tccsmith

I own a 1990 LS 400 with 297000 miles on it (go, baby go!!). Recently, the temperature gauge started going to the 3/4 mark. I checked the coolant level and there was nothing. I added coolant, gauge went back to normal. Next day, gauge back up to 3/4. Checked coolant and there was none. There was none on the ground, none around the engine. Added more coolant -- this time it took almost 3/4 of a gallon! Car overheated 2 days later -- still don't see a drop of coolant. This may sound crazy but the gauge goes up and down depending if I'm on an incline. I'm hoping it's the thermostat. Any suggestions?

Tammy

Pressurizing out of the reservoir overflow? Any white or grey smoke when running?

insure the radiator cap seals aren't cracked or missing. Original rubber hoses?

Suspect a leaking head gasket or leaking cooling jacket. Have the cooling system leakdown pressure tested, engine cylinders compression tested, inspection of the plugs in each cylinder.

bigL

iTrader: (3)

You should check your oil.

Suneet

I had this same issue.. Its a very bad way to discover you're running out of coolant! I took the car to the dealer and they fixed the leak for $600 or so. I'll try and dig up my old papers to figure out where exactly the leak was.

tccsmith

Thanks. I was hoping not to have to take it back to Lexus but it appears that is going to be my best bet.

tccsmith

I'm curious as to why you say to check the oil. Does that have something to do with the coolant system?

PureDrifter

iTrader: (10)

its somewhat possible that u blew a headgasket and the coolant is mixing with your oil. if ur oil is a creamy "milkshake" like color then thats most likely what happened. Although i dont think ive ever seen a 1UZ blow a HG before

Suneet

Wow I just reread your post and saw how many miles you have. Congrats! I hope to push my 94 till that long too.

bigL

iTrader: (3)

Well said.Typically a GM problem.

DoubleWhoosh

Probably a leak with a hose somewhere most likely, or some cracked reservoir or radiator. Just gotta go hunt it down. Usually if it is a headgasket it won't run right either.