Overheating after buying 02 Tacoma

Hi everyone, I had finally scored a clean 02 Tacoma double cab 3.4 V6 4WD with 183k miles. All fluids are topped and looking fresh.

as I drove home from purchased noticed the engine coolant gauge went up to the high end and even to the red. I turned on the blower to get hot air out and noticed the gauge would come down when coasting like that. Would rise again in traffic until I got it home.

Checked the rad fluid at cold and it was topped with green. And the tank next to it was also filled.

Hooked up a OBD to read live data engine coolant temp while taking it for a drive and it read 230 Fahrenheit when the coolant gauge got up to the red mark.

Seems like gauge is working along side rising temp so I ruled that out.

What can I do next ?
Thanks!!!

 

take it back

 

Not helpful

 

If you're unsure what to look for (cold/hot hoses) to confirm that coolant is actually flowing where it needs to, it's safe to assume it can be something as simple as a thermostat. There are other things to check as well but let's start simple.

Fortunately it's very simple to replace, just make sure you get a nice 6 point socket so you don't strip the nuts that attach the housing.

 

While the OP didn't state this was a private party sale, at 183k miles and being an '02 it's safe to assume this is an as-is sale just like every other private party sale would be.

 

Yes as is sale. Are you speaking of a thermostat sensor that in the front under the timing belt cover or the sensor that is towards the back firewall? Thanks

 

Thermostat.

It's not a sensor - you're confusing it for the engine coolant temperature sensor and engine temperature sender which neither are the case.

Your thermostat, if it's stuck, wouldn't open up to allow coolant to flow through the radiator.

 

I had a similar situation, though the seller drastically discounted the price because he was tired of the intermittent over heating. The truck was a late 80s Toyota pickup that I was able to nurse it home without too much trouble. Upon investigation, I discovered that some of the radiator mounts were broken. This allowed the lower part of the radiator to move inward when driving, which in turn would crimp the lower hose. May not be your issue but simple to check.

 

Start with replacing the thermostat. Use only a Toyota thermostat, yes it is more money and there IS a difference.

 

Idle the truck and sniff the tailpipe. If it smell sweet, you might have a crack head (known for 5vz), bad head gasket, or cracked block.

check the coolant level and keep an eye on it to see if it’s dropping. Spin the fan clutch, honestly, I would replace it. Might be original.

 

After you get the coolant flow situation under control (maybe air in the system?)
You might oughta plan on going through all the regular maintenance systems. It’s better to drain good stuff out and know for sure what’s in your rig. It also helps with the bonding process.

 

How handy are you at working on your vehicle? You need to perform some simple diagnostics to determine if the cooling system is functioning properly. If you can do that, then you'll move on to a compression and leak down test. If these are new concepts to you, it's probably best that you take the vehicle to a mechanic who perform them for you. IF you're lucky and there is something simple like a bubble in the cooling system, it'll be an easy fix, but if there is a deeper issue, you'll need to start looking for a new motor and someone to do the swap for you.

 

Ok thanks gotchya. But if the thermostat was stuck would the coolant level gauge rise moderately and lower moderately like I mentioned on OP.

 

Damn! I did notice the sweet smell from exhaust..I think. But also smelt like an exhaust smell that was familiar from older cars. From what I read the 90’s years Tacoma had the head gasket issue not so much the year 2002z regardless I’m sure it can happen. I didn’t notice any milky oil or any white exhaust smoke which are usually signs on head gasket.

 

If it’s all not too deep down in the motor or needs a lift I can get my hands dirty. Have some experience with used cars.

 

A bad HG don’t always mean coolant will enter the engine. Depending on where the damage is located, it can enter the combustion chamber and burned off, exiting the tail pipe.

 

Dont over-think this. Put a thermostat in her and see if that fixes the issue. If not then the next step is a radiator. Thermostats can stick closed, open and part way.

I find it odd that it did not show during your test drive.

 

There are many reasons for this - whenever someone brings me along with them to buy a vehicle, I'll do things like let the vehicle sit and idle after a test drive

Listen for odds and ends after it's warmed up, confirm everything is working, letting the thermostat to open up and keep the vehicle cool as needed, test all gears, test all lights, inspect body panel bolts for signs of removal (hatch and hood included), decals on glass (to see if it's been replaced), and more

Not everyone knows these things unfortunately, as not many people are mechanically inclined

 

OP:

Congrats on your new truck. Looks super nice! I hope your problem is minor - but be prepared for anything. My gentle advice:

#1) Let this be a learning lesson for you. I would suggest an oversight you made was purchasing a 20+ year old very high mileage truck without test-driving it long enough to discover this condition. Or taking it to a shop for a pre-purchase inspection. Ooops. Learn from this for the next time.

#2) If you do not know a whole lot about these trucks, that is 100% A-OK. But just please be correspondingly self-aware. That is not a criticism. It is just a sharing moment to use your time, energy and $$$ wisely.

#3) It drives me absolutely crazy when owners just start randomly changing parts trying to solve a problem without logically correct reasoning to do so. (And when others in this forum also suggest the same.) Please do not take this approach. It is terrible approach. Proven time and time again to be wasteful in terms of time and money. Think about this. --> There is not a dealership or independent shop anywhere that would say to you "Oh, your Taco is over-heating? Well, let's just install a new thermostat and *hope* that resolves your issue. If it doesn't, we'll take another guess at a different part and replace that and hope that resolves your problem. And we'll keep doing that over and over again. NFW.

Figure out why you are over-heating first. And then resolve that condition.
--------------------
#4) It is somewhat possible you have an air-bubble (air-pocket) in your cooling system. Especially if the coolant was just changed. Mild overheating like you are describing is a typical result of an air pocket still trapped in your cooling system after a fluid exchange. One simple way to resolve this condition is to remove the radiator cap and let your truck idle in your driveway for 5-10 minutes. Just keep an eye on the temp gauge on the dash and the actual ECT (engine coolant temp) sensor reading on your handheld scanner. Often times, the air bubble will find the path of least resistance and eventually "burp" itself out your radiator cap opening. It costs nothing and hurts nothing. If your radiator cap at any times starts frothing over, shut down, cool off and start over. Do this 3 or 4 times.

Meanwhile, as you are doing this with your hood up, check your serpentine belt. Is it spinning at the same revolutionary frequency as your water pump pulley? Make sure you don't have any pinhole leaks spritzing or dribbling coolant anywhere. Let it idle. Let it idle all the way up to 200F or so. Shouldn't get higher than that. You should see fluid moving across the top of your radiator cap opening.

Note: I am not super familiar with 1st gen engine cooling fan operation. IIRC, your cooling fan is a viscous, belt driven fan. Meaning it always spins (slowly) when the engine is running. And it spins faster when the engine heats up. IIRC, your cooling fan should spin by hand relatively easily when cold and the engine off. But when the engine is shut down under a warm condition, it should spin less easily ---> meaning it is viscously coupled as it should be. Simple hand and visual check.

#5) Your next diagnostic troubleshoot techniques are as follows:
a) Conduct a cooling system "block test". You can DIY with a $25 test kit from any auto parts store. This test is intended to determine if you have combustion gasses in your coolant. Which is indicative of a head gasket leak or engine block crack.
b) Pressure test your cooling system to 20-25 psi. Get a kit from Harbor Freight and you can use your bike tire pump. Seriously.


HTH and good luck

 

If you have a clutch fan in might be no good.