try and vent the coolant crossover tube between the heads since it's the highest point on the engine. I'll give that a shot and see if I can bleed any more air out of it.
07-17-2007, 07:39 AM
#14
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Thats what I did last time, when you open the surge tank the fluid will start to flow out of the tube. check out your heater hose they seem to be the highest point. I'm going to try and find a tee fitting I can further purge up top. Do you know if the coolant is always flowing through the heater? I think the air is getting to that point and when I punch it the flow must increase and force the air in to the engine.
07-17-2007, 12:52 PM
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i have seen this a lot. take off the small hose between the passenger side radiator and the top of the coolant tank. there is an orfice in the radiator. i have seen these get stopped up and cause overheating issues. take an air hose and blow it back into the radiator.
07-17-2007, 03:27 PM
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Originally Posted by jconner111
run the vehicle to full hot at idle with the resevoir cap off?
I'm willing to bet it's air. I've seen the same thing too. If I refill it with the cap off the fill tank and let it get up to temp, all seems to be well. Overtime a little coolant will boil off and I start to see the symptoms you're describing, except it only shoots up to 210 in traffic. Almost instantly.
I'll get moving and it won't make much difference. I burp the system and refill it and I'm good to go for a long time. 
07-17-2007, 03:47 PM
#19
Maybe yall can help me as well mine will randomly get hot sitting still or slowly moving but when you get going it will drop quickly and I have seen as high as 258 and that was on a EFI log. Just started doing it about a month ago and like a said sometimes it does it and sometimes it don't. Sorry for the high jack just thought maybe someone could help both of us.
07-17-2007, 06:08 PM
#20
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Had an incident once with my gn. Pump seal took a dump on me on the way to work. Limped it home, went to the local parts store and bought a pump and put it on (friggin' intercooler had to come off) and figured I was done with it.
Couple days later I'm toolin' down the interstate when I look down at the gauge and see that I'm running 240+. WTF!? When I'd slow down it would cool down, but be right back up there if I put anything resembling a load on it.
So I limp back home and start checking it out. At first blush everything's fine. I cool it down, then start it up with the cap off and wait for it to warm up. It was flowing water, but not much. Tear the whole mess back down. Turns out the impeller would spin on the shaft. It wasn't compeletely loose, and wouldn't back in or out, so it would flow just enough to keep it from complete meltdown.
Of course this would have to be Sunday, and the place I got that pump from wasn't open. Had to have something since it was my DD at the time. Had to get one from PepBoys
But the most fun was when I took the screwed pump back to the original store. When they started in on the "why do you want to return it" crap I just held the pump by the fan mount and flicked the impeller with my finger. Suddenly you could hear a pin drop in there... 
Couple days later I'm toolin' down the interstate when I look down at the gauge and see that I'm running 240+. WTF!? When I'd slow down it would cool down, but be right back up there if I put anything resembling a load on it.
So I limp back home and start checking it out. At first blush everything's fine. I cool it down, then start it up with the cap off and wait for it to warm up. It was flowing water, but not much. Tear the whole mess back down. Turns out the impeller would spin on the shaft. It wasn't compeletely loose, and wouldn't back in or out, so it would flow just enough to keep it from complete meltdown.
Of course this would have to be Sunday, and the place I got that pump from wasn't open. Had to have something since it was my DD at the time. Had to get one from PepBoys
But the most fun was when I took the screwed pump back to the original store. When they started in on the "why do you want to return it" crap I just held the pump by the fan mount and flicked the impeller with my finger. Suddenly you could hear a pin drop in there...
