Coolant temp gauge gone crazy!

[ShadetreeSHOguy]

hey guys, i hope yall can help. It all started yesterday when i was on my way home from work, i llooked down at my gauge and it was all the way between the O and theh N so i pulled off the road and turned my car off, and looked under the hood. There were NO sympoms of overheating the engine temp "felt" normal. Then i pulled the radiator cap off (i know i know you're not supposed to) and nothing sprayed!!, the fluid was right at the top, and it wasnt even scalding hot!!, so after about 2 minutes i cranked it back up and the gauge was between the M and the A, about 30 seconds later it was almost to the N again!!!! i proceded to bump the throttle a little and it droped down to the R. and it proceded to do it again. its parked now for fear of head gasket failure, any ideas on what i should do? btw, in the llast 4 months ive replaced, the coolant temp sendor, thermostat, and the radiator(last week), heeeeeelp!!, thanks!

Chris

 

[Slo-Sho]

How long was the engine running when you noticed the "karazayness" of the gauge?

 

[ShadetreeSHOguy]

well, i just had to drive to town today, it goes from the very cold (pegged on the bottom), to the N in about 3 minutes,

 

[n8rsk8r]

how long has it been since you changed the fluid? Also, get some Water Wetter, the stuff is great, it helps stabilize your coolant. Take care, hope you get it figured out

EDIT: nevermind, just reread your post, try the water wetter, and I really don't know what to tell you, I DO know that factory gauges are a HUGE joke, maybe grab up an aftermarket temp gauge

 

[rangerj]

When you refilled the system with coolant did you purge all of the air?
Air pockets will cause the hot spots and spike in the gauge if the hot bubble gets around the sending unit.

Put the heater in the on position, remove the radiator cap, and transfer a few inches of coolant to the overflow bottle. Then let the engine run up to operating temperature so that the thermostat will open and the fluid will circulate. Usuall after the thermostat has opened and closed three or four times the air will be eliminated.

That should resolve your temperature spikes and the gauge should return to acting NORMAL. rangerj

 

[ShadetreeSHOguy]

thanks for ya'lls help, my dad thought it was something electrical, turns out the rear ground that attaches to the intake manifold , that nut had gotten loose and it was shorting out making my gauge go nut, thanks guys