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

Hello all, It’s been getting pretty cold up here in the north and I rarely pay much attention to my temp gauge. But today after a good half hour drive in 25 degree weather I realized that my temp gauge still hadn’t broke the 1/4 mark. I remember having issues with the engine temp dropping at idle as many others have stated on here, but it always climbed back up to the 1/2 mark while driving.

I broke my oem hood scoop awhile back (trd sport) and just ordered a new one tonight so blocking that hole on the hood should help hold some more heat. But I can’t imagine that small hole in the hood would affect engine temp to the degree I’m experiencing.

But anyways I busted out the cardboard earlier and slid a large peice up in between the rad support and radiator. It effectively blocks off about 90 percent of the rad. It is the full height of the rad and leaves about 2 1/2 inches or so open on the sides. But I’ve gotten nowhere my temp gauge still will not even get up to the 1/4 mark. I have verified that it’s truly not getting up to temp and not a faulty sensor by the heat output, on the high setting it’s only putting out “warm” air through the vents.

Anyone else had any issues? I’m guessing my t stat is stuck open or something because I recall temps being -20 or so in previous winters and it never stayed this cold while driving before.

Oh I also just threw on a new cai yesterday so maybe that thing is just the best cai I’ve ever seen

 

Sounds like a stuck possible thermostat but would be a bit premature for a 5 year old vehicle, how many miles do you have on the truck?

 

I thought the "scoop" wasn't actually a scoop?!

 

I just broke the 40k mark a week or so ago. But 20k of those miles are pretty much ruthless beating. The poor ol girl just takes em and laughs at everything I throw at it haha

I’m not even sure where they stuffed the t stat on the 2grfks, I guess I’ll have to do some digging. Not looking forward to wrenching in this weather but it is what it is I guess.

Also the engine probably isn’t even actually as warm as I thought when feeling the heat coming out of the vents. I completely forgot that our 3rd gen v6’s have an auxiliary electric heating element that runs while engine temps are low, and the heater is on the high setting. That poor little guy got its fair share of use today.

 

The t-stat is monitored by the ecu, there will be a code if its not behaving correctly. Plus there is a serious shortage of t-stats for 2grs right now, you couldn't replace it if you wanted to.

It's cold, time for cardboard.

 

So, common problem area, or just one of the supply issues that are all too common these days?

 

Well it is now funny story actually, I had modded the scoop awhile ago to make it a functional scoop. I wanted to help the ol girl breathe a little more while out wheeling in the hot summer temps.

Well that proved to bite me in the ass because I was racing a buddy of mine down a 3 mile straight stretch and right around the 105mph mark the scoop caught wind and blew off quite spectacularly i might add. It hit the windshield and I seen it about 30ft in the air in my rear view. So that was a 130 dollar lesson learned, the scoops are not open for a reason

 

Ive got just about the entire rad blocked off atm and no dice. And the cardboard is directly on the rad. Stuffed it up between the rad itself and the support and it’s nice and snug. There are about 2 1/2 inches open on each side but other than that it’s completely blocked.

I wasn’t aware that the ecu had a part in the cooling system though. Luckily I have vf tuner and techstream. So I guess I’ll go log a drive tomorrow and see what’s actually going on.

 

Just over a year ago my 2018 with 31k had a stuck open thermostat. It never triggered the check engine light or any codes at all. It took much convincing of the dealer that there was an issue until I took the tech on a ride along.

They might be modern vehicles, but the cooling system is still controlled by a $50 thermostat, no matter what data logging goes on.

 

The thermostat is right here at the front on the engine. It's an entire plastic assembly.

 

OP, my truck is throwing a P0128 code for a stuck thermostat. I just ordered the part here in Germany yesterday and the dealership won’t receive the new thermostat until late April. Unfortunately I’m paying out of pocket since my warranty only covers repairs made in North America.

My 2020 has about 12,000 miles and this shouldn’t be an issue but I guess Toyota reliability has dropped in recent years.

 

Have you pointed an IR temp gun at the various cooling bits to see where things are hot and where they might be blocked?

If everything shows about the same cool temps all around, I would certainly suspect a stuck open thermostat.

