This last weekend I drove my 4runner to the local ski resort, when I got off the main hwy you start to climb about 2mi hill to the top, half way up I notice the gauge starting to climb also. I turn on the heat full blast to help until I could pull over. When I finally pull over I pop the hood and notice my p.s. header w/ wrap is on fire, so I throw some water from a 20 oz on it and put it out. I let it sit for about 10-15min. get back in and its fine. Drove it back home several hours later and everything is fine even doing 70mph down the interstate?

Thermostat, water pump, radiator and hoses have less than 10,000mi. on them
It holds 13lbs pressure but slowly drops after 3-5 min. How long should it hold the pressure? Radiator still has same amount of fluid in it.

Any ideas, thanks?

 

Wow, your header wrap was on fire? I guess that's a pretty good sign of high exhaust temps. What was the elevation change for the day when that happened? Maybe the ECU didn't have time to adjust the air/fuel ratio.

 

DON'T WRAP HEADERS!!! I can't stress this enough. I was just speaking with Stan himself, of Stan's headers in Washington, about 2 weeks ago. I specifically asked him "what do you think about wrapping headers?" His answer was 'don't do it'. He said that no header manufacturer will warranty their headers if you wrap them, it cooks them and they will crack, and the heat trapped under there is so high that it can catch fire, as you saw today. Unwrap those headers for sure, if you are really having heat issues the best solution is to get them ceramic coated, that is the ideal coating for headers.
If you are coming too close to your starter, you can wrap the starter in a heat-resistant blanket, which is what I have done to protect it, just don't wrap those headers anymore. be careful

 

As far as the water temp, if you're overheating in the winter you might really have problems when the weather gets hot. I'd install an aftermarket water temp gauge (the factory gauge is little more than a fancy idiot light) Back off the speed if you get above 230 degrees F for the water temp, the 3.0 headgaskets can't handle overheating. BTW 230 F still shows middle of the gauge on my factory water temp gauge! If your dash gauge was showing over the middle of the range you were likely well over 240 F.

 

One would think that it should hold pressure as long as it is up to temp.

 

Drop a gear and Back off the speed if you get above 230 degrees F for the water temp until it levels out temp wise and when you get to the top if it is still hot drop it into nuteral and hold the rpm's up around 2000 until you see the temp drop down to a reasonible temp and then check the water level add as needed.

 

fan clutch?

 

mt goat: not sure about the elevation maybe 3000ft and about 50degrees out
Taiko: I think I'll do that, thanks! Any ideas on how to get cooler air into the engine bay?

Azusa: my uncle said the same thing, but Im not sure how it works or how to check it.

 

snorkel time! will suck in ambient air temps instead of under hood temps

 

re: cooler air in the engine bay, look into the thermo-tec brand of wrapping, don't wrap the headers, but you can wrap everything else, like plug wires, alternator wire, you can wrap the intake! Some people have seen gains this way, making the intake air cooler. they make a very nice 'lace-up' style intake tube thermo wrap here:

 

Yes, but if I get a snorkel Ill want to take the lake to get to work j/k and it might look goofy since its completely stock, but good idea!

Taiko: supposedly blocks 98%... interesting, I'm gonna look into it.

 

Sounds like a fan clutch to me.

My needle would always sit dead center but whenever I drove up a hill with any substantial grade it would start creeping to the red zone. I could even sit in traffic with AC on, cruise at freeway speeds and hit 4 wheel trails in the high desert without moving the needle.

I tested the fan clutch per the Haynes manual but I couldn’t determine if the clutch was bad. I just decided to replace it because I verified everything else with the cooling system was good and it was 69 bucks (with a lifetime warranty) at the local Auto Zone. Sure enough, after replacing it the heat issue went away.

Here is a decent fan clutch article:
http://autorepair.about.com/library/faqs/bl107a.htm

 

Is your coolant low?

I had a similar issue...going up a logging road on a mountain I started to overheat, I thought I better turn around. Going down the heat gauge went back to normal, so I decided to go back up. Got farther up and then it overheated again, came back down it went back to normal all the way home.

Waited till it cooled off and saw my coolant was low, so I assumed that the incline caused to coolant to flow to the back of the rad and make the truck think it is lower then it is. What I am getting at is if you looked at the coolant in the rad when the truck is facing up hill it would look lower. And if you looked at it facing downhill it would look full or even leak out. Know what I mean?

 

killbillLA: Sounds exactly like what mine is doing. Im gonna look into it, thanks!

toyotatom93: I see what your saying, I made sure before I left the coolant level was normal and it was fine when I got home too.

 

Keep us updated

 

And where would you go about installing this gauge?

 

You mean the sender? I put mine in the upper rad hose:






The gauge you can put lots of places, from as simple as sticking it in the glove box to a fancy gauge pod.

 

Have to agree that a good temp gauge is valuable to have. For temp gauge placement you aren't learning much in that upper hose.
I don't know about the 3.4, but on the 3.slow there's an alum block on the back of the manifold which you'll drill and tap for the temp bung.
Same block has the stock temp sender in it.

Sounds like very high EGT is baking the motor.
What are you running for timing advance?
Have you checked the CAT (a slagged CAT will also cause overheated exhaust.) You better be careful here, High EGT can melt pistons and do other damage too.

 

Actually its fairly accurate there, as long as the t-stat is open. I've compared it to the OBDII readout from the ECU temp sensor and its always within 5 degrees of that after the t-stat opens. The upper hose is the flow straight out of the engine for both the 3VZ and the 5VZ.