I understand that the A/C is supposed to shut down if the 3.0 gets too hot. That is what is happening with mine. The temp gauge only has to get slightly to the right (hot side) of the middle causing the A/C to turn off. The thing is, for the first 150,000+ miles once the engine warmed up that gauge was rock solid -- it would stay slightly to the cool side of the middle no matter what, summer, winter, whatever. When the shop did my head gasket, the first thermostat (from NAPA) didn't work right, so they replaced it with a genuine Toyota thermostat. Since then, once the engine gets up to operating temp, I often notice the gauge moving slightly from left to right (cool to warm) across the middle. No biggie, except now that the heat index is 115 and I'd like my A/C to stay on! But I don't think it's just the extreme heat causing this, because it shut down the A/C a week ago when it was only in the 80s. So . . .

Could it be that this thermostat isn't doing its thing? Or is it (as the shop mechanic guesses) that it's my water pump which was last replaced 100,000 miles ago? I don't have the dough for a water pump right now, so would you guys think I should go ahead and replace the thermostat just to see if it helps, or would I be wasting my time?

 

Wow, no takers?

 

i have the same problem, just it likes to go all the way to the red sometimes, at idle... for extended periods of time.

 

Today while driving the temp gauge went higher, about midway between the center and Hot. After a while it would come back to normal, then a few miles later it would do the same thing. Maybe the water pump IS about worn out. I'm going to have to find some $$ somewhere...

 

you test your coolant mixture? or even if there is enough coolant? never worked on a 3.0 so i dont know how hard it is to take off the belt from it to see how free the WP spins itself.

 

Could be the radiator,wp,block and heads stopped up with stop leak,air locked,Faulty OME T-stat.I have experienced them all!BTW have the rad cap checked also.

 

well the person who had my truck before me used stop leak. in the last 3 years i've just about got all of it out... atleast i think. that stuff is horrible. definitely make sure that you have as much water as it can stand, start the truck up with the radiator cap off and fill till it wont take anymore then rev the motor a few times by hand and see if you can put a little bit more in it. believe it or not, a cup or two of water or coolant will help drastically on these systems. especially if you have the auto like myself. some other things you might check would be your air dams, try to keep them sealed up against the radiator as best possible. however, it does sound like your waterpump is on its way out. while you are in there replacing the water pump you should go ahead and replace upper and lower hoses, thermostat, and timing belt. be sure to check the timing belt pulleys for any trouble. Tim.

 

The coolant mix checks out fine, and the cooling system is topped off. The fan clutch is relatively new, and seems to be working fine. Last week, if I didn't run the A/C the temp stayed pretty much dead in the center. But over the weekend it climbed up between the center and Hot a couple of times, even with the A/C off. So it looks like I won't be able to put this off. Thanks for all the ideas.

 

I had the waterpump replaced, they say that they "burped" the system real well . . . and guess what? It did it again this morning.

I left home, drove a couple of miles and the temp came right up to normal. So far, so good. I drove about 4 more miles and the gauge began to climb (the A/C shut down, but that's the least of my concerns now). It went about midway between normal and hot, and stayed there for about 3 miles, at around 50 miles per hour. I pulled over for a minute, gauge stayed there so I resumed my commute. Within 2 miles it returned to normal, and STAYED THERE for the rest of my commute, about 12 miles of start and stop, and up to 55 miles per hour. What the heck is going on with my cooling system?? Did they not burp it enough -- would an air pocket cause this? Any ideas? This is driving me crazy.

 

So before the headgasket change it never overheated? And now after replacing the HG it overheats even in 80 degree weather? Is that correct?

 

Yes, that's right.

 

My guess is they got the gasket inverted and blocked off some cooling passages. Do a search, I remember reading about some guys having that problem. IIRC one guy have gotten like 2 left bank gaskets by mistake so the right head had a left side gasket and it blocked a major cooling passage. But I'm just going from memory here, so the details may be backwards.

 

Here's one thread you should read:
https://www.yotatech.com/forums/f116...hh-help-94261/

 

Thanks for the idea and link, mt goat. If that would be the problem I know these guys would fix it -- it's their responsibility and they've always been pretty stand up. But, if that's the case wouldn't it overheat all the time?

 

The first thing I'd do is install a real temp gauge, those factory gauges disguise the actual coolant temp by having a non-linear scale. They are made to stay smack dab in the middle of the readout through a large range of temps. Mine doesn't move from the middle at all until the coolant temps get over 235 degrees F. So when you say there are times that you don't overheat, keep in mind that the gauge is misrepresenting a temp of 230 degrees F as cool and perfectly normal while a temp of 240 is over-heating. IMHO both 230 and 240 are too hot.

 

Any good space to do this? I'm thinking about doing that since I have everything apart.

 

So you're saying that it could be running hot ALL the time but my gauge isn't showing it.

 

correct.

And if there is one thing Dale knows....its running hot. Read his buildup thread if you dont already.

 

Well lol, lets say "sometimes" it could be running hot and your gauge just shows normal. Basicly the factory gauges are just a small step better than an idiot light. Kind of a fancy idiot light, "fancy" in that it shows too cold or too hot where an idiot light would just show too hot.

Ignorance is bliss and appearantly Toyota wanted its drivers to be blissful.

 

We could fill a whole thread with that question, but one idea I've used is the glove box. Just have to open it up to see check the gauges. Start a new thread and I'll post some pics of all my gauge locations.