Whitmanpc1

Greetings all! I was reading through older posts trying to find out if anyone has had this problem:

My car is overheating in city traffic with ac on. The heat gauge was all the way up, so I turned off the ac and I put the heat on, but no heat came out! Then I hit the highway and the gauge went back to normal and heat started coming out. The car SEEMED find on the highway and I even was able to use the ac.

When I got off the highway, overheating again!

I'm bringing it to Lexus this week to get a radiator flush, but I'm hoping someone here might have some input before I go.

The timing belt and water pump were serviced last year, so that can be ruled out. Could it just be that I need new fluid? The stuff I've had in there has never been replaced, and this is a 93.

Please let me know if you need any more information, and thank you in advance for your help!

CmputerWiz

Well in my good 'ol Chevy days, if the car was overheating but no heat would come out, either:
water pump is bad
water pump is not spinning (belt maybe)
not enough antifreeze

I haven't taken apart my entire engine yet, so I don't know the cooling system....yet. I wish there was a Haynes/Chiltons for this car! I would say it sounds like the radiator fan, but the fact that you don't feel any heat at low speeds kind of rules that out.

Check the antifreeze level, that would be my starting point. With the car COLD and not started for at least 4 hours, open up the radiator and see if you can see fluid to the top. Check the coolant resevoir (sp?) and see if it's up the the mark.

Tolerances on this engine are very small....so driving with it overheating will kill it fast. Make sure you get this one fixed soon!

SR

Whitmanpc1

I just started up my car and let it idle for 10-15 min. It was overheating just sitting there in the driveway, no ac on.

I hope this helps someone with some possible clues.

As for the last post, thank you very much. I'll wait to see if Lexus suggests the water pump. It better not be that: I just had it changed 20k ago!!! Unless, of course, they said they did it and didn't...(not a Lex shop where it was done..)

VQT

Are you telling me that 20K miles ago Lexus dealer replaced your water pump and timing belt wthout replace the antifreeze:eek:
Did they showed you the old timing belt and water pump?

Keep us post on the problem

Whitmanpc1

Okay, I tried some of that stuff that goes into radiator and claims to fix leaks. Well....it did!

I'm going to have the antifreeze flushed out this week when I make an appointment. Then I'm going to put more of that stuff in as a precaution.

Does anyone else have experience with that radiator additive that seals the leaks? Does it last long-term?

Thanks all!

CmputerWiz

I was the king of Barrs Stop-Leak when I raced circle track. I had a Nova that I raced, and the radiator would get holes in it all the time from **** hitting it at 100mph on the track. Maybe I should have put a front grille and bumper on after it got ripped off that one time....nah

I haven't used it in my Lex. I'm guessing it would be ok, but being that it uses a diff type of antifreeze....who knows!

SR

VQT

I would take the radiator out and have a radiator shop cleaned and fix the leaks. It is better in the long run IMO.
After all it is a 9 year old car

VQT 93 SC400 White/tan 110K miles

tek619

I had an SC with similar symptoms, It turned out to be a faulty water pump. The weird thing is that the water pump was replaced a year before also. Make sure you get the coolant replaced this time.