Hi Everyone,

I have a 02 3.0L with 120K. I have owned the truck roughly 8 years and never noticed if this was abnormal from the coolant temp. On a cold start after driving a little bit I notice the temperature goes up a little above the half way marker for 2-5 sec then back down to where it normally sits a little below the halfway mark. Coolant is full and I have both cold and hot air.

My question does this seem normal? Maybe the 2-5 sec spike is the thermostat opening? Did I just never notice this before, or is it indicating a potential issue?

Thanks!

I think your thermostat is sticking closed and then opening late. I'd change it before it stays stuck closed and overheats your engine.

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1998 ranger extended cab, 2wd, 4.0 ohv, 5 speed, sony xploid 52 4 way watt radio, 2 pair of pioneer 240 watt speakers, Cobra 29 LX LCD CB radio pushing 100 watts, k&n air filter, 15 inch exploder wheels, dual exhaust with 4 inch stainless tips, 2 12 inch subs with a 1000 watt amp just for the hell of it!

new project: dirt track modified racing at the local saturday night track.

That is what I was thinking. For all I know it is the original on the truck, I bought it at 68K. I just thought it was odd behavior for the thermostat, in my past experience they just seemed to up and quit. Should I just assume that and replace the thermostat, or anything else I should look for ?

Thanks!

What you are describing is entirely normal,,, you just haven't noticed it before... the thermostat warms up the engine, pops open some ,, the engine takes a gulp of cold water and the thermostat closes off again until the temp comes up enough to make the thermostat open again....
there is a little mod that you can do that will change that behavior... drill a small hole in the flange of the thermostat that will bleed the warm water into the cold side... this eliminates the hot/cold shock that cracks the plastic end tanks... warm up will be a little slower but the benefits are worth it.... Doc,,,, " Widely unknown "

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2000 ford ranger with 3.0 Vulcan engine/auto trans/AC/PS/PB all bone stock...

Interesting. Yes by no means is it overheating, I just cannot believe in the 8 years of owning the truck I never noticed it move like that. It is definately a 2-5 second above normal temp before going right back to where it is supposed to be. All of my other vehicles never do this, they climb up to regular operating temp and stay there. hmmm