Toyota Tacoma 2RZFE Overheating @ idle?$%$#

[kitster]

I have a 97 Tacoma thats overheating only when idleing. I changed & flushed the coolent & replaced thermostat. This did seem to help a little. The belts and fan clutch & shroud seem to be fine. I also checked to make sure I wasnt getting a pinched hose. I let this truck sit idle for approx 45 min and It will start to heat over normal. The only thing that seems a little weird is that when at idle with cap off I see no coolent movement. If I idle up a little its moving. My question is, could this be the water pump fins getting worn away or maybe not enough force to push coolent through the thermostat? It just seems like at idle I am getting no coolent movement. Also if it starts to go over normal heating range a couple of taps on the gas and brings the temp right down to normal. Any thoughts on this would be appreciated.

[bearcat329]

sooo! after sitting and idling for approx 45 minutes, the engine begins to overheat? just out of curiosity, why would you idle an engine for 45 minutes?
anyway, if there was a real problem, it'd overheat much sooner, you can try some redline water wetter, it's formulated to aid in the transfer of heat.
and you can always replace the water pump if you think it may be the culprit.
but if it was my truck and fuel price's being what they are these days, i'd turn the thing off soon as anything related to the operation of the truck was no longer needed.
not sure if this'll help, but good luck
Rick, Ore

[Shredhead]

First off good job on trouble shooting second sounds like Your loosing the pump, the pump is a lot easier to replace on a rear wheel drive than front wheel.

[kitster]

This last weekend I decided to do a little more investigation. Since I only drive this truck on weekends I can mess with it a little @ a time. I did a compression & leak down test on the motor. I was getting a little over 170 PSI on all 4 cyl. I assume from those numbers I am not leaking from the head. In my attempts to bring the temps down I pulled the thermostat out. This did make getting up to operating temp longer. Still seems like its running to warm for not having a thermostat. I am ordering a new water pump. I will slap that on and see if that helps. I will keep posting till I resolve this issue. I am sure someone will benefit from me taking this engine apart until I get this problem resolved.

BTW::thanks for the responses I appreciate it.

[Flash75]

When you say it's overheating is the gauge up to the red zone on the gauge or is it just above the normal reading? If it is not up to the red zone and is not blowing coolant out it isn't overheating. It's normal for most vehicles to run a little hotter at idle, it's also normal for them to cool down when the engine is speeded up because more coolant is circulating. The thermostat controls the lowest oprating temperatue and unless defective, removing it will not correct overheating. If you really think it's overheating use a cooking thermometer and see what the actual temperature is at idle. I have never heard of a water pump wearing out the impeller blades. I don't think replacing it will help. It doesn't sound like you have a problem unless it really is getting up to or near the red zone. BTW, most modern gauges move in segements rather than showing actual temperature. It may take 10-15 degrees change to cause it to move and the movement will be enough to really notice. If it really is overheating I wouldn't rule out the fan clutch. A fan clutch can cause the fan to lose rpms as it ages.

Clifton

[Shredhead]

That's true but it sound's like he knows his truck and water pumps don't alway's just go out, it took about 3 months before my pump went completely out till then it just got real hot in idle and ran fine while going down the road

[kitster]

I know its been a while but I thought I would post the resolution to my problem. I called a friend that worked @ Downey off Road racing. They are like the authority on Toyota high performance. I explained my problem and they thought I had some sort of blockage in the block causing the motor to run on the warm side. I did what was recommened and backflushed the system. I noticed that there were a few little chunks that came out during the backflush process but not enough to create a blockage. After backflushing it did run cooler and took even longer to hit operating temperature. Truck still seemed like it was running too warm after a grunge run up a long hill. I called Downey back & they thought it was also the fan clutch going bad. So instead of just buying another clutch I decided to bulletproof this problem and buy a flex-a-lite electric dual fan setup. I had a plan to go ahead and install this part but I kept thinking I should do it right and replace the radiator too since I would have to tear all of this apart to do it. I went ahead and ordered my new radiator from radiatorbarn.com. I installed this 2 days ago. I still had in mind to install the new electric fan system but thought I would get the radiator finished first. So this was the total solution to my problem. I started the truck /w air conditioner on full to bring the temp up faster. Let it run for a solid 45 min. The temp gauge never went up. I mean it was below the cold line & probally never got up to 150 to bump the needle. Even thou this resolved the problem I am still putting on the fan system to further aid in cooling. I still need to put the thermostat back in becuase its running so cold now that the temp gauge won't move. So there you have it a bad Radiator. Problem Solved!
I am a little dissapointed that this was the fix to the problem becuase every year I have flused this system with distilled water & prestone 50/50 mix. To think that the radiator had a blockage bad enough to make the truck run warm blows me away. If I had abused this cooling system I would understand but since the truck was brand new I flushed & changed every year. Ok I am finished spouting off about it. But for those of you that start to have a problem dont leave out the radiator. I think the radiator is a weak link in this years design. Good luck peace out!

[Flash75]

Thanks for letting us know to solution to the problem.

Clifton