Question: Tacoma normal water temp?

[01tundra]

A little update. I decided to change the timing belt and water pump on my '03 Tacoma 3.4L over the weekend. I went back with all Toyota parts, including a new thermostat (just like I did on the Tundra). Before the timing belt change my scan gauge would read a consistant water temperature of 186-190F, after I got it back together with the new 84C thermostat it was running 204-206F. Went directly home after test driving it, pulled the new t-stat, threw it in the trash can where it belongs, and reinstalled the original t-stat. Took it back out for a drive and it ran 186-190F again.

Two different engines, two different time, both factory new t-stats, both trucks ran 10-20F hotter after the change. Toyota has changed something on their thermostat construction and it sucks IMO. That will be the last t-stat I purchase from Toyota. I tried three different new Toyota t-stats in the Tundra with the same results, put a Stant in it and it ran the correct temperature.

I'm sure the warmer running temperature won't hurt most people, but while in the woods during the summer I was seeing the Tundra temperature approaching 220F, where prior to the t-stat change it would rarely get to 200F.

If Toyota is going to change the operating temperature of their t-stats, then the lazy a$$es need to change the 84C stamp on it as well so people know.

 

[downhill]

Very interesting thread, and thankyou for the update! I haven't been into my truck so no issues, but good to know. In the past though with other trucks I have found significant differences between the rated temp and the actual temp on thermostats. I never install a new one without testing it in water with a laboratory grade thermometer. One thing that wasn't mentioned is that the thermostat rating will effect heater output. Toyota's re-specing of the thermostat may have been to improve heater efficiency.

 

[austintaco]

update to the jiggle valve dilemna

I planned to do this when I changed out the water pump and timing belt, but I ran out of time for the big job. However, I purchased a new thermostat and gasket and planned to do a complete flush and fill and reinstall the thermostat with the jiggler in the down position.

Everything went well, except that the jiggle valve got caught between the lip of the thermostat and the casing and I couldn't see it. After the coolant rushed out, I tried to tighten the assembly until I heard a snap. That was one of the bolts, and then when I removed the thermostat, I realized what had happened.
The thermostat was destroyed since the jiggle part of the jiggler was snapped too.

However, with the old thermostat in with the jiggle valve at about the 4 o' clock position, and brand new coolant, the truck ran about 15 degrees cooler up and back to Colorado. I don't think my truck ever ran over 200 and that was with the additional weight of the flippac, more gear and armor(bumper, sliders, bikes), and I had the truck regeared so the rpm's were higher.

My thoughts are that some of this improvement can be attributed to the thermostat, but also to the new coolant. Somewhere along the way, Firestone ( I used to get alignments done there) added green coolant to my system, so I had a mix going on, and it was long overdue for a change.

Anyway, don't make the same mistake I made. Toyota parts are expensive and that red coolant was like gold running down my driveway! ( I had a brand new drain pan that I managed to put under there and salvage most of the coolant)