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Temp. Gauge Rises But Doesnt Overheat.


Djlai
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Hello, I have a 1993 Lexus Es300. My problem is that when I drive on residential streets the Tempature gauge increases past the first marker and gets almost into the middle and when I drive on the highway it goes back down to normal tempature. I have replaced already the Waterpump, Thermostat, Radiator cap, and replaced the coolant in the car three times. I notice when I first start my car it warms up pretty quickly. I know that the fan runs off of the power steering and I noticed my power steering fluid was kinda of low so I added more into it but still the problem exist. Can any one else suggest anything to me that would guide me to fixing the problem? Thanks for you time and reading this long post.

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not sure if i am reading this right but normal temp on the gauge is half way, ( in the middle ) any lower and you are running cooler

it might be the temp sensor as it seems the only thing left

although a normal first thought is the thermostat

who changed the coolant

if the mixture is too much of the dex-cool ( orange stuff) it will be different

it might also be air in the system ( but doubt that )

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When I first got the lexus the temp gauge would only rise to the first mark for the first year that I had the car. Right now when I drive the car it warms up really fast going to the first mark and when I start driving it in residential areas making stops the mark goes towards the middle but doesnt quit reach it there and then goes down when I start driving again. When the car was normal the tempature gauge use to just stay in one spot. I also am noticing some antifreeze being pushed out the reserve tank.

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with it being forced out into the overflow tank then there is high pressure

either air in the cooling system

( which usually causes an overheating problem not cooling)

or thermostat

sending wrong info to the ecu and temp gauge

the system is made to drain and fill the tank normally ( small amount)

who did the coolant change?

the first mark is usually still when cold

normal operating temp is halfway for the es 2nd gen (92-96)

which is basically straight acrossnot facing down or up at all

running cooler is better than running hotter

you do have the orange coolant right?

not green

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You have 2 fans.

Check to see if your high speed fan comes on. Idle your car on your driveway after a drive. You will find that the low speed fan will come on and then if the temp does not go down the high speed fan should come on just between the 1/2 and 3/4 point.

I think if the high speed fan fails there should be an code that can be retrieved by a reader at the dealer.

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I believe in the 93 ES the fan is run off of the power steering pump. That is why the pump is brought into question.

The 93 also only has one fan. Two fans were brought into play until later and then they were both electric.

Before you go spending alot of money, first visually check the radiator and A/C condensor. Alot of times the fins get bent and/or lots of debris and dirt get in between the two. If is very easily cleaned out. Dirt and debris build up here will reduce the amount of air flow that is supposed to pass through. Redection in air flow with screw up you cooling system too.

skp has a very good point that is often overlooked. If the coolant temperature sensor is starting to fail, not reading the right temp and sending the wrong signal, all readings are off.

This is easily checked with the proper scan tool. It is also easily replaced.

good luck.

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you seem to have 2 problems one is coolant flow restictions

and the other is you never seem to reach operating temperature

need to isolate and trace both problems on the car

also you never said what colour is your coolant

do yourself a favour bleed the system for the hell of it

it is free and takes about 30 minutes and no tools

take off the rad cap startt the engine cold and wait keep a bottle of distilled water to refill the rad as it bellows if there is any air in the system

it might be a ps pump being stuck in full assist

do you hear a whining noise from the engine alot even when not turning the steering wheel

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Hello,

Im sorry for not mentioning the color of the coolant. I did use at one point the Orange coolant but when I drained the car again after acting up and replacing the thermostat the coolant was getting expensive to keep draining and putting in so I just use the Regular Green coolant now. I dont hear a whining noise all the time only when the steering wheel is turned. So would that eliminate the Ps pump? Also I will clean out the radiator tonight and make sure everything is free of debris. Thanks for the advice you guys have been giving me. You dont understand how frustrating this is and how it upsets me inside when I can't figure out the problem on a car. I dont claim to be a master mechanic or anything but I try my best. I have to hand it to you guys though for knowing what you are doing. You are saving me alot of money. Thanks and I will come back as soon as I get some money and changed those parts out and will let you know if that fixes the problem.

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OH OOOH! How did you switch from the orange to the green?

Did you do a complete flush with water and continue with water until all the orange was gone. Then completely empty the water and replace with a 50:50 green:water mixture. You would have had to completely drain the orange coolant from the engine block, too. Just draining the coolant from the radiator is not enough.

The orange coolant (long life) is not compatible with the regular green. If the orange was not COMPLETELY drained, there may have been residual left in the system. The residual orange mixes with the new green coolant and forms a precipatate (sludge) that will clog the small passage ways in the radiator. Clogged passage ways will result in poor coolant circulation and poor heat transfer (in both directions). Thus giving you the exact situation you describe: non-stable and inconsistent temperature readings.

steviej

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i don''t know of the sludge problem from the 2 mixing,it probably is true i just don't know but makes sense

the red stuff it dex-cool from texaco first used by gm in the late 80's

is a higher temp than green ethlyn-glycol ( i bet i didn't spell that right)

that is the biggest diffence

a green coolant can be replaced to orange no adverse affects

but the red coolant cannot go to green it will burst seals and gaskets

you may have total destroyed you engine to save a few dollars

how long has it been in there

and immediatly flush the whole system with water and refill with dex cool

the long life is orange and i am not sure if it is dex cool or just a longer life ethyl glycol in orange

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when we Drained the system we totally flushed it out with water making sure there was nothing left of the other coolant. I took the thermostat out when draining the system and just ran a water hose thru it until nothing but water came out. I am leaning towards your other recomendations that it has something to do with the fan because this problem existed before I did the coolant change. When I first noticed the problem coolant was spewing out of the reserve tank and I had it check for head gasket problem but the mechanic said it was fine. So I replaced the thermostat thinking it was a stuck thermostat and that didnt fix it. So I went ahead and changed the water pump and Radiator cap. After doing that the water quit spewing out of the reserve tank but the temp gauge still keeps fluctuating. My old radiator cap was bad so I guess that fixed the problem with the reserve tank spewing. I notice though when I first start the car my fan comes on at a really low speed and I can grab it with my hand and stop it. I dont know if thats normal. I will check today if my fan comes on fast when It gets hotter though. Also you guys mentioned the coolant sensor temp and I will get that checked out as well using an ohmmeter.

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I think you have pretty much narrowed it down by process of elimination. good work.

whats a fan go for on a 93, $$$$ wise?

I have an 02 sot he fans are electric and in no way connected to the power steering. I am curious as to how this works. I should go find one and look.

steviej

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it is normal at start for the fan to spin slow

and i have also stopped mine with my hand when just started

i am not sure if it is the temp sensor but as sj said you have narrowed most components down

only problem is you have messed up some of them

( the dex-cool causes o rings gaskets and hoses to swell or burst)

you want to test the fan turn the ac on it will make it run at full speed

the ohm meter is the best way to check a sensor but

it seems to fluctuate like it should

are you using a half and half mixture of coolant and water?

this may also be a problem as all coolant will cause a car to run cooler and would expalin why you seem to find the coolant so expensive to flush should only need 1 - 1 1/2 jugs to fill plus water for a whole system

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My 92 ES300 is overheating and spewing coolant out of the reserve tank!

At first it was a slow coolant leak. The dealer said it may be a headgasket leak, and recommended that they take apart the engine to find other sources of the problem for a minimum cost of $4100. Since thats nearly the cost of the car, I declined and I put in some StopLeak (the dry powder type) in the the radiator, and topped off the orange coolant. This seemed to slow down the leak a bit. I was able to drive around for a couple weeks fine.

Then a couple days ago, while driving I noticed the temp gauge going up to near the top and steam coming out of the hood. I parked and lifted the hood and noticed the the coolant in the reserve tank is boiling out. After it cools down to the point that it stops boiling. I put in some Prestone Liquid StopLeak and refilled the radiator with about one or two liters of orange cooling.

After filling up the radiator with the orange coolant. I can drive about 30 minutes on the mostly freeway before the temp sensor goes high and the coolant boils out of the reserve tank.

Do you think my waterpump is dead? Could it be that I clogged my radiator somehow with the StopLeak stuff? Also how do you tell if a radiator cap is bad? I don't see liquid coming out of the cap so I am assuming its fine. Thanks for any help!

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pressure test the system. you can rent the tool from any Autozone. If it doesn't hold, then you got a leak.

If it is the head gasket, you can also back pressure each cylinder (with the radiator cap off) to see if the head gaskets are a problem. Children don't do this test without proper supervison. :rolleyes:

If you think it is the radiator cap, just replace it. If the problem continues, it wasn't the cap, but it only cost a few bucks.

It may be the thermostat, but I would not expect the overheating if the thermostat is of the "fail open" type. I believe that is all toyota uses. If it failed in the closed position, you will overheat. If is failed in the open position, you will not attain normal operating temperatures but you can drive the car.

My guess is the water pump. grab the water pump belt pulley at 3 and 9:00. Try to move one side back and the other side front. If you can wiggle it or is clanks it is dead. (my guess is this is the problem.) That is a dealer changed item.

In any event, you need to have a mechanic look at the car.

Stop leaks and liquid coagulants only treat the symptoms, the underlying cause remains and is gonna bite you in the wallet/!Removed! if you don't get it looked at. If you continue to constantly overheat, sooner or later you are going to crack your block or warp you cylinder head.

steviej

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  • 1 year later...

I don't knoe if it matters anymore, but the temperature gauge sending unit goes bad in early es300's and will only rise to the first or second line. It is under ten bucks and needs just a 10mm wrench to fix. If you don't, when your gauge starts to read normal you are actually over heating and you might be in the middle of the desert and blow a head gasket like I did.

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it is normal at start for the fan to spin slow

My '94ES did this from the first day I drove it out of the showroom until the day I traded it in. I checked this on other '94's and they all did the same thing, so I would say it's normal. ;)

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