Overheating problem HELP!!

Ok my dad bought me a 2002 tacoma x-tra cab in july. It has 195,000 miles on it with a replaced engine. The first week I used it the check engine came on. We found out that there was no thermostat which made the check engine go on. I bought a thermostat from advanced auto parts. I installed it and spent a hour or two trying to bleed the system with the engine on(it doesnt help that the thermostat is on the bottom of the engine. It should be on the top of the engine). As the coolant level went down i just kept filling it up. After the system was full I drove it up and down the road and it began to overheat. I found out the thermostat wouldnt open and I took it out and went back to advanced auto parts and exchanged it for a new thermostat. I went home and boiled water and put the thermostat in the boiling water to make sure it opens up. It opened up! I put the new thermostat in and did the same thing to bleed it. I drove it up and down the road and the truck began to overheat again. I pulled into my drive way and let the truck idle and all of the sudden the temp. gauge went down to alittle above the 3/4 mark. I kept revving the engine and the temp went back up to the red line on the temp gauge. I kept revving the engine and the temp went back down around the 3/4 mark again. It kept doing this but it wouldnt stay around a constant temp on the gauge. I even drove it for a couple miles. I took it to my friends repair shop and he checked the thermostat and it was fine he put the thermostat back in and bleed the system. It still did the same thing but my friend mentioned to change the clutch fan because it doesnt engage at higher RPM's. So i changed the clutch fan and I could hear difference as the fan move more air. But that still did not help that much. The engine still over heated. I would always have to drive with the heat blasting and the temp guage would go up and down between 3/4 and the red line. My dad thought there might be a blockage in the radiator. So I bought a new radiator and installed it with a new thermostat from Toyota(the thermostat from toyota has a bleeding valve). That didnt make a difference it still overheats but when I blast the heat it doesnt bring the temperature down. because the toyota thermostat has a higher opening temperature. The thermostat I got form advanced auto parts has a opening temp of 180F.

Now I dont know what else that would cause it to overheat. Any ideas?

 

Now I am not sure what the waterpump does? Does it pump the coolant thriugh the engine? and the cooling fan is fine. It pulls alot of air through the radiator.

 

The waterpump is fine because when I turn the engine on and open the radiator cap I see the coolant flowing.

 

have you thought about maybe your temp gauge is having issues instead of the cooling system having issues. and also if you over heated the engine that is not good.

 

I dont think the temp gauge is having issues. The coolant system boils when it overheated a few times. There hasnt been any smoke coming from my engine from overheating. I know its not good. It would cost to much to get it fixed by toyota. I think its better to fix it myself if I can to learn more about it.

 

theres only so much that can keep it from overheating. either you have an air pocket in the system a bad pump or radiator or a blockage somewhere in the system

 

Do u lose coolant when u run it?? Try Washing out the radiator with a water hose (the outside) then the inside with prestone rad flush even if thats not the problem it will help! Is that the right fan clutch there will be different ones for different rear ends! Take the thermostat out and check this stuff no need for it to be in there now until its cold!

 

When they replaced motor was it the heads too? Could have a cracked head or head gasket! Jus bc there is water moving doesnt mean there is enough water moving!

 

I dont lose coolant when i run it. I just installed a new radiator. It does have the right clutch fan.

 

then ur only option is the water pump if ur not losing coolant it would be the only thing that would make it run hot!

 

That and a leaking head gasket that is letting hot combustion gasses into the coolant, heating it up. I would have the system checked for combustion gasses if you are 100% sure the water pump is fine.

 

Yeah rent a pressure tester and hook it up! If u see the pressure rise above the rated psi then your head or head gasket is cracked! Right bill? cause u wouldnt necessary lose coolant either!

 

Yep, pressure test the cooling system. So before when there was no thermostat it would not overheat but just a check engine light?

 

Well a pressure tester can check that, but I use a combustion gas tester that some places rent that will actually measure for combustion gasses in the cooling system. Yes, you can have a leaking head gasket without having a coolant loss.

 

^ this.

Only other random thoughts:

Don't remember, is it possible to get the thermostat in backwards on these? Just so automatic that I don't even pay attention anymore.

When you installed the thermostat you made sure the jiggle valve bleeder was at the top correct? Think 15 degrees either side is okay, but may as well put it straight up.

Also, is it a new radiator cap of the correct pound rating? Been years, but seem to remember every lb of pressure is something like 3 degrees cooler in the system.

Also, always run with a thermostat.

When you refill the system how are you doing it. I keep the top hose off and slowly poor the coolant mix in the engine through the top hose and then when full I connect the hose to the radiator.

Might have missed it, did you put new hoses on? Got to thinking of a hose sucking flat and causing an issue as you mention driving it and it overheating, but the temp went down when you got it back and just sat in the drive idling.

I'll go back to sleep now.

 

I dont think your head gaskets are bad. I would start with the waterpump. I have seen on higher mileage vehicles, the coolant fins rotted right off the water pump. It is from no maintanence of the cooling system from previous owner and using undistilled water for a long period of time. Also make sure the coolant lines from your heater core and the heater core itself are also flushed out. Is it a 4 banger or 6. I personally had a 97 tacoma with a 3.4 that got so hot it rolled to a stop. Head gaskets were fine. A freeze plug rusted through. The definition of a blown head gasket is when coolant enters the combustion chamber. You WILL have coolant loss with a bad head gasket. On most really small leaks the converter eats it up so you dont see any evidence of loss from the tailpipe. Just like Hillingdoner says, Fill and bleed the system from the highest point. Make sure its full and no air pockets. What also helps is to leave the cap off the rad untill the thermostat cycles once. You can get rid of extra air that way also. My guess would still be the waterpump since you said the temp comes down when idling. Hence not enough circulation at higher rpm's. And dont buy a waterpump from Advance. Get an ac delco or toyota pump.

 

I put the thermostat in the right way. it wouldn't fit the other way anyway. The hoses are fine they don't suck flat. The system has pressure not that I hooked a gauge to it but when I squeeze the top hose it is hard.

 

Sorry, but you are wrong. the definition of a blown head gasket is just that, the seal between either the oil passage to coolant, coolant to cylinder, or cylinder to oil passage. I have seen different vehicles with all of these concerns. As for what I am mentioning specifically, a small blow between the cylinder and the coolant passage will allow combustion gasses (and heat) into the coolant passages, causing the system to overheat. The excessive pressure in the cylinder will prevent coolant from entering the cylinder on a small leak as he MIGHT (I said MIGHT) have in his head gasket. Again, I have seen this. That is the reason they created the combustion gas tester, to detect small amounts of combustion gas in the coolant system.

He might have a water pump issue, as we have stated, but we also wanted him to be aware of other things to check into as well.