krbrabec

I will begin with saying that I am new to Lexus ownership and new to the whole forum thing, but I have searched for a long time throughout this forum and other forums to find someone matching my condition but I just can't find anything similar, so if you guys here are aware of something already posted about, feel free to link me to it - I don't want to waste your time re-explaining yourselves.

I bought my first car about 5 months ago, a 1997 LS400. It is a great car but apart from some suspension issues do to it being old, it has a somewhat small issue that drives me nuts but I can't find the cause of it. When I bought this car, after driving it for about 45 minutes away from home through typical highways, it started to overheat. So I got off and found that there was hardly anything in the reservoir. So I filled it up with some water until I could get home and switch cars and go buy some Toyota red. After filling it up and bleeding the system with the bleeder screw and reservoir cap, I snugged everything back down. All was well until I checked it again and discovered my reservoir nearly empty. I filled it up again and bled it of air and no problems. The level sometimes dips below the low mark and I just add a little water to the 50/50 mix currently in there. Have not had any problems until last night. Last night, I was driving home from my friend's house when my temperature gauge does what it always does: got hotter until it got just above the normal running temp and then goes back down to where it has always sat, but this time, it did not go back down, with the needle exactly halfway between cold and hot, which is hotter than it has ever run when running normally. Coolant tank was full. Less than a week efore I bought it, this car had nearly everything replaced - radiator, cap, hoses, water pump, thermostat, and heater core. I still cannot figure out why I am loosing coolant and why it is now running hotter than normal.

billydpowe

iTrader: (1)

well to state what you already know... you are loosing coolant, because you have a leak... we dont know where.. but you can look at the heater control valve, it could be seeping under pressure... have your "new" cap pressure tested... they make bad ones, sometimes. IF the heater core was leaking you should have some wet carpet inside you could feel even if it looked ok.. and pressure test your cooling system, jug and all and check the drain ****. if all else fails, replace your temp sender switch (or you might want to start there, it is so easy and low priced). then: let us know what the results are.... I'm sure you know how to get ALL the air out of the system so it will function correctly.... it has been posted MANY times...

djamps

How does the underside of the oil cap look? Pull the plugs and look for anything unusual as well. (helping to rule out headgasket issues)

krbrabec

In that sense, I have done that before trying to source out a coolant smell coming from the right side of my car - at best it looks a little rusty maybe but definitely not a coolant mixing issue. I check my oil all the time for that. I don't actually know how to get to the plugs on this car, so more info would be great, I'm also sure LexLs has something on it, so I'll take a look

billydpowe

iTrader: (1)

they are in here..

dicer

Did you run the heater when bleeding and adding coolant? Some times it takes a while to get all the voids filled and air out, so you keep thinking you got a leak. If it doesn't stabilize in a week then its leaking. You said coolant smell on right side? Could be like Billy says heater control valve.
Temp gauge up and down, is either air in system, funky acting thermostat (take it out and check it), the sensor or gauge/electricals.

krbrabec

That would make sense, actually, because just the other day I ran my heater for the first time the other day and with my car completely warm, I was still getting cold air for a short period of time and then I got hot air, I presume after the core filled with coolant. My heater control valve does seem to open and close quite frequently when I am not using the heater (it groans quite loudly when it opens and closes) but I have never seen any leaks from it.