cgroom

The temperature gauge continues to go above the have way mark. Yesterday it was 88 here and I ran the a.c.. The gauge got a little over the second white mark from the top. I don't know if this is normal, I have taken it to a mechanic twice and he said I had nothing to worry about. I am just used to the gauge staying right in the middle, and this one does not do that. The fan that cools the engine is almost always on as well. This is another thing that leads me to think there is a problem.

Would you mind telling me if your 430 gauge moves around like mine? I have to get something done before I hurt the engine, that is, if there is an issue.

Thank you very much for any help/advice you can offer. I really appreciate it.

kjcole

Temperature regulation in this engine is pretty rock solid - that gauge shouldn't be moving around once operating temp is reached. So are you saying that the temperature is moving around a lot, or that this particular car's gauge reads higher than a previous 430 you've owned? In any case I'd make sure that your coolant level isn't low (air in hoses), and then think about the next easiest thing - change the thermostat. If the fans are running constantly then I agree that the engine is running a little hot. Also, check the condition of the coolant - any evidence of oil or anything that doesn't look like pure anti-freeze? Another possibility is a partial blockage somewhere (radiator or water pump). My radiator cap (the metal one) disintegrated (rivet broke) and I had to fish the pieces out of the radiator.

If you think that the car is indeed running hot, and the mechanic says it is just the gauge, then he should have an infrared heat sensor (most do) that reads the infrared levels from various parts while the engine is running up to temp (convenient when trying to determine if an air-cooled engine is running hot). I think Lexus probably provides specs for the temp at the top or bottom of the radiator.

cgroom

thank you so much for the info. i am going again and telling them what you have said. if anyone else has any other thoughts, please send them my way...thanks again

Habious

My 03 start cold, comes up to temp (needle dead-center) and never moves.

I'd consider anything other than that a problem.

Personally, I'd take the car to your mechanic and ask him to replace the thermostat, just for your piece of mind.

jzwu

Take your car to a different mechanic.

My car's temp gauge needle stays in the middle and never moves even I use A/C running at 80 mph on highway in 90F days.

momssc

fan runs constantly with ac on, that is normal

416tt

iTrader: (1)

mine actually always stays slightly above the middle line... my thermostat was changed with timing belt last year... I dont notice any over heating or anything

scyul

Hi, I had this problem with another car. Your rad and/or condenser is probably very dirty… Here’s how I fixed it:
I fabricated an adaptor for the garden hose using 1/2 inch copper pipe (plumbing pipe).
I took a piece of copper pipe about 24 in long that I flattened all along to be able to fit it between the rad and condenser. Leave one end round to attach it to the garden hose. I folded the other end to seal it and make a cut thru the wall with a metal saw (one flat side of the pipe) at about 1 inch from the fold.
Then, remove the two brackets holding the top of the rad so it can be moved back slightly. Use the special hose adaptor you have just fabricated the hose all the crap out of the rad and then from the condenser by inserting it between the rad and condenser… You’ll be amazed to see what comes out of there.

Good luck!

sorka

Same with mine even in stop and go 105 degree weather. There is no normal case where the needle should ever move after the car is up to normal temperature. The cooling system has huge headroom in it to regulate the temperature precisely and it moves above the middle, then you ate that headroom up long before you actually saw the problem.

The things to check in order of increasing seriousness.

• Low coolant
• Thermostat
• Water pump
• Deposits in radiator
• Blown head gasket

mdpuff

I agree that you should first check your coolant level, in the rad not just the overflow tank. As previously posted the next thing I would check is that the front of the rad isn't plugged, seen it many times when customers brought their vehicles into our shop for over heating where grass, tree fuzz and you name it somehow gets sucked in between the A/C condenser and radiator plugging it off causing over heating and these cars do not take kindly to over heating. Take your air filter intake out, unbolt the 2 top rad mounts and tip back your rad back to see in between, you might be surprised as to what you find! If it's plugged up use what ever means it takes to wash it out, the afore mentioned spray tool sounds like it would work like a hot dam! If that isn't the problem then I would look at replacing the T-stat. Thermostat problems are rare on Lexus but can fail.

Good luck!

cgroom

Thank you to everyone. It was the thermostat. Replaced that, flushed and replaced coolant. It is perfect now. Now I have piece of mind. You all were very helpful. Thank you again.

416tt

iTrader: (1)

Glad to hear that its out of the way !!... i realized the second white line isnt in the dead center. so the mid point is actually slightly above the line.. so I guess im good too

mdpuff

Good to hear you got things sorted out, last thing you want is to over heat and damage your engine. Glad it was something simple and not an expensive fix.

Harold57

Glad that you got it fixed cgroom and welcome to the forum.

I think that I'd start looking for a new mechanic. A bad thermostat is just about as basic of a diagnosis as they come. There's not much of an excuse for his missing that.

SC43052

Just replaced my radiator this weekend due to a leak. I also was surprised at the crap that was trapped on the front side of the radiator.

Excellent advise by those who say loosen the top brackets and just tip the radiator towards the engine to allow vacuuming the front side.

Agree with others - don't use that mechanic again. The 4.3L engine is rock solid on the temperature gauge once it reaches operating temperature. Any deviation is cause for concern.

And if you see it climb towards the red stop the car immediately. All aluminum engines have very little tolerance for overheating.