 

Imo, at least with the sr5 grille, these trucks might warmup better with a grill cover when its that cold. Wonder if anyone has try adding one.

 

A stuck open thermostat in cold weather is not fun at all. I must say that most post generally are looking for ways to cool the engine and transmission.

 

check coolant level if you haven't

 

I still have not figured out the multi quote on here so forgive me guys.

First off I just want to add the the temp gauge does fluctuate. If I keep the rpms up while driving at low speeds through town it will come up a bit but still never makes it to the 1/4 mark. It’s also kind of erratic, the needle bounces back and forth about 1/16 of an inch while driving.

@PlymouthJLA and @Patriotgrunt I have not thrown any codes as far as the cooling system either. Also Plymouth is right about data logging, it won’t solve anything but it will at least let me see what the ecu is doing (or not doing) to try and get engine temps up. I have noticed that the truck does idle up with the clutch in and brake on, and heater running. So I beleive the ecu is aware that the truck isn’t warm. The idle up is more than likely due to the electric heating element putting load on the system. And the heating element will only switch on when engine temps are below 65 degrees if I’m correct.

I beleive it’s safe to assume that if the thermostat is stuck open the ecu may not always recognize that there’s an issue, and that it would just think that the engine is still (warming up) the only way it would be able to tell if there was an issue is if it compared run time to engine temp. And with these trucks getting cold at idle I’m guessing Toyota wouldn’t have it set up that way. They would have tons of complaints about cel’s in the winter if so. That is just my theory and I very well could be dead wrong though. I’m still trying to figure out how the ecu can tell if the tstat is faulty. Maybe it only throws a code if the electrical portion fails, that would explain it not throwing a code if the tstat is stuck open mechanically.

@INSAYN As for getting temp readings I’ve been staying at my girlfriends house about a half hr from home so I’m stuck with basic tools out here. I will get out the temp gun tonight when we go to my place though and start getting temps.

@desmodue I took a peak at the coolant level yesterday and it looks good. Although I have never checked it with a coolant tester to see if the mix ratio is higher on the coolant side. The truck is actually from Canada so I would assume that it’s seen harsh winters in the beginning of its life. It was also immaculate when I bought it, and had only 10k miles. The original owner in Canada owned a car rental buisness from what I gathered, and he had put a lot of time and money into the truck so I think it’s safe to say he probably was meticulous about coolant/oil. But I still am going to grab a tester on the way home and give it a check. I’m 26 and have always been on the neglectful side, but that’s starting to change so I’m going to give the ol girl a good once over.

And @Greg-tacoma your absolutely right, I’ve never really had issues with keeping it cool in the summer as it rarely gets over 100f up here. And I couldn’t beleive it when I realized it wouldn’t hold temp when driving in 20 degree weather yesterday. I’ve never had issues in the winter in any of my Tacoma’s and I’ve owned various trucks with both engines in the 1st and 2nd gens. The cooling systems have always been great no matter how hot/cold it got up here in pa. But the 2gr is a whole different animal. I do like it but I find myself wishing it was a 4.0 quite often. My 06 4.0 took the most abuse I’ve ever thrown at a Tacoma and is still running like a champ. I went around 70k between oil changes on that truck, and in that time it probably spent quite a few hours at rev limiter. When I finally changed the oil it looked great! There was hardly even any brass in it and it had a good color for that amount of miles/abuse. IMO that 4.0 is as bulletproof as a 22re.

 

Your symptoms are the same as mine. My engine first threw a code in December and I cleared it while I was doing some research. I’ve been watching it for two months. I can usually throw the check engine light when I get on the autobahn and open it up.

Try getting it on the interstate after it’s warmed up and run the truck a 80 mph for a while. The truck should throw a code if the thermostat is bad. Driving around town and local roads won’t trip the computer from my experience.

 

All i can say is my truck seems to take forever to get up to normal operating temp. Been pretty cold today, i went into town and back to pick up a prescription of mine. Truck never fully warmed up....and that was a good 10 minutes, or more each way. My tundra would been throwing heat long before.

 

It’s been between 5F and -15F here all month here and I never bothered to check my engine temp gauge. Is my truck ok?

 

Find a new thermostat and Just change it. Heat will return