Herm

any tricks to replacing the coolant overflow tank on the 1993 LS400 or is fairly straightforward?

Is it possible to repair leak around the threaded section where the coolant sensor mounts ? If so how ?

Thanks, Herm

Lvangundy

I replaced mine.

Job took about 15 minutes. There is like 1 bolt or screw (forgot) and a hose clamp.

Only tips I have are to drain a little before you take the reservoir out so it doens't spill everywhere.

Pagong

what did you replace it with?

and do you have any pics?

Herm

a pressure test indicated leak was around the coolant level sensor. I pressurized the cooling system and poured some water on the top of the sensor - saw bubbles. This type of leak has been reported in numerous posts. I could not tell if it was the sensor housing, sensor o-ring, threaded section of the tank, etc. - you just can't see in there while applying test pressure.

I tried wrapping about 15 or 20 turns of pipe thread teflon tape around the o-ring on the sensor and screwed it back in - the leak was gone!! I'll watch it for a while and post the results.

Anyone figure out where the leak actually is ? Any other methods of leak repair ? A new tank is over $120 so I hope the fix works.

tvd51

Mine is also leaking. I replaced the O-ring but didn't help. Later I found out that there was a tiny hole on the top of the tank. I cover it with tape but it didn't stop the leak. It looks a bit messy but doesn't seem to hurt anything.
tvd51

Herm

tvd51 - thanks for the reply, I do not think the tape will work because pressure builds up inside the tank and will push it off. Since you can see the hole perhaps you can figure out another way to seal it ? Whatever you do would have to withstand pressure from inside the tank. Where did you get the 0-ring, do you recall the size ?

tvd51

I got the O-ring from Lexus dealer, its diameter is about 1". The hole on the top of my coolant tank is not visible but I can see the bubbles coming out. I guess I can try to seal that hole by making the plastic melt at that spot. At the moment the tape can't hold it but I think the pressure loss is small and as the result, the boiling point of