gn86r

i was sitting in a drive thru tonight and noticed the temp gauge on my 99 4runner sitting right below the H. what i did notice it that if i rev the motor up, the temp comes down. also i noticed that the coolant resevoir was almost full, my rig has about 81k miles on it and im thinking it could be the water pump going out on me, or possibly a stuck thermostat.. any ideas?

Chi_San

I almost thought you said 'drive in movie'. I was like 'WTF? o.O;;; Those don't exist anymore.' Then my tired brain realized what you were saying.

Check the fans in the front of the engine. Are they spinning? Do you have lots of bug remains in your rad clogging airflow?

Does the 4Runner have belt driven fans or Electric? Our T100 has a belt fan, and I can hear it kicking into high gear when the AC is on or it's hot. If this isn't happening for you, it could cause the overheating.

I'd check the water pump, and make sure your Alternator is putting out enough juice. I assume you have a voltmeter built into your dash? If your alternator isn't putting out enough juice, things might stop running, and then you'd be running without a water pump or something necessary like that.

A friend of mine has an uncle who owns a repair shop. He has said on many occasions that after an engine overheats once, it will keep doing so over and over until it's dead. So keep an eye on that temp gauge. Since you had no load on the engine when it started getting up there, I'd say it's most probably a stuck thermostat.

MTL_4runner

First of all check the coolant condition and level (has the coolant even been changed?.....not likely the problem but it is worth doing) I am pretty sure that would be a faulty thermostat but you would need to pull it out to check and in that case just replace it to be sure. It is possible that it could be the water pump but it would need to be seriously corroded to be that bad (coolant condition should tell you this).

gn86r

i actually flushed the radiator about 3 months ago with the red coolant and waterwetter, so im pretty sure that the coolant is good, not to mention the coolant was clean to begin with. im betting on the thermostat, but at 81k its about time for the t-belt so i might just go ahead and do it now.

gn86r

okay did the thermostat didnt help, any other ideas? i might just have to do the t-belt and water pump soon.

Fink

Actually they do, theres a really nice one just down the road from me...those are the times I wish I had a pickup..or atleast a 4Runner without the woofer box in the back

Just thought I'd add that in there...

Fink

My99

I had a car that would overheat (well come close) on occassion. I took the radiator out and had it cleaned at the radiator shop. Cost about 50 bucks. They said it was about 90% clogged. After that never had any issues.

AgRunner06

I'm not sure if this is possible but it might be if you turn your truck off.

Wait until the vehicle gets good and warm, then turn it off. If you can, reach down and start feeling on the radiator. If you feel any cool spots, those are places where it is clogged. I'd check the radiator first before doing the water pump.

Good Luck

gn86r

okay, still no idea what could be causing this to overheat. it doesnt overheat while the rig is moving. is there an electric fan that comes on with the a/c?

RobT2k

Only if you installed an aftermarket electric fan. The stocker runs off the engine. Did you check the radiator? I've had the water pump/tstat/t-belts serviced and have never had an overheating problem. I just rolled over 100K on the odometer too! It is so nice to wheel in the middle of the 100 degree desert with the AC cranked and have the temp gage at less than half.

Ric

hey all, mine is now overheating, just noticed it tonight, its a 99 4x4, im going to try the things listed, but anyone have other ideas ?
Ric
UPDATE : fan works, radiator is NOT clogged, fluid is full and red in color, no cool spots on the radiator... any ideas ?

User 051420

Why are all these newer runners overheating?!?!? I have 170k on my 97 and it's always less than half on the temp gauge. Wheeling with A/C or not.. Never overheats!

Does your 99 have an extended warranty?

Ric

nope, i got it used, 2 years ago, mine has about 130K miles on it.

gn86r

i still havent figured out what was wrong with my truck yet, but i think that the thermostat housing is leaking, im gonna seal it up tomorrow and see what happens. hopefully it was just that and i can drive my truck again.

Ric

well i got a new thermostat, as i was putting that on, i noticed, on the back side of the radiator, was covered with dirt, , got that clean, new thermostat in runnin like a yota, lol

BruceTS

Pressure test your system, that will tell you if you have any leaks

Check your clutch fan to see if it has enough resistance; with the engine of spin the fan by hand, if it spins freely the clutch is worn out, but if there's a lot of resistance, it should be good.

since you said it runs cool when moving, I doubt your radiator or thermostat has a problem

at 81k the water pump housing will probably have minor leaking and replacing the pump or re-sealing the pump would be a good thing. If you gonna replace the water pump, replace the timming belt at the same time.

candyeman

Hi,
i had all the cooling Essentials replaced on my '99 4Runner,just under 60 thousand miles on a completely rebuilt engine,and i started devolping a serious overheating problem.
truck was running fine after everything was replaced,but two weeks later ,my Runner started overheating again,while sitting in a Drive Thru!
I took it back to the shop, and this time they told me they pressure tested it ,it could possibly be a blown head gasket or cracked head .

Nate08

Check the themostat, that happened to my friends Tacoma.