Is my mazda truck overheating???

[Mazda Truckin]

I just bought a used 2003 Mazda B2300 40k miles and I noticed that the coolant temp gauge measures past the middle to about 3/4 to the red hot region, but never reaching the red zone. It happens after 30 mins of driving even at a cold night w/o AC and with an empty bed. It seems like it rises when its idling and it goes back to the middle when I start moving again. I dont know if this normal because this is my first mazda vehicle. The truck is still under warranty, but I'd like to hear your opinions before I go to Mazda service. But I wonder what will happen if I haul cargo up a hill with the AC on a hot day.

My Honda's dont have this problem and it always reads below the middle even on hot days with AC on. But other than that, the Mazda seems to be okay.

Thanks for your input.

[mudseeker]

the engine is cooled by air forced over the radiator, when the truck sits the temp may rise if it sits for a long period of time. depending on where you live you may need a thermostat in a lower heat range.

[72'CaminoKid]

i concur with mudseeker

[Mazda Truckin]

Yeah I'd like to try switching to a new thermostat and do a coolant flush to the radiator and engine block. Do you know if that work will be considered to be warranty? The owners manual says to do a coolant flush at 45k miles and I still have 40k. I'm not trying to be cheap or anything, but just wondering.

[mudseeker]

i think that would be considered regular maint. and thats not covered under warranties. before you do a flush check the condition of the fluid. if it still has good color and no corrosion is visible just replace the thermostat.

[Mazda Truckin]

I see. Looking at the coolant reservoir the coolant fluid is yellow in color and it appears to be clean.

The weird thing is that I was driving on the freeway yesterday with the engine warmed up and the temp gauge dropped to cold (about 1/4 from cold to hot) all of the sudden. Then the temp rose slowly back to the middle. So I have a feeling that the thermostat is stuck. And it must have opened somehow and the coolant must have really cooled the engine. Since the vehicle was sitting at the dealer lot for a couple of months, maybe it got stuck temporarily. lol. Ill keep my eye on the coolant temp for these couple of days.

If it overheats again, I think i'l just take it to the dealer and have him replace the thermostat, hopefully they will do it under warranty.

Thanks.

[lithopro]

You could also have a faulty temp. sending unit or temp gauge. Maybe just a loose connection between the 2. But I would suspect the thermostat. When you take it to the dealer, don't let them tell you "there seems to be nothing wrong here, it's working fine".

[72'CaminoKid]

to check your thermostat, just drop it ina pot of water that you know the temp, and see if it opens and closes when it should

[gmctrucks]

I bet the water level is low the gauge will read real weird when it's low remember don't take it in till you check the water level. Just to be safe I would take it in for peace of mind not unless you have to pay something and alway's ask on seeing the part that was replaced even if they have to send it in for warrenty. But again im thinking it's the waster leval in radiator and reservor. MUDSEEKER has a good point.

[scottie]

sound definitly like a thermostat. theyre only like 3 bucks, so it would be worth just replacing to see if it makes a difference.