I just bought 1998 LS 400 with 100,000 miles on it. The car is nice and very proud of it.
Only problem I have is when I am waiting at the signal or in a traffic with AC is on and the car is not moving, the temp gauge points almost close to the red zone indicating hot engine temp. I live in Las Vegas where outside of car is almost close to 115 F in last couples day, but it concerns me. However, once the car get moving, the temp guage drops around mid-range. Is this the water-pump problem or anything else? Please help me.

 

Have you checked your coolant fluild levels? Sounds like that may be the culprit.

 

Coolant level is fine. Thank you. Maybe I need to flush radiator system?

 

try adding some Water Wetter by Redline into the mix, it seems like its just hot where u live. make sure also that the fans are coming on.

 

Thank you PureDrifter. Redline seems good idea. How do I check for the fan see if it works right or not working right. Just turn A/C on and the fan should be On as well?

Thank you.

 

Two things, first make sure that the single electric fan in front of the condenser is in fact working when the a/c is on. If so then you most likely have a problem with the clutch fan. My clutch fan went out, and although the aftermarket ones will work, the OEM one is really the best. The car should not overheat at any temperature under normal driving conditions, the use of aftermarket additives might decrease the temperature however it's only masking your problem. Fix the root cause of the problem first then maybe consider an additive. Just my 2 cents.

 

check radiator fins and see if there is junk in them this could be the culprate if its dirty pressure wash with electric fans removed

 

Thank you all for your input. I think I will take my car to shop I trust and have them look at it.