ddutti

The coolant level on my 2002 RX300 (95k) was low, so I filled it up Saturday morning when cold. My wife used the car Saturday. When I checked Sun morning, it was once again very low. No leaks on the newspapers below. Filled it up again. Car was not used all day. This morning, level still full. Obviously, its leaking while running. Any suggestions on how to troubleshoot?
Appreciate any help!

bob2200

The first things to check are: (1) the engine oil to see if the coolant is going into the oil and (2) the exhaust for white smoke to see if it is being burned. After that, there is a device you can get to hand-pump the cooling system up to operating pressure and then see where the leak is. I don't know if these readily fit a Lexus. Maybe I'd try to check the water pump for signs of free-play in the bearings.

Note: these are general steps. I don't have any experience with this issue on a Lexus.

lexus114

you might want to pop the radiator cap,(when cool of course) and make sure it`s full in their.Clean the cap under a faucet before putting it back on and clean the neck of the rad. where the cap will seal,makes for a better seal that way. As far as using fluid,my 2001 does this some times,(especially if i`m running it hard) and I have no idea where its going.your water pump may be to blame,heater hose,even if a really small leak,this can happen.Or,a head gasket going bad. btw,are you adding the toyota red coolant?

ddutti

No. The Toyota red was in the reservoir, but as it was the weekend, bought Prestone 50/50 and added.

bob2200

Bad idea, in my opinion.

code58

I second that opinion. Toyota red is expensive but you get what you pay for. That is the finest coolant I have seen in all my years working in automotive. I liked it so well I even changed my wife's '02 Camry from the pink extra long life to the red long life. You don't want that Prestone in a Toyota product. (yes it is a Toyota product)

code58

You can get an adapter to fit the smaller Toyota radiator neck. Warm it up 1st and then use the pressure tester. It WILL almost for sure tell you where it is leaking (unless it is a head gasket leaking internally) My bet is it is a head gasket. Toyota had problems in the 90's with the head gaskets leaking on the 3.0 Liter engines. The block and head are both aluminum so you have a lot of expansion and contraction- harder to keep the HG from leaking than on a cast iron engine. Good Luck! I hope for your sake it is something easier than that.

ddutti

To update on my original post from last week......Lexus of Memphis took a look at the 2002 RX300 early this week. They could not find a leak in the coolant system nor did they see any anti-freeze in the oil. Went ahead with the 90k major service. As luck would have it, received a 20% off coupon for major service from Lexus this week. Very timely!
Still can't figure out how the reservoir could almost completely drain after just one day of use after fill up, but if the dealership said it was ok, then this novice won't argue. I will look at the reservoir every few days for awhile just to make sure.
Appreciate everyone's comments and thoughts from last week!

David

lexus114

mine does the same thing sometimes,go figure? just another rx mystery i guess.

ddutti

Lexus114:
So what do you do? Just live with it and check coolant every few days? Have you been doing this for a long time?
I looked this morning and it was down 2" from the full level. This is after Lexus took a look and found nothing suspect last week just before the 90k major service.

salimshah

The heater core may be missing the fluid. As you run the heater, when season changes, the coolant level may drop.

Salim

code58

The coolant isn't just vanishing into thin air. It is either leaking it or burning it from a leak into the combustion chamber. It may very well not show up in the oil, depending on where it is leaking. If it shows no external leak, pull the spark plugs and inspect them. If it leaking into the cylinder and not into the oil, but rather burning it, it should show some evidence of it on the spark plugs. I still say do a leak test both cold and hot, as much pressure as the the pressure tester will pump up (it will only pump so much pressure), it shouldn't pump more than 18-24 lbs. as long as it isn't one of the newer higher pressure type. Keep the max pressure on it as it warms up- the leak should show up one way or the other.

lexus114

I agree with code58. try that and see what you come up with. mine doesnt seem to use as much as yours does.