ck90211

Just changed timing belt, tensioners and water pump on 95 LS w/150K miles. Made big difference on how smooth and quite it idles and runs now. Old belt was OK but cracks showing. My idle speed has gone from 750 rpm to now below 500 rpm. Mechanic also put in 1 gallon of that red stuff (Preston version of the Toyota anti-freeze) + distilled water (50:50 mix).

Now my question. When I am cruising (fast or slow) the coolant temp seems to be normal (1/3 high on the temp gauge). But when I stop the temp seems to creep up just north of 1/2. I know it does not affect my drivability but I am just wondering if this is a common thing or symptom of something not done right? Wrong fluid? Not enough? Idle speed too low (thus pump not running fast enough)? Water pump not done right?

Thanks for any insights.

PureDrifter

iTrader: (10)

did you replace your thermostat? also, check to make sure the throttle cable and the throttle assy. itself is tight. if need be, have your idle adjusted.

qewani1

Normally RPM at idle must be between 500 and 800 RPM
http://www.ehow.com/how_5559253_adjust-low-idle-lexus-ls.html

Do u have idling problem with AC on? If so then try to clean throttle body.
http://www.google.ae/search?hl=ar&q=throttle+body+cleaning&meta=&aq=f&oq=

Inspect for coolant level when having engine cold.
Maybe your radiator leaks, since i had the same problem.
My car' s radiator was leaking only when car was idling with AC switched on.
Try to do same and open hood and ispect for any leaks.

I had repalced radiator, problem solved.
Your mechanic may broke this plastic radiator while he was changing the timing belt.

curiosul

If the temperature goes down when you momentarily rev the engine (or maybe after 5-10 seconds of over 2000 rpm) then you might have some air bubbles trapped in your system and you need a purge

ck90211

Which system? Coolant/radiator?

curiosul

system = cooling system which includes the radiator and the heating element in the cabin

Garage7RP

iTrader: (1)

You could still have air in your cooling system. Try to bleed the cooling system.

ck90211

Drove around with AC off today, and seemed OK. Will try AC on when rain stops in SoCal. Rev is now more stabilize at 500 rpm. Maybe new belt/pump just needed to settle in, and get coolant flowing to all parts? Will report if problem persist. Thanks everyone.

GRAND_LS 4

iTrader: (2)

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Seems like there is air in the system. Turn on your heater to full blast and let the car sit as you bleed the system. Most cars have bleed vales so all the air can escape. Turning on the heater will ensure coolant flows through heater core.

You could also have a faulty thermostat.

Thermactor

iTrader: (1)

Prestone red = dex-cool
Get that **** out of there and flush it out thoroughly! Use the factory red antifreeze from Toyota.

ck90211

After 2-3 days I think I got some idea of my problem. When mechanic refilled coolant he couldn't get enough in (because thermostat was closed), and in test drive afterward it never got hot enough to open), so the coolant reservoir tank looked full. Once I started driving it and getting it hot (thermostat opened), coolant level got low (got sucked into engine), thus causing coolant temp to go up.

So I can take care of this by just topping the coolant off.

For those who just got a water pump replacement, don't forget to check coolant level in a day or 2.

Just read the coolant forum and amazed at the controversy between Toyota Red vs. EG and Dex-Cool formulas. I am in the camp that believes Toyota coolant is probably better, so will get a jug to replace the Prestone Red. Thanks.

ck90211

Changed to Toyota coolant, temp shot up but realized some hoses were off (sucked air into system). After bleeding everything is back to normal. Temp about 2/5 high. Looks like problem resolved.

GRAND_LS 4

iTrader: (2)

Temp gauge should be slightly a hair below the middle.

nthach

Get all the air out of the system, but the LS does bleed itself through the surge tank.

Also, if the idle is erratic, but no CEL I would check the wiring at the cam/crank sensors to be safe. It's easy to misroute the wiring for those when the timing covers come off.