hey guys
99 gs400
i live in Toronto and its cold as duck here now
-15 degrees celcius

neways when i go to work i usually warm it up for a bout ten mins which bring my temp gauge upto about 1/4 mark and then leaving my street will bring me to about 2/3rds. crusing to work at about 80kmh or about 45mph for about 20 mins i notice that my coolant temp needle is dropping to about an 1/8th on the gauge and my idle is a lil high maybe about 1100rpm at idle in neutral at the lights which is a lil hi cuz usually its about 750 or about 800 rpm when warmed up. pull into work and so a few more minutes of idling before work starts and the temp gauge rises to about 2/3 and approaching half way mark and rpm is stabilizing to around 800rpm.

my guess is the thermostat. slow cruise out of the neighborhood will raise engine to operating temps close to half way but on the drive to work the rad catches all the cold *** air and with the t-stat open will not let the engine reach min operating temps? resulting in poor heat output from the vents which is propotional to the coolant temp??
what you guys think

thanks
Patrick

 

Most likely it is your thermostat. I had fairly similar symptoms a month ago. Changed mine out and everything is back to normal. Warms up quickly and needle stays rock steady in the middle.

Takes about 20 mins to DIY.

 

Check coolant level, make sure thermostat is not stuck open and lastly bad ECT

 

Thermostat being stuck open is by far the most common culprit to this. I have changed the thermostat on at least 2-3 daily drivers in my time. It's generally an easy DIY fix - you do have to burp the coolant to some extent, or your temp will fluctuate all over the place and you'll think you blew a head gasket. I was doing a bad enough job that I finally just bought this to make my life easier:

http://www.amazon.com/Lisle-24610-Sp.../dp/B001A4EAV0

 

use original lexus thermostat these auto part one always fail

 

thanks guys for the replies
frig man i really have to say that this forum is really supportive. this 99 gs400 is my daily driver. my other car is a 94 nissan skyline gtr silver actually both the lex and the gtr are silver neways, i am also part of a skyline forum and the vibe and aura in that forum is nowhere near supportive and informative as this.

thanks again guys

oh btw i bought the lexus a month ago and all fluids are at proper levels ie the coolant is at the top of the rad neck pretty pinkish orangey stuff when the engine is cold in the morning

 

I gotta similar problem as well. When the heat is on, the needle drops slowly below the 1/2 mark. But never below that when its at operating temp. When I cut the heat off, then it climbs back up to the above 1/2 mark then holds steady. Coolant is not quite warming up to operating temps.

 

-15 in toronto? damn.... it's 2C here in Calgary today, we're having a great winter! lol

 

replace the thermostat