Cut-Throat

I took a couple of Pics. A closeup and one farther back. In reasearching the thermostat, it seems like the original equipment rating was 180 degrees. Do you happen to know a good place on-line that I can check this out?

Thanks again for your help!

LEXSOOS

Regarding thermostat, you got it right. This is what you're looking for.

Any on-line resources unfortunetly can't help here but 180 degrees sounds about right, just get your thermostat and replace it a.s.a.p.

Cut-Throat

I'll try and get a Thermostat in the next few days. After I replace it, I'll wait for a few hot days and see if this actually fixes the problem. I'll report my results on this thread, so if someone else has the same problem they'll know if this worked or not.

LEXSOOS

After you replace thermostat, just let the engine run alone for 30-45min, within that time keep your eye on temp. If everything is ok, take it for spin and see for yourself....you should be fine

Cut-Throat

An update:

Well, I replaced the thermostat this morning. A pretty easy job all in all. Only $20 for the thermostat and the O-ring gasket looked new and the parts fit like a watch! - Not like my old 65 Mustang, where the paper gasket was attached with a bunch of goo and the engine parts did not fit that precisely. The job took me about 25 minutes.

Unfortuantely, it did not fix my problem. I took the car out for a drive and got it heated up real good and came back to my driveway and let it idle for about 5 minutes in the 90 degree heat. Sure enough, the temperature gauge started creeping up past normal after about 5 minutes. I shut it off and think that my next stop will be the dealer. I think I covered all the cheap and easy remedies that I know about.

I'll continue to update this thread, in case anyone else runs into a similar problem.

Anybody want to venture a guess to what my solution is? The winner will most certainly have the respect of this forum

GSteg

iTrader: (15)

The problem is insufficient cooling.

did i win?

Perhaps it's the waterpump
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1999 Lexus GS400
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LEXSOOS

Insufficient cooling for sure, but what's the source

Once again, overheating might be caused by:
1. Bad thermostat
2. Bad head gasket
3. Low coolant flow thru radiator
4. Foulty radiator temp. sensor
5. Not sufficient amount of coolant
6 Radiator fan running low rpm's
7. ?

I would sugest you to remove thermostat completly, and check if it is still overheating, if yes than take a trip to dealer, i guess

Thats all i can help you with, thru internet. Don't worry you'll fix this soon

Bentley1

Have you ever used any stop leak products in your radiator? Those can clog up your heater core and many other parts of your cooling system, and cause over heating.

Even if you have not used any stop leak products, try having your radiator flushed. Don't just drain it from the drain valve in the bottom of the radiator. Take it to a radiator shop that can actually flush it out, and install brand new RED Toyota/Lexus fluid. You'll most likely have to take a couple of bottles of your own fluid with you.

What about your oil situation? Do you have plenty of oil in the engine? When was it last changed? I'm just stabbing in the dark here to try to help you, but it seems like if you were running the car without enough oil, and/or it is dirty- that it could be contributing. Remember, this could be a combination of 2 or more problems, where one of the problems has been there for a while, but it wasn't bad enough to cause a problem- but now a second problem has come up and pushed it over the edge and caused it to overheat beyond an acceptable level. Try switching to full synthetic oil while you're at it, if you haven't already.

Good luck

Cut-Throat

I have had this car since it was new and have babied it and pampered it for almost 8 years. Never have used anything like stopleak. Have had the radiator flushed on schedule. Plenty of oil and changes on schedule also.

Appreciate your comments, but I am thinking I have an issue like a water pump or fan speed problem.

This is really my first problem with this car in about 8 years of ownership, so I don't feel too bad. That is why I buy Lexus - Less problems. Thanks for your suggestions. I'll let you know

chuckb

if it only heats up under 25mph then it probably does have to do with the fans. if not, must be the waterpump.
did you always use toyota red coolant when flushing?

Tammy

Agree to have a radiator repair shop test the flow through the radiator.

How many miles are on the vehicle?

When the coolant was replaced, was steam distilled water used with the 50/50 Mix?
If tap water was used, suspended minerals may clog the radiator.

Have the fan operations been checked?

salimshah

What is the condition of rubber hoses? Inlet and return.

Over time, with heat, they become too soft and the walls collapse ... giving you restricted flow.

Also inpect the radiator front ... paper/card-board or junk may be clogging the fins.


Salim

slickgt1

iTrader: (1)

Have you chanced the radiator caps yet? That should be the first thing to do on all cooling systems. Trust me, if that cap is messed up, it will suck in air into your cooling system as the antifreeze cools down, then cause air block when it heats up. Try that. I think you have air bubbles that are clogging your system.

Cut-Throat

Well, since the Radiator cap is cheap and easy, I just bought one. I ran the car with the heater at full blast and A/C off, bled the radiator until all the bubbles stopped and the water was boiling. I put the new cap on and turned on the A/C and let the car idle about 15 minutes. Unfortunately, this also did not fix my problem. And the car started overheating.

I took the car out for a drive and shut off the A/C and sure enough, the car cooled down rather fast. But, as soon as stopped in my driveway with the A/C on and it was idling, the temperature gauge started rising again.

salimshah

With AC on do both fans turn on?

Salim