Temp gauge needle goes to Hot after warm up…

Recently my truck has had a subtle burning smell after a drive. Yesterday I took it in to Toyota for an oil change, and on the way the temp gauge needle went to max hot. I had the last appointment for an express oil/lube so they couldn’t look into the issue. I started it today and it did the same after warm-up. In the last few months the truck got a new front bumper, skid, winch, and cb. I will take it back in to get this repaired but im afraid to drive it… Any advice on what to check/do is appreciated.

 

Diagnose.

What did the burning smell like exactly; was it sweet smelling?

Any engine codes?

Is your coolant level low?

Any excessive white smoke from exhaust?

Pulling the oil cap, is your oil milky or still looking like regular oil?

Fan spinning as normal with engine running? Fan speeds up with faster motor speeds?

If all things look good and nothing I mentioned stands out, it could be something as simple as trapped air or a stuck thermostat.

 

Is the radiator full?

Thermostat stuck closed?

Cap not holding pressure?

Always start simple.

 

Dont drive it. Overheating the engine is bad. Get an obd reader with live date, no more than 50$ bucks at a walmart and autozone, check the temp, if its normal operating temp and the needle is up,could be something else. When was the last time you did the coolant? If it did overheat, could be the gasket, gonna have to take off the top, check compression.

 

Might have some air in coolant? why i ask

 

Okay, thanks all. I will have a look into this tomorrow. Love my truck but this kind of stuff is way outside my comfort zone.

 

Possible stuck thermostat.

 

I would highly recommend you buy oem parts only and get the job done at a mechanics shop, the stealership is just gonna bend you over. Shop around for 3 shops, gl and if you have any wuestions thats y were all here

 

Stuck thermostat blew up the truck in my avatar. Stuck at 70mph on highway, before I had a clue... it was done.

 

Could also be electrical too. If you've got a bad sensor, that could make the gauge max out without actually heating up the engine. Would be good to check that sensor with a multimeter.

EDIT: I take that back. After warm up says it all - definitely something mechanical.

 

If you have a smart phone I highly suggest getting a BlueDriver. It will help get a accurate read on the temperature.

 

Upper rad hose should be hot after warmup unless t stat is stuck closed. Could also be water pump, especially if burning smell is burning rubber (slipping belt). Check belt condition and tension. Let’s not throw the baby out with the bath water and condemn the head gasket until easy/cheap stuff is ruled out first.

 

I thought I would start with the OBD reader... arrived tonight. I connected it and... no codes found after the scan. Also, now when I start it, the needle goes to max immediately. So does this indicate a sensor or should the scanner find that?

 

What was the temperature on the reader? Probably a bad gauge.

 

There are 2 monitoring tools in your engine bay that read your coolant temps.

On a 3.4, a sensor is in the front (2 or 3 wire plug) that's found forward and below the throttle body, and the sender (1 wire plug) is to the rear by where the intake manifold ends.

The sender is the one to look at here as it sends 'information' to the gauge to tell the needle to move up or down. Not really accurate at all, and the main reason why others have told you to use your OBD2 reader to monitor temps.

 

I took a short drive, max speed ~40mph. According to the scanner, the coolant rose to 190.4F at the end of this drive. I watched the needle closely on start up; it maxed out a few minutes after starting; not immediately. I didn't watch it as closely last night because I was looking at the scanner app, so I probably missed it.

Which, if any, of the following should I scan?

 

180° to 200° is normal range for operating temps. Sounds like your truck is not overheating afterall.

I like to monitor battery voltage, coolant temps and trans fluid temps (auto only).