so car is overheating (goes to the 3/4 bar, the bar before the red).
it began when the A/C was running so i turned it off, but now its going to the same spot regardless of the a/c. Ambient temp is somewhere in the 100's

i have checked to make sure both of the fans are working, but when looking between the radiator and the engine there's some water sitting on the bottom. (not sure if its from the a/c or if its from something else).

any ideas of what it could be?

 

were both fans working ? I just replaced my fan motor because the driver side fan was going out.. I had to keep tapping it to kick back on.. The right side fan blower will keep it from going to full overheat mode.. I believe it was around the 3/4 hot range unless i got on the hwy and it would cool back down?

 

If you were thinking of getting an OBD II reader like a scangauge II or similar product that can show real time metrics, then now might not be a bad time to get one as it might help with the diagnosis. The water temp meter on the dash is not an accurate measure: if the temp falls within a specified normal range, engine management will show normal with no deviation at all (they don't want to worry you and cause a potential trip to the dealer). Only when temp gets far outside the normal zone will it deviate (aguably too late, and useless for troubleshooting). An OBD II reader will tell you the true water temp in degrees so you can see small fluctuations. (Any excuse to buy a car toy!)

That said, there are usually only a few things that cause overheating. Not enough coolant in the system (perhaps due to a leak), insufficient cooling on the fans/radiator, and an old/lazy thermal valve.

If you have low coolant then turning the heater onto full power (highest heat, highest fan) will cause only semi-heated air to come out. (This is a generally good thing trick do if you notice an overheat situation while driving - it can potentially save your engine - although it works less well for low fluid conditions.)

A broken radiator fan is pretty easy to spot - it's not turning when it should. Could be a relay, wiring or the fan itself.

The thermal valve is what moderates the engine's water temp - there are two coolant loops, one that's like a short-circuit bypassing the radiator and one that goes to the radiator for cooling. As cars age, the valve spring gets lazy and won't open the valve all the way in really hot conditions, causing a partial bypass on the system's full cooling capability. If you only get overheats in the hotter summer days and otherwise things are ok, it might be this valve that needs replacing. In this case, the OBD reader will show that as ambient temps rise, the water temp (which usually sits around 190F) creeps up from that number during accelleration and takes longer to settle down to normal operating temp. As time goes on and the part progressively deteriorates, this gets worse and more exaggerated.

From your description, seems like it could be either a fan or the valve (rule out coolant level and fan first, since they're easiest to detect). Try not to let your engine get into the red again - kill the a/c, roll down the windows, open the sunroof and turn on the heat and fan to max and tough it out as soon as you notice the temp climbing - a little discomfort is far better than a destroyed engine.

 

Theromstat needs to be changed. Gasket is a rubber ring so get that when you replace the thermostat. will need to burp the system after you do this to get all of the air out of the system. the screw is on top of the thermostat housing.

 

Hey thanks for all the help!

Turns out all the coolant dried up or leaking (will check tomorrow morning). When i took off the cover on top of the radiator/overflow tank it had a bunch of crusted up fluids. I found a buddy with tools at school and was able to make it home. If i find something leaking ill let you guys know!

 

The coolant has to be going somewhere. It is very likely (hopefully) that the fluid you saw pooled up at the bottom of the engine bay was from a coolant leak from a hose or other source. If the coolant leak isn't external, then it could be internal, which could be a headgasket etc. Unlikely but possible.

 

it looks like it came thru the top? the cover was full of this white flakey stuff and it had also pooled on the the reservoir top. im guessing it evaporated away (it was 110+ in LA :'( )

 

Here in AZ, the coolant bottle will evaporate dry during the summer, as it's like 108F every day w/ 5% humidity! Keep an extra bottle of coolant in the garage. Fill up the bottle to the line and inspect every week. The level should stabilize and remain constant. If you see it slowly drop after each drive, you have a leak somewhere. If you suspect a leak, you can have the cooling system pressure tested. I once had a leak in a hose on my 4runner that would only leak when the engine was cold. Since I was driving 20+ mi on every trip, I'd just see coolant splattered all over and the bottle level dropped, but I never saw anything leaking until after a short trip to the gas station on a cold engine, where I saw a puddle of coolant under the car. Turns out, when the engine is cold, the cooling system is pressurizes until the coolant becomes hot enough so that the valve in the radiator cap opens. This allows hot coolant to expand into the overflow bottle. But before the radiator cap valve opens, the system is under maximum pressure. This is when leaks are more likely to occur. Once you shut off a hot engine and it cools, it'll suck back any coolant it needs (unless the bottle is dry).

 

hmmmm well this morning i opened the cap, the coolant level dropped so i refilled it with distilled water to the top. checked the reservoir, which was also empty, and filled that up with distilled water. I ran the car, it ran alot cooler than normal (not in the middle but the first mark below) it seems to have fixed the overheating problem i had,

but the question i have now is i filled the radiator with a quart of water. Is that normal for sitting over night?

@Jim Chow how do you test the cooling system pressure? is it something that can be DIY or do i need a shop to do it?

 

Your radiator cap is the device that vents at a given pressure. As long as there is no leakage of fluid the system will operate properly. Be sure you use a proper radiator cap as different cars sometimes has a difference cap relief pressure.

 

What year is your car? If '04+, you should refill the bottle and radiator with the premixed Toyota super long life coolant (yellow cap on the black bottle), NOT the Toyota long life coolant (red). You shoudn't be losing a full bottle's worth overnight. Make sure the cooling system is burped well (park on a slope, remove radiator cap, run engine @ 2000rpm to warm it up. Any bubbles of air in the system should exit through the radiator. Turn off engine, top off radiator w/ coolant, fill bottle to the full line. Drive around and check the next day. After the engine has cooled down, check the coolant level. The level in the bottle should be somewhere between the full and low marks while the radiator should still be full.

The way to pressure test the radiator is to get one of those pressure testing devices (a shop can do it in a snap). It's like a radiator cap with a pump on it. First thing I would do is make sure your thermostat and radiator cap are operating properly. In fact, I would probably replace them, as they are only like $15 each plus the thermostat grommet. I think the thermostat is a 82C one.

 

Thanks for the reply Jim,

Its a 2001. Whats odd is after the first day of re-filling up the radiator/reservoir the level hasn't changed. The car seems to run a bit cooler than before, but later this weekend ill take it by a shop to have the radiator tested and replace the thermostat.

 

Make sure they do a pressure test of the system. Sneaky leaks (radiator tank seals,weak hose clamps and such) that only occur when at full operating temp and when the system is pressurised may not show up with a quick visual check,but will weep when the system is pressurised and will show where you've been losing coolant from.


Justin...

 

Apperently my ls430 01 starting to gove me over heating problem appernetly the fans are working fine thermostat is fine no leakage also so getting difficult to understand what the problem is only seems.to happened when the ac is turned on and when i turn on the heater it cools down to normal temperature where m at is 108 f

 

Sounds like a water pump issue if you noticed water between the radiator and front of engine, or perhaps your radiator has sprung a leak.