3rd gen 3.5 won’t get up to operating temp

FWIW my gfs honda fit was taking too long too warm up and i swore it was thermostat stuck open....it ended up being one of the 2 coolant temperature sensors were bad (it actually was warmed up just getting a bad reading to the computer,thus throwing a "taking too long to warmup code"

 

I realized that once I went to start tearing into the truck. I’ve always had this kind of luck though. All well I’ve managed to fix my oem one until I get the right replacement in.

 

Alright so I had some time this afternoon to tear the assembly off and see what was going on with it. I was sent the wrong assembly as @zacci

I had verified it wasn’t the sensor by taking temp readings all around. Gauge read 1/4 and all temp readings were around 118f and the normal operating temp is around 240 I can’t remember the exact number atm. So the gauge was spot on. That’s when ordered a new one.

 

[update]

I found the time to tear the assembly off tonight, parts geek had sent me the wrong part for a 3rd gen “without towing package” which it is what it is. I inherited the family’s bad luck so I’m used to it.

Anyways I managed to tear into the factory assembly and found the issue. It was in fact stuck open. And the culprit was a plastic bushing. It was sitting sideways and preventing the thermostat from seating fully as you’ll see in the picture below.

I corrected it by filing it down flat so that the thermostat would seat completely again and it works, I cannot blow through the housing whatsoever and before filing it flush It was free flowing when blown through.

I would say that this is a design flaw on Toyota’s part. That plastic bushing kind of floats around in there, enough that it managed to work its way out and get wedged at an angle. My truck has a little over 40k on the clock.

I decided to tear into the beck/arnley and see if it was the same design with a plastic bushing but it was not. It was solid brass and appeared to be very well designed compared to the oem stamped metal and plastic bushing one. I didn’t get any pictures because my phone died but I will post some of the internals when I get the right part in. I’ll do a comparison of the guts of both assemblies when I have them both off.

I just want to mention in the picture you will see a small slit in each side of that plastic bushing, they let coolant contact the temp probe when fully closed. I did not replicate them when I filed it flush and it seems my temp gauge is reading lower than actual engine temp now. But I did fix the overall issue until I can get in my new assembly. I have heat, and my truck is much happier and running at normal operating temp.

 

That's not a sensor in the t-stat, but rather a preheat device which helps the thermostat open very quickly. Toyota runs the coolant temps in the Taco a little hotter than normal, which in my best assumption, places the cooling system a bit closer to the edge. There's no time to waste with a regular old lazy t-stat.

 

Hmm really? That’s odd, if that’s the case the bushing that rides on the heat probe is just made of plastic and plastic doesn’t transfer much heat. That thing would need to be extremely hot to heat up the assembly enough to open. You have to figure that the spring needs to heat up to open the tstat. So that probe would have to transfer heat through the coolant between it and the metal tube that encases it. Then the heat would have to transfer through the coolant in the tstat housing to begin opening the thermostat. And those puny wires leading to it can’t pass much current so I would say that it probably doesn’t work all that well. But I guess we will find out. It’s getting unplugged next time I let out the pooch and I’m going to see if It heats up any quicker just out of curiosity.

 

Here's a handy dandy diagram right from Toyota. Not sure if it is helpful.

 

Hey man any information is helpful in my eyes, I like to learn. There’s not much easily accessible info on the 2grfks so yes that is helpful lol it’s just crazy to me that that is supposed to get the surrounding area hot enough to let the spring open. But I suppose if their goal is to help the tstat open “faster” then that heater probe probably only comes on when the coolant is just about hot enough to open the tstat on its own. So I suppose it could be effective in bumping the temp up just enough to open it quicker.

Are you able to throw the link up to that information for me, and any other curious people that stumble upon this thread?

 

[Update]

New (correct) tstat arrived today at my parents house. Which is absolutely mind blowing considering I had just ordered it just a day and a half ago with standard shipping through fed ex. It was shipped from Hempstead NY which is 400 miles away.

But anyways I’ll get it swapped in tomorrow while I’m at there place doing my left side upper ball joint, diff fluid, and rotating my tires. (Man I wish I had a garage) I will report back with pictures of the new assembly and quality/functionality once I get it swapped and go for a drive.

I know the beck arnley assembly I received was much higher quality than the oem (the entire inner section was solid machined brass rather than the oem stamped metal with a plastic bushing) so hopefully this one is is as well.

Oh and I almost forgot, new hood scoop arrived Monday and I wasted no time throwing it on. It definitely helped some. Warms up a little faster and temp takes a bit longer to drop. This info is purely for any young dumb guys like me that want to make your scoop functional. Just don’t. It may keep ambient temps under the hood down, which is nice in some situations but it’s not worth it.

 

Hey OP. I came across this thread.

I think i had a reverse issue where my thermostat was more closed than not. I boiled it and it moved but i'm not convinced it was enough. How did you ge tthe thermostat out of the housing? brute force? that spring in there scares the living daylights out of me to just push down with my hands and twist...

 

Any tips on replacing the thermostat? Can’t find enough info about it.
Do i have to do some kind of bleeding afterwards?

 

commenting on the same issue - running cold and replaced with the beck & arnley through rockauto, issue resolved. under $100 part and $50 worth of coolant will save you tons of $$ at a shop. bolts on the thermostat are a pain but doable with average tools. '17 taco @40k miles, I'd blame toyota but I do bounce around the mountains of Colorado ALOT

 

When I did mine I used hose clamps to pinch off all the coolant lines, swapped out the thermostat. Lost some coolant but not much.