Overheating issue

[drguitarum2005]

I was sitting in the drive thru of my favorite local place and I was idling for a good 15 minutes. As I pulled forward to the window, the CEL caught my eye and I looked at my temp gauge and it was way up in the red. I shut my truck off, rolled down the windows and turned the heat on full blast and watched it slowly go down. I needed to get back home so I was going to limp home but when I turned the truck on and gave it some gas to get going, the temp dropped down at about the speed the gas needle goes up when you get a full tank. The temps were fine after that.

Since this weekend I've been sort of hearing this watery sound from up near the windshield. It sounds like water going through pipes and it happens when im accelerating in first gear. it may happen in other gears but i can't hear it over my truck.

Also, since I got the truck, i've always had a slight rattling sound on acceleration, specifically when I'm at low rpms in any gear and pushing hard on the accelerator. some days this sound is very very loud, like shaking a plastic easter egg pull of pennies. i don't notice any performance issues and it goes away with some driving, but im beginning to think maybe this is linked to the overheating. i had my water pump done at 80k and im at 95k now. what are your thoughts?

2000 tacoma 3.4 5spd

[drguitarum2005]

a little more information:

coolant level is good, no obvious leaks, no puddles on the ground, ac wasnt running, and its about 50 outside. fan is running, belts looks ok...

[DHC6twinotter]

Air in the heater core maybe? Not sure about the Tacos, but I've read plenty of threads where people hear gurgling sounds from their heater cores on the 2nd gen 4Runners, especially when accelerating. Mine does it a bit sometimes.

Don't know about the pennies in a easter egg sound though. :headscratch:

Just my $.02.

[drguitarum2005]

it may be more of a loud clattering than exactly a pennies in an easter egg sound... ill look into this heater core thing...

[mkgarrison5]

how do you fix air in the heater core plus how does it get in there to begin with??

[MTL_4runner]

Get your cooling system pressure tested and see if there's any leaks. I say that since a waterpump leak may start out slow and then get worse over time and usually dry up before anything hits the ground. You may want to pull the timing cover off and have a look down inside just in case to be sure there are no visible leaks in there either.

Was the waterpump an OEM part?

[drguitarum2005]

ill look into a pressure test on the cooling system. i had the water pump done with the belts at 80k at a dealership so yeah, its an OEM part

[SLC97SR5]

I had a similiar gurgling sound while warming up my 4Runner after work. I parked the 4Runner with the heat valve / mixing valve in the halfway position and then went to work, when I came out 10hrs later I fired up the Runner and let it idle for 2 minutes. During the initial warm-up I could hear water running in the dash, I almost expected my foot to be wet!

Here is my theory: I parked the truck at normal operating temperature; 193* to be exact. My heater valve was in the middle position. The Outside Air Temperature was approx 50*. During my shift the OAT dropped to 35*. My thnking is that the heater valve created an air pocket and during the evening cool-off coolant was siphoned into the expansion tank thus being pulled out of the heater core and as the OAT dropped it was never pulled back into the engine. So, upon start up there was a coolant deficency in the core.

Is this wishful thinking or 'am I in for a WP replacement.

[Ian Rogers]

slow down there. When the truck is cold all the water from the water pump is traveling where ever it can, until the t-stat opens. Once the t-stat opens the coolant can travel in to the radiator and the noise under the dash should stop, because there is not the same amount of volume traveling in the heater core.