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flat broke
03-15-2004, 07:34 PM
my 99 2dr 4x4 just started showing very erratic readings on the temp gauge. Today on my way to lunch, the gauge got up to 240+ but there were no other signs of overheating. I got home from work, swapped out the T stat thinking that maybe it stuck. The problem still exists. The temp gauge will move from 190-195 (where it always used to stay) to 220, then sometimes come down to 180, then jump back up to 240. The movement of the needle is smooth, and it takes about 5 seconds to go from 190-240. It will do this whether it is idling, running down the freeway, or cruising at 40. Air temps today were in the 70s.
Any input would be greatly appreciated,
Chris

LakesOnly
03-15-2004, 07:54 PM
What kind of truck?
Is there a bleeder valve in the cooling system that allows air pockets in the cooling system to be bled out?
LO

Danhercules
03-15-2004, 08:21 PM
I am thinkin air too. Is it full?

flat broke
03-15-2004, 09:00 PM
sorry bout that. It,s5.7 a 99 Cheby Tahoe 4x4 dr with a 5.7. How would air have been introduced into the system to begin with?
Chris

Wet Dream
03-15-2004, 09:10 PM
Originally posted by flat broke
sorry bout that. It,s5.7 a 99 Cheby Tahoe 4x4 dr with a 5.7. How would air have been introduced into the system to begin with?
Chris
Dry reservior? :confused: Wait, let me put some emphasis on that. Not the lake, but the "over-flow" tank on the truck, did it go dry for some time?

flat broke
03-15-2004, 09:34 PM
I'm not under the hood too much on this thing, but I've never seen the resevoir empty. If anyone know's how to bleed this bad boy I'll give that a shot. The way the gauge moves the water temp is either fluctuating greatly, or I'm leaning towards a gauge/sender issue. If it's the gauge, I'm phucked cause you gotta replace the whole damn cluster.
Chris

MikeF
03-15-2004, 09:40 PM
Chris,
Does your heater core make water sloshing noize?
Drive your truck to a fairly steep hill (preferably close to where you live so the cooling system does not get hot enough to cause pressure) and point the truck up the hill. Take off the radiator cap and let the engine warm up, turn on the heater and raise the rpm to circulate the air out of the heater core and into the radiator. Refill the radiator and see if the problem continues. That might help.

flat broke
03-15-2004, 10:46 PM
Thanks Mike.
Would a steep driveway do the trick? If so Hacker's place will do the trick.
Thanks,
Chris

Moneypitt
03-15-2004, 11:46 PM
I assume that this has an electric gauge. I would pull the plug of the sender and see if the gauge still acts up. That would indicate a shorted wire. The gauge sees resistance to ground, and the sender is suppose to be the only ground source. Also beware there may be more than 1 sender, like maybe both heads, and the intake. (maybe)........ If you ground the sender wire, the gauge should peg, just for a second to check the gauge...I hope these newer vehicles still use the basics of old........Moneypitt

flat broke
03-16-2004, 06:06 PM
burped the coolant and sure as shizzle there was air in my nizzle. Thanks for the heads up Mike. See you on Sunday in Bako.
Chris

MikeF
03-16-2004, 06:18 PM
:D