Over heating

07 Tacoma 4.0 crewcab 450,000 miles.
I’ve never really had a problem with anything under the hood of this truck until just recently. I started to overheat quite easily. Looking into things I discovered I needed a new radiator cap. That’s all it was. This lasted for about a month and then I started to overheat again. So I change the thermostat. Yes corrected thanks for yet another month. Then today I replaced my fan clutch. I took it for about a 45 minute drive. The needle stayed right in the middle just as it should be. However when I arrived at my destination I popped open the hood and noticed that there had been some leakage through the reservoir bottle. Then check the needle again as it was parked and idling. Then it started to climb again to the red barn at the top indicating it was overheating. I’m kind of at a loss because I could find no leaking around the water pump area whatsoever. It tends to only really overheat at slower speeds or tight traffic. Any suggues

 

Just starting with the obvious, does it have enough coolant? I mean, you're topping it off while the engine is running and the thermostat is open, right?

 

Is it blowing out any white smoke from the exhaust? How does the oil look? How does the coolant look?

 

What you describe is typical of a defective fan clutch. Did you replace it with an OEM Fan Clutch?

https://www.popularmechanics.com/cars/how-to/a302/1772922/

Did you get all of the air pockets out of the engine block when you replaced the thermostat?

What you describe are typical symptoms of air pockets in the block.

With the radiator cap off and parked with the radiator uphill allow the engine to heat up until the thermostat opens and you see circulation of the coolant in the radiator.

Then massage the hoses by squeezing them and topping off the coolant as it goes down. It may take some time to get all the air out.

 

4.0 block has 2 drain plugs down low so did you open them and flush the coolant and crud. After other ideas above look at the radiator core for flow - any clogging will cause over heating also. Most auto stores lend pressure testers so pump it up and look for leaks.

 

Hoverlover

No, I only have been topping it off when the truck is cool and off. I will try that today. When I do top it off it’s fine until I drive for a while and it loses more then starts heating up again. I will try that though this morning

 

JimmyH and Muddog321
The fan clutch came from O’Reilly auto parts as suggested by another forum here and they said it’s working fine. It was 78 dollars vs the 150 the dealer wanted. Maybe it was the wrong decision. I will try those things you suggested today and report back.

 

Thanks all!

 

if nothing irregular is noted in your oil or coolant, next on the list Id suspect a bad/clogged radiator.

 

Bad headgasket.

 

Is the fan running properly?

 

Is the belt sliping on the fan pulley at all perhaps?

 

So I parked the truck on an incline. Took the radiator cap off turned the truck on and let it run for about a half hour. Went back out and added about a half gallon of antifreeze to top it off. Then let it run another half hour. The whole time the temp needle was perfect. I massaged the hoses and tried To feel for firm spots. Changed the oil. No signs of water in the oil And no white smoke in the exhaust. Taking it down to have the pressure tested.

 

Kidsthatsirish

No appearance of belt slippage or squeeling at all. The belts also new.

Thanks

 

Tacoma sport

Fan and fan clutch are brand new. They appear to be working good

 

@b_r_o
@Jamesboy2233

 

Signs of a blown headgasket (just examples, not specifically your truck)...

- coolant level mysteriously goes down slowly over time and there are no external leaks

-fails a chemical block test

-shiny/clean pistons while looking with a boroscope

-excessive pressure in cooling system pushing coolant past radiator cap into the overflow reservior

-cold start misfires that go away after a minute

-erratic temp gauge readings while driving

-if you have access to a exhaust gas analyzer you can hold the probe tip near the rad cap while the engine is running and see if it detects HC

-yes you can look for white smoke out of the exhaust but dont be fooled by the normal moisture that comes out when the exhaust heats up

- cylinder pressure testing that produces bubbles out of the radiator

 

A half gallon low sounds like it may have been a contributor. Keep an eye on it now and let us know how it does. You may be fine after changing the cap, thermostat, etc., and just needed to properly top it off. If that doesn't fix it long term, you might try a good coolant system flush and see what crud comes out.
When you looked down into the radiator, how did it look? Any corrosion build up?

 

Sounds like maybe your radiator cap went bad and you lost coolant and perhaps when you subsequently replaced the cap and thermostat, the system wasn't burped of air correctly. Now that you have done the proper burp and added 1/2 gallon, you should be okay now.

 

get an oil analysis from Blackstone.they will tell you if you have a bad head gasket. Go someplace where they have a temp gun you can use, shoot the radiator all over when motor is good and warm, cool spots on a hot radiator indicate a plugged system