Mattb116097

So got back at it again today. Took the OEM thermostat out and pulled the springs on the cheap thermostat off left it open and put it back in. The truck will only come to temp if I let it sit at idle. When I drive it gets between a quarter and a third. Also the radiator heats up like it should and the bottom hose is also Luke warm as I would guess it should be. This circles me back to the problem is the thermostat, not sure if it is because of air or what. But I am convinced it is not the head gasket. So now what? I have listened to every idea on how to bleed it and did it. I will go to Toyota and get a new thermostat, and see what else I can figure out. Anybody know of a Toyota guru in CT?

swampedout

So let me ask this:
you idle the engine, it goes up to temp. start driving it goes back down a little. If you idle for a while after driving what does it do? Back to half?
What abt turning the truck off once its warm, then turning it onto accesories. Does the temp gauge go to half then drop down?
you might have a bad temp gauge.
your engine is not cooling down once you start driving it. Thats against all laws of physics. That indicates a bad temp reading. If your engine were overheating, you would not know.
spend 20 bucks and get an infared thermometer.

Its possible your getting all the air out now. If youve done all the tricks, thats taken care of. Its not an impossible task. And if your temp sensor is at the thermo and it reads at half then your good. Those two usually are in sync. If your sensor is up to temp, your tstat should be too therefore it should be opening.

swampedout

I dont see any reason to buy a new tstat. Your focus now is getting a proper reading
but im also not super familiar with the layout of the 3.0. Is the temp sensor by the tstat?

Mattb116097

Against all laws of physics, that’s what I have been saying. It makes no sense to me. New sensor, not near t-stat. It works. The temp goes up from the time I start it to the middle of the gauge then lowered as I drive. Don’t forget I have a wide open t-stat, intentionally as a diagnostic piece. I am sure the system is overheating when the OEM t-stat is in. I can tell by the fluid pouring out of the Douglas bottle as the gauge red lines. Don’t mind buying the thermo gauge just not sure it will help as he sensor is working properly. If you have been following from the beginning then you can see I have done all that can be done and still have the problem. I am completely lost. Nothing makes sense. I consider myself a pretty good wrench turner and have had 6 mechanics look at it nobody can make heads or tails of it.

swampedout

Ok but the fact remains something in your gauge/sensor loop is not working. Your engine is not cooling down while driving. That is usually a symptom of a bad electrical connection somewhere: it can take so much heat then the metal seperates when it gets hot, resulting in a lower reading. You have extra resistance somewhere. My first guess is the gauge coil but you need to bust out a multimeter and a service manual.

swampedout

Just to be clear: you have seen your gauge go over halfway?
an infared thermometer is a point and shoot gun with a 9v batrery. No fancy wiring, no installation. You can really help yourself by getting one and instantly checking temp against your gauge.

Mattb116097

I’m lost in what you are talking about. So there is nothing wrong with the sensor. This all started with my truck overheating. I have literally changed every component of the cooling system. You keep telling me there is a problem with the sensor, there is not. The sensor is reading correctly. I have seen the gauge go from cold to overheating. While it is overheating there Is coolant spewing out of the overflow. The odd part is that the radiator was cold. Pulled the thermostat, everything works as you would think, doesn’t get to temp except while idle. The radiator is warm as it should be. Once again I will get a thermo gun, because I need to add one to my tool kit but it will not help in this situation

Jimkola

Damn.

Ok, one thing bugs me, not finding a thermostat when you went to replace it. I’m assuming you didn’t take it out earlier, so are you a fairly new owner?

I'm wondering if someone else owned it, had a overheating issue, did a poor repair, and sold it. In my case, I found AlumaSeal packed in the water passage in the block going to the coolant drain right after I got it.
You could drain all the coolant and remove the block drain plug under the exhaust manifold and see if it’s loaded up with some sort of quick fix sealant (Bars leak, AlumaSeal,etc).
If every possibility has been explored the next step is to pull the heads. Do one last compression test, and if possible, a leak down test, and record the data. You may need later.

Mattb116097

So, yes new Toyota owner. Yes I believe the former owner got rid of it knowing there was a problem. The thing that continues to boggle my mind is when the thermostat is in the radiator never heats up. When I pull the thermostat the radiator gets warm exactly like you would expect it to. This is what leads me to believe it’s a flow problem, not the head gasket. But I am running out of ideas. Thanks for the block drain plug idea, didn’t know about that. Will pull it and let you know what I find.

5 Fists

But how do you know the sensor/gauge is reading correctly without using a thermo gun and verifying that what your in dash gauge is reading is actually the coolant temperature? That's what swampedout is trying to say, your gauge could be reading wrong. If you're not comparing it to any actual numbers, then who knows if it's reading right?

Jimkola

Well, the OP did mention that when the temp gauge goes into the red the overflow bottle starts dumping coolant. Unless the overflow bottle was radically overfilled when cold, a properly running engine/cooling system shouldn’t dump excess out the overflow hose.
but thermal guns are cheap. Not the worst thing to buy. But unless I’m missing something, with the information supplied I’m leaning toward something restricting flow within the engine or some sort of issue at the heads that may be partially masked by prior repair “fix it” attempts.
im curious if the waterpump that was removed showed signs of rust at some point.

5 Fists

To echo one of swampedouts questions that didn't get answered earlier: Have you seen your temp gauge go into the red? Or the reading stays low and then you lose coolant out of the overflow?

It was never stated that the gauge went into the red and it actually over heated, in the original post you state:

Mattb116097

I also said I’ve seen the gauge go from cold to overheating. I thought that was pretty clear, that it was reaching the red line. When it reaches the red line I have fluid coming out of the overflow bottle. Hence I know the gauge is working. I understand what he is saying, It’s just that I thought I was making it clear that the gauge goes through the full range of motion and has all the signs of working properly. When the gauge is cold I can’t get any warm air when the gauge is redlined I have fluid coming out of the overflow. I appreciate any help from anybody, understand at this point in time my frustration.
now, can anybody give me a reason why when a OEM thermostat is in, my radiator never gets warm. In other words, I believe, the coolant isn’t circulating through the radiator. Even when the truck is overheating. When I pull the thermostat the radiator gets warm and does it’s job properly. Unfortunately without the thermostat doing its job I can’t get the truck up to temperature, which is what I expected. When I find a solution to that, i’m pretty sure I’ll know what the problem is.

dbittle

Yep. Problem seems isolated to the thermostat area. One guy mentioned the water pump might be going. Maybe it can push coolant through the system without the thermostat restriction, but not with it. How many miles on the pump?

Mattb116097

New water pump, that was my first thought as well

dbittle

With this in mind, I put a water pump and thermostat in my 3vze truck today. I took an extra step to drill a .125" hole in the thermostat flange, just to be sure the air can vent from behind it. If the gutted thermostat worked, this might be a next move for you.

old87yota

There shouldn't be a need to drill a hole in the thermostat, as it should already have one in the form of a "jiggle" valve.

dbittle

Consider it to be the next level of escalation above the factory provision. Not too big, but leaving nothing to chance on having an air pocket back there.

Jimkola

I was involved with hundreds of 3vze headgasket/shortblock repairs during the recall. We never had to do anything esoteric to get them up and running and out the door. They were pretty straight forward after you’d done a few. And by the time Toyota opted for the recall the composition of the headgasket had been refined to the point where their longevity was comparable to any other Toyota in the line up.

but back to the OP’s engine.

no external leaks?
waterpump working?
radiator not restricted?
new OEM thermostat?

There’s not much left. Personally, I’d do a compression and leak down test. If the leak down is overall decent I’d pull the heads. If the leak down numbers are close to being no good I’d pull the engine. But that’s me.

superex87

Leak down test is the best way to check for failing head gaskets. Cold engine remove radiator cap and pressurize each cylinder while listening for bubbles. Your overflow should not be dumping fluid when the truck over heats unless it is severely overheating. It sounds like there is a very good chance that someone used a stop leak product on it and has restricted the flow/ heat transfer in the cooling system. At this point the only way you will know for sure is to pull the heads and inspect for damage.