BWLS400

Hello all,
I have a 99' LS 400 that is overheating. I just noticed this 2 days ago when i was driving in the city. I heard some gurgling and noticed that the temp gauge was rising. I parked the car, waited for it to cool down, and finished my drive home. I have searched other threads, but i didn't see much on 98-00 models. I have replaced the thermostat, but it still overheats. I did notice that with the car at idle speed, i can take a broom(sweeper end) and stop the clutch fan. Should i be able to this? Also, i noticed that the one A/C fan comes on but it's a very slow speed even when the temp rises. Lastly, how do you bleed this particular system? Any help would be greatly appreciated!

-Brandon

billydpowe

iTrader: (1)

first I would pressure test it for a leak, if none, pull the right front tire up on the sidewalk, (makes the jug the high point) and fill the system up until it is full... (use 95-97 as a guide).. my front fan runs pretty fast and I dont want to stop the inner fan blades, so I cant help you there..

PureDrifter

iTrader: (10)

sounds like it's got an air bubble.....
you need to bleed the cooling system

randal

Brandon, I believe that there is a refill and bleeding guide posted on a sticker on the inner fender or underneath the hood. At least there was on my 98.

You do not mention if this overheating just suddenly occurred or has been going on for some time. It is also possible that the radiator fins are getting clogged with dirt...leaves, bugs, etc.

However, I would suspect a leak in the system if this overheating just suddenly began. You were right to suspect the T-stat although they often fail in the 'full open' position for safety.

You have more cajones than me to stick a broom in a spinning fan but yeah, you can probably stop it from spinning.

If I were you, I would make sure the system is filled(with Toyota Red, of course) and take it for a spin on the highway. If it does not overheat at highway speeds but overheats in city traffic then it is airflow thru the radiator. Could be fans going bad but lots of things to check.

UNCNOR

iTrader: (1)

I agree with PD as my 99LS had a gallon size bubble also.The nipple of the engine cooling temperature sensor was not in contact with the coolant and gave a false reading.

BWLS400

I refilled and let it get up to operating temp and there were no leaks. I will look over it again tomorrow.

I will refer to the bleeding guide in the engine compartment that Randal mentioned. I have not bled the particular model before. Thanks!

I will check these in the morning. The broom thing was a way to diagnose a failing clutch fan on a 99 740iL that I had, so i figured i'd try it. I went ahead and ordered a clutch for the fan, as it was only $40. i noticed that when i started the car, with the hood open, the clutch fan would generate a good bit of air sitting at 800rpm, but died down to almost no air flow in about one minute. Thanks for all your feedback, and I will report back tomorrow.

BWLS400

I ordered and installed the new fan and it's circulating a lot more air. This morning, while the car was cool, I removed the radiator cap and put coolant in through the fill whole on top of the throttle body. I, then, topped off the coolant in the reservoir. I turned the car on and let it run until operating temperature. There is no bleeding guide under the hood, so i left the fill whole screw off until it flowed without any bubbles. I, then, put the radiator cap back on. The car will still run hot but it takes it much longer to do so. I'm thinking there is still more air in the system, since i replaced the thermostat. see cliff notes of symptoms below:

1) no heat at idle, but there is when revved to 3000rpm in garage. it was not doing this before thermo and new clutch fan install. there was just no heat and it ran hot
2) overheats after about 15 minutes of driving
3) A/C works fine
4) fans seem to be operating correctly now, as the old clutch fan was shot
5) cleaned a/c condenser and radiator out. wasn't much there to begin with
6) temperature still creeps.

My plan tomorrow is to jack the car up on the passenger side and begin to bleed and burp the system. Any other suggestions would be appreciated. This car is used for everyday driving. Thanks all!

RugbyDad

You still have air in the system. No need to jack the car up.. Do this: https://www.clublexus.com/forums/ls400/748666-overheating-issue.html#post8616551

randal

The bleeding procedure is really quite simple. Get the engine up to operating temp and hold the RPM's between 2500-3000 for a few minutes with the heater on full heat (all windows down). It is important to keep the RPM's at that level to purge the air bubbles and it is important to have the heater at "Hot" during that period. After the engine cools down (overnight) just recheck the reservoir and, if low, add some more red. Should hold unless you have a leak somewhere. You may also want to replace your radiator cap to ensure that the proper pressure is held on the system. Low pressure can cause boil over and loss of coolant.

BWLS400

All,
After bleeding the system, the car is running just as it should. I replaced the thermostat, fan clutch, and bled the system just like everyone has mentioned. One thing i did find is it's better to replace the refill bolt while the car is running, after all air seems to have been removed from the system. This procedure took me about 30 minutes. Also, be sure to use a "Spill Funnel" or you'll spend extra $$ on wasted fluid while the systems 'burps'. Thank you all for your recommendations and assistance. There is no telling how much i would've spent at an Indy. Thanks!

-Brandon

Kram

I would check the fan temp control for proper voltage looks to me to be the fan is not working right and the fan clutch only is in real use at speeds from 25 to 60 mph and it is not needed above 60 because of the ram air affect .the fan will run fast at low speed when cold but is suppose to slow down when the engine gets to normal temp and then turns off to save gas at high speed and when the temp is normal if the temp becomes hot the fan clutch will kick in as far as the electric fans go one is for ac on and one is for normal temp control and I think the one for normal temp control is bad or not getting voltage to spin the fan to keep engine cool when it starts to heat up.