mstrsltr

Checked coolant reservoir before trip into 100 degree desert country and found the level all the way down to where the reservoir tapers into the spout.

Alarmed at how low it was, I added coolant up to the “F” line. Started driving and checked it again after about 200 miles of Driving to find that it was right back down to where it was when I’d checked before the trip.

So I’m assuming I’ve got a leak. But why, if there were a leak, would the coolant return to the exact same spot in the bottom of the reservoir?

Would it not just leak out completely?

Ive kept an eye on it and it continues to do the same thing. I haven’t had any issues with overheating so I’ve been putting off taking it in to my mechanic. Just haven’t had the chance and since it’s running and not overheating I’m not in a rush.

im just curious as to where it may be leaking from and HOW it’s leaking so that it always returns back down to the same exact level?

any theories?

thanks!

chiph9

It's common to need a new radiator after 10+ years. Look along the sides where the aluminum fins clamp onto the plastic end-caps for signs of red "crystals" or other leakage.

Denso makes a good replacement.

Chip H.

mstrsltr

chiph9

I've not done it myself, but everything I've seen/read indicates it's not super hard. The #1 thing to watch is that it contains a transmission cooler and you'll need to save all the transmission fluid, as the transmission is very sensitive to it's fill level.

This video has pretty good coverage of the process. Hopefully you don't have rust issues like he did.

muyoso

Mine did the exact same thing when I had my timing belt and radiator replaced. Had to fill up the reservoir like 5 times because it kept going down to the bottom near the neck of the reservoir. Eventually it stopped as I assume all the air was purged from the system.

chiph9

Yep. Ask the service guy for about half a jug of the coolant to top the reservoir off over the next couple of days.

Chip H.

dchan865

If you are due for a major work like timing belt, water pump job, that requires radiator removal, you could bring your own radiator to the dealer and have them replaced. Since they have to remove and install the radiator anyway, they will/may charge you a small labor fee and install it. That's what my lexus dealer did when I had my radiator replacement last year(I also supplied them the hoses, thermostat as well). I forgot how much they charged but it was a small reasonable fee. I got my Denso from Amazon for about $151, far less expensive than from the dealer. I think they were selling the part for about 700 if my memory is correct. Just talk to the service advisor and see what you can negotiate. Good luck.

ft0175

I’m new to this site so forgive me if I posted this in the wrong area or something, anyway my 90 Lexus ls400 today had started steaming from the corner side of the driver side by the headlights(also very little). I noticed the coolant reservoir started bubbling intensely and then coolant was all over the floor. Before this my coolant reservoir has always been at a half way mark and I didn’t really think anything of it as it’s never overheated or anything. I filled it up and then again it would be at the half way mark it’s never leaked on the floor I’ve never seen puddles till today when it steamed. No smoke is coming out of the exhaust and the oil has no milky color to it. Today after it leaked all over and steamed I filled it up and drove home as I was at the store when this happened. I made it home no leaks no smoke and no overheating but to an empty reservoir. I’m not sure what to do as I didn’t see any torn or cracked hoses under the car. What can I do? I can’t even tell where the coolant even leaked out from.Only had the car for a year and the owners before me were pretty good with it maintenance wise.
Thanks in advance for any help.

mrblister

I cant answer your question but perhaps post it in the correct forum you will get better results

chiph9

Agree - this is the wrong forum for an LS.

But... if it's steaming, that is because either A) you have plain water in there B) Your radiator cap has gone bad C) You really are overheating and the temperature gauge is lying to you.

Chip H.