Cooling System Issue

[Peccarelli]

Hello, this is my first post in The T4R Forums. Great website always come here for the little knick knack problems and questions I have(Usually already solved for me). I've searched quite a bit on this forum for the problem I'm having. I've found a few related posts in the forum; but no direct answer. So I apologize if this is a repeat post.

Just bought my first 4Runner a few months ago. It's a 2001 SR5 in which it only had 96k original miles, very clean truck. It's been my daily driver since. Soon after purchasing the check engine light came on and TRAC control turned off. The code was ran and relayed the message "thermostat temp too low".

Once I decided to replace the thermostat, I find out that there wasn't one inside the housing. This through me off right away because all my gauges were reading normal. After putting the new thermostat in and getting everything back together, it decides it wanted to overheat. It won't overheat just sitting there idling but once you cruise a mile down the road the tempature slowly begins to redpeak. So I took the thermostat back out and it runs fine again.

Did some research and gathered some opinions from a few people and decided maybe the radiator is clogged. After replacing the radiator and doing the whole thermostat process it still wants to overheat. It now remains without a thermostat in it and continues to be used as a daily driver. I do not want to bring it into a Toyota Specialist yet as I don't want to see the cost of labor; and it runs fine. I'm stumped.

So what's your opinion T4R community?

 

[BrianSD_42]

OK quick advice here. If you recently changed the tstat there is a chance you have air in the cooling system. Air can be difficult to diagnos and it may need to be properly bumped.

Also get a scanguage or $30 OBDT-2 Blutooth device (Amazon) and use the Torque App on Android.

If it is hitting red then there is an issue. I wouldn't run it red at all.

 

[TheDurk]

Did you install the stat with the jiggle valve down, as the FSM instructs?

Once that is verified, put the front wheels up on a curb, pull the rad cap and run the engine until you can see the flow in the top of the rad. Let it go for a few minutes, then cool it off and fill to proper level. I bet that does it.

 

[Peccarelli]

It will only run hot when there is a thermostat installed. Im currently running it without one without any overheating. And I'm pretty positive there's no air in the cooling system. I've tried a few different tstats; including the jiggle valve one.. I can open my radiator cap and watch the water flow quite nicely, no hiccups. Thank you for your replies, but more input please? What's this bluetooth thing your talking about?

 

[the great him]

what if you run the truck with the heat on does it still over heat? what tells you its overheating?

have you tried doing a coolant flush with a cooling system cleaner or flush kit?

 

[nissanh]

You might want to check the coolant flow in the radiator. Open the radiator cap and since you don't have a thermostat, you should be able to see the coolant flow in the top tank when the engine is running.
The reason why I say this is because I vaguely remember we had a member who said the blades in the water pump has come off from the water pump shaft hence no water flow. Yes, he had a non-TOYOTA water pump.

 

[BrianSD_42]

It will only run hot when there is a thermostat installed. Im currently running it without one without any overheating. And I'm pretty positive there's no air in the cooling system

How do you know there is no air in the system?

 

[awpsome]

seems like from your posts you are taking the tstat in and out multiple times.
Meaning you are going through having to fill new coolant everytime..

most likely air in the system..
or bad radiator. or fan is going out,.

 

[scrap metal]

Does it only overheat on the street or on the freeway? If it does not overheat on the freeway its not the fan.

Flush the cooling system. Confirm the radiator and water pump is good.

Stick to the toyota t-stat... the other ones suck.

If you are overheating on the freeway after all the above is checked then I would lean toward head gasket leak.

I had a 93 toyota pick up with the 3vz that would overheat with a tstat installed... without the tstat it did not overheat on idle or on the street.. only overheated on the freeway. It was a headgasket issue.