False temp/Fuel gauge readings?

[wrkngmanByTor]

Ok, so recently I did tstat&coolant flush to correct an overheating issue. Other than having to swap out the cheapo napa replacement tstat with the Mazda one, it all worked out. Until now. Random times the temp needle buries itself at the top end. I tried cranking the heat/fan, sometimes brings it down, sometimes not. Then crank it back and when the temp had lowered, it did not return to high. This happened during an easy 20 minute drive to work in cool weather, then after work I took a 45 minute drive through stop and go traffic with no overheating indications. I am getting no cel/mil's, no squealing or noise from water pump/belts, overflow tank level is stable. Coolant temp shows(when I assume the sensor is functioning) to rise normally at warm-up, unlike sluggish warm-up time with old stuck-open tstat. Oh, one other thing that makes me thing maybe something in the instrument cluater---my fuel gauge went UP from the "E" line to nearly the 1/4 line at one point, then after putting ten bucks worth in the tank, dropped to near E again. Please, does anyone have any idea whats going on????

 

[tweety2300]

First you need to find out if it's really over heating or not. If you drive it while it's that hot you'll end up warping the head. My gauge has done the same thing it acts like it has a reserve or something. If its that empty why only put $10 in it? Fill it up and see what happens

 

[wrkngmanByTor]

First you need to find out if it's really over heating or not. If you drive it while it's that hot you'll end up warping the head.

I'm 99.9% sure it's not actually overheating because I could hold my hand on the rad cap after the first occurence. And no expansion-contraction engine block ticking noises after shutting down.

 

[tweety2300]

You realize it normally runs ~190 degrees right? 230 and higher can warp an aluminum head

You may just have a bad temp sending unit

 

[wrkngmanByTor]

yup. I've got a multimeter - is there anyway I can test the sensor with it?

 

[wrkngmanByTor]

I guess maybe I could go to my local shop and get a reading with an ir temp gauge the see if its within normal specs?

 

[tweety2300]

You can get a temp gauge at autozone for 20 bucks. If it doesn't happen a lot taking it to a shop will do you no good

 

[wrkngmanByTor]

$20? for an infrared? Wow, didn't know they were that cheap. No advice on diagnosing with the meter?

 

[tweety2300]

Getting to it with a multimeter won't do you any good unless it messes up while you are reading it.

I'm talking about an actual aftermarket water temp gauge

 

[wrkngmanByTor]

True enough. well, maybe I'll install the gauge if its not too difficult, then check it when the engine"overheats".

 

[tweety2300]

You don't have to leave it hooked up forever just splice it in with the oem one and set the gauge in the cup holder