My Lexus Wont Stop Overheating!

My 04 Lexus Gs300 WONT STOP OVERHEATING! I brought this car from somebody… I Was Told IT WASNT NOTHING WRONG WITH THE CAR! I Test Drive it… And it seem to be running well! Later that night it began to run HOT! I took it to my personal mechanic… He did a full tuneup, changed the spark plugs, changed the oil… He told me the car needed a fan, new wiring and a new thermostat… That is what’s making the car run HOT… I went to O’Reilly’s brought a thermostat for the mechanic to put on and it was STILL RUNNING HOT! So we took it off and it was running normal temperature for a long time… I will run it til a day and the half before I would need to add more water/coolant to it… Because I didnt have the money to spend on the parts… Just recently my boyfriend dropped me off at home the car was running hot… He didn’t stop to put any fluids in the car he said it cut off on him… He got the car towed home… Started it back up… Now it’s running but it’s running hot more then usual… No I dont think it’s the heads because there’s NO TYPE OF SMOKE COMING FROM THE BACK PIPES!

That means you have a leak. You also need a better mechanic. On a 15 YO car the radiator may very well be restricted with scale and rust.

The car could have had cooling system problems before you bought it, but maybe it didn’t… I doubt knowing that is going to make a difference going forward. I’d bet you can’t get a refund, regardless, right?

How long ago and how many miles ago did you buy the car?

The car should not have been used any time after it showed the slightest hint of running hot or when the slightest bit low on coolant. To do so can/will cause permanent and/or catastrophic engine damage.

After it got towed home, did you refill the cooling system with the proper coolant/water solution before restarting it? No coolant = no steam out the tailpipe, but if you’re very lucky the heads/head gaskets have survived. Although other parts of the engine could have been compromised.

Money or no money, this car should not be driven again until a competent professional mechanic has properly diagnosed and repaired everything pertaining to overheating. I’m sorry if that is not the answer you wanted, but it’s all for your own good.

What about the radiator fan and wiring? If you are driving the car with an inoperative radiator fan you may damage the engine before long.

Bringing a mal-functioning automobile cooling system up to spec is sort of like figuring out why your garden hose is leaking. Or the roof on your house. Could be multiple causes. In other words, solving this problem is gonna take some time and patience. You’ll have to have your shop fix the radiator fan problem, put the thermostat back in, and solve the leak problem. Or at least determine what it is that’s leaking. A cooling system leak means the cooling system won’t hold the correct pressure, which means it is almost guaranteed to overheat. The pressure is an important part of what makes the coolant do its job. Also, running a modern engine like yours without a thermostat installed is looking for trouble; the thermostat determines what % of the coolant flows through the engine vs the radiator. If the coolant is mostly going through the radiator, then there may not be enough coolant volume flow going through the engine, which could damage the engine. Occe you get all that stuff working correctly, if it still overheats, post back. There’s more ideas to try.

In the meantime keep the coolant level topped off daily. And if the engine starts to overheat, but not into the red zone yet, you can sometimes get it back to normal range by turning on your passenger compartment heater to max heat, max fan speed. If the coolant temp goes into the red zone, immediately pull over, turn off the engine, and tow-truck the vehicle back to the shop. This could be a relatively minor problem, so don’t let it become a major $$$ one.

You said your boyfriend was driving the car and it “cut off on him”. If this means the engine stopped from overheating, major permanent engine damage may have already occurred. Do not run this engine again. Have the car towed to a shop.

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This is a very serious condition that you are dealing with… and if it isn’t now, your current use of the vehicle will indeed create a very serious condition.

Cooling system problems are not an optional “I will do it later” type of issue. They need to be resolved immediately before you overheat the engine and warp the cylinder head and or blow a head gasket…all of which may now already be one of your problems currently.

Do you have a coolant leak? Where is your coolant going? If the coolant level ever drops…you have a serious problem that needs immediate attention. There are many reasons for this… you cannot simply just add lost coolant and top off the system…its not that easy to be honest as air pockets form in the system that need to be purged or nothing will function properly including the dash gauge that is trying to tell you the engine temp… It cannot tell you the temp of the engine when the gauges temp sensor is sitting in a pocket of air.

I would immediately stop driving this vehicle until you can have a competent mechanic look at it… Damage may have already been done with all the driving whilst having a cooling system leak or problem… You do not keep driving with problems like these…get to a real mechanic asap.

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