Mattb116097

Overheating, New to the yota forum but I am not new to forums so I have read several thread on overheating and the 3.0. For some reason I can’t find the exact same problem with mine. So here we go. Not getting to temp, so went to change thermostat, none there. OEM t-stat installed. Overheating. Put it on a hill to burp the air out, cap off heat on high. no go. Put it on a hill on ramps until the fluid was spewing out of the top of the radiator. Still overheating. (Not at idle, only while driving) Drove it around a while stopping when it got near the red line. Let it cool then back on ramps to get any air out. Still overheating. Radiator cap new. Compression test good, pressure test good, block test/ emissions in coolant negative. Pulled bottom radiator hose and stuck a water hose in the top flow coming out was comparable to what was going on. Here is the part that I think is different. Radiator cold, 3inches from the top all the way down. Bottom radiator hose ice cold, Top on fire. Swapped radiator same thing. New water pump, fan clutch. No change. Yes the shroud is there. Been to two shops, no help. So, what do you guys think?

dbittle

I would pull the thermostat out and make sure it is opening at the right temperature, in a water pot on the stove.

swampedout

Losing coolant?

Mattb116097

Not loosing coolant, thermostat opens as it should. I think the radiator is air bound but don’t know how to purge it.

dbittle

Could be. Something is blocking the circulation, that's for sure. Radiators not plugged up, thermostat opens properly. Thermostat isn't backwards and has the vent hole like it should?

Mattb116097

Yes the thermostats in properly facing away from the block towards the radiator. Jiggly valve at 12 o’clock. Also, I stuck a garden hose in the top radiator hose going towards the block, and took the thermostat and bottom radiator hose off the bottom of the block. The water flow from the top hose to the bottom exit of the block were comparable. So I don’t believe there’s any blockage in There.

swampedout

Thats a good sign
more than likely youve got air getting trapped under your thermo so when yuour driving thermo doesnt get up to temp n doesnt open.

superex87

Have you checked to make sure the engine is actually getting too hot? Stock gauge is not very accurate. Seems pretty odd with all the new parts you have it's still overheating. Another possibility is the block is full of trash. Previous owner may have used alot of head gasket in a bottle. It does seem you have restricted flow.

Mattb116097

yes the block is overheating. But more so I have fluid pouring out of the Douglas bottle When I let it redline. Once again it had a pressure test done that said it was good. And my garden hose test made it seem that there was no obstruction in the block. I like the air behind the thermostat theory, it makes sense. But how do I get it out? I have used every technique that has been suggested and it hasn’t worked. Tonight I am going to swap the cheap t-stat with the OEM one again fill the system pull the bottom hose block the bottom exit to the radiator, and pour boiling water into the hose leading to the thermostat. Hope it opens and releases the trapped air, and get it flowing

swampedout

The problem is the air will travel up. If you pour into the upper hose, your trapping air under water. Its possible that with the right amt of water and a lot of jiggling it will work.
the thermo should have a small hole to let air pockets pass thru. The positioning of this hole might be your issue. I dont know for the 3.0 how its oriented. If your method involves jacking the front of the truck up, maybe put the hole towards the grill so it is at the highest point. I know for the 22r there is a very specific orientation and people still argue over it. Should be in your fsm at the thermo install instructions.
wish i had a more scientific method but I usually fill up coolant and squueze the hoses. People swear by those rad cap attachments that act as funnels so you can overflow the rad while filling. Never used them but seems worth it at this point if you havent already tried it.

Also, i know this is the last thing you want to hear but check your coolant and oil to make sure theyre not mixing in the block.

swampedout

I agree that the stock gauges arent the best but if they are showing high temps, that is not a standard malfunction. When the gauges go, they will reduce conductivity and give low readings like your motor never warms up.

swampedout

Just reread your post abt jiggly valve. Sorry my memory has very little room these days.
my point remains, however, if youre jacking the front up, and your valve is at 12 oclock, youre pushing air away from it. If 12 oclock is the correct position, probably better to level truck out to bleed air.

swampedout

Also what method for your pressure test?
and how long has this vehicle not had a tstat?

swampedout

Oh and turn your heat on when youre getting air out. Air can get stuck in your heater hoses

Mattb116097

So heat is on full as I try to evacuate air.
Every post I read and video I see has me jacking the truck up to release air.
Have checked the oil daily since I started this process. I know head gaskets on these thing are a problem, but so far there are no signs of that being the problem.
The debate on the orientation is either 12 o’clock or 6 o’clock. I guess the Haynes manual says 6 but the Toyota says 12. The general consensus on this is follow the Toyota manual.
Should I not fill the block by using the top radiator hose that goes back into the block? Is this why I can’t get the air out?
2 pressure test done by mechanics. One I didn’t witness. The other he put a cap on the radiator with a hand pump and a gauge. Pumped it up till he hit what he thought was the right amount of pressure and then released it.

swampedout

Water flow into the block goes from bottom to top. The top hose is the return back into the rad.
in my understanding, the important thing is that the rad cap be the highest point so when youre filling and burping all air will travel up and fully out.
im not quite clear on how youre filling with the top hose but i would reccommend filling by pouring into the radiator.
also, people swear by toyota red coolant. They say the green stuff doesnt work. From personal experience idk, but i use red anyways.

DH4runner

If it is still overheating, id flush your heater core, i also bypassed my rear heater hose to cancel that out, more coolant flow to where i want? Not sure if thats really effective or not. But also maybe a failing water pump?

Mattb116097

Ugh, head gasket. Did another block test today, it took about 25 min but eventually the blue liquid began to turn green. The first block test the mechanic only did for about 5 min. Then retested a few min later for 5 min. This time he tested for 25 min straight.

Jimkola

If you leave a block test on long enough you’ll get color change. Going from blue to green over a 25 minute time period is pretty inconclusive. I remember when we had a tech that was condemning 22R headgaskets way more often than the other 14 techs. Turned out he was leaving the tester in the radiator for a long time. We loved the block tester, but we needed to see a blue to yellow change fairly quickly to condemn a headgasket.
it’s been ages, but I recall the 3.0 V6 was problematic to flush the cooling system. With the thermostat at the bottom it was easy to fill the radiator, but not fill the block, unless you did it fairly slowly so the water could trickle down the upper radiator hose and into the block. Otherwise the air got trapped in the block, and kept water away from the thermostat and wouldn’t allow it to open and circulate water.

2ToyGuy

I don't remember where I saw it, but I read that a good way to bleed air from the 3.0 is to pull the input hose to the heater valve on the firewall. It's the highest point in the system, and IIRC will allow ay air trapped behind the thermostat out.
Just leave it on a relatively leave surface, pop the hose loose, and let the air bleed out as you add water to the radiator. Once you get no more air, replace the hose onto the valve and let 'er run!

I don't know if it'll help, but worth a look...
Pat☺