DubJunkE

I can't quite figure out why my 4runner is overheating not too familiar with this motor yet. But Im looking for suggestions before I dig into the waterpump. It's not the fan, fan-clutch, thermostat or radiator cap. It overheats after a few minutes of driving and the heat doesn't work so Im thinking the water isn't circulating into the heater core, also the coolant in the reservoir isn't being circulated either, which I think would point to waterpump but wanted some advice before I buy that and start taking stuff apart. Thank for any advice in advance.

gwhayduke

First make sure that it has coolant. The 3.0 is notorious for blowing headgaskets and leaking coolant, either outside or inside the engine.

shamrockmac5

If not the thermostat then try flushing the radiator it may have a blockage. Be very careful not to drive it like that especially at this time of year. If you blow a head gasket you'll be over a barrell. The more you read about these things the more you will learn that above almost all else 2nd gens are notorious for weak head studs/bolts and flimsey head gaskets. Also if you are due for a timing belt soon then don't be afraid to do that at the same time you get the waterpump replaced.

DubJunkE

I know about the headgasket troubles so Im being real careful not to overheat the engine while troubleshooting, I'll try the radiator flush then probably do the waterpump if that doesn't help anything. Thanks for the quick replies if anyone else want ot chip in let me know thanks

gwhayduke

The radiator flush is a good idea...but not until you swap out the thermostat. If the thermostat is stuck closed, the flush chemicals won't get to the engine block or the heater core. Thermostats are cheap and if I remember right, I replaced mine without too much trouble.

DubJunkE

Thermostat has already been replaced along with broken fan, fan-clutch etc.

radrex

Didn't put that thermostat in backwards did ya?

DubJunkE

No, paid extra attention to make sure that didn't happen

DubJunkE

Feel free to chime in if you have any other suggestions, thanks again

Babypig

Could also be that the heater core is blocked. Has any work been done to the engine lately? Could be an air bubble. Other than that a malfunctioning water pump or bad gaskets are the other logical places to look.

Nam

Oh well,

Does the water boil up and spit out of the reservoir? Also try to run the engine from *COLD* with open radiator cap. If you see bubbles coming up...not a good sign.

If you know for sure that water is not circulating, two things: water pump or blockage.

Good luck.

Nam

934rnr

Have you had anything done lately like the headgaskets or anything? I had mine put back together with the headgaskets on backwards once it overheated after a few min everytime.

gwhayduke

I've never had a water pump stop pumping...unless a belt broke. They usually fail by leaking around the seals. The air bubble is plausible if you ran it low or drained your system lately.

Did you use a Toyota thermostat or an aftermarket? If it just started happening after installing the thermostat, it could be defective.

I think at this point I'd install a Prestone Flush Kit, get a couple bottles of Prestone Super Flush and go to it. Expecially if you've never done it before. Drain the antifreeze first and dispose of it as hazardous waste...It's toxic to critters and you don't want it seeping into your aquifer.

If that doesn't work, I think you're gonna have to tear down your system, get the radiator professionally flushed at a good radiator shop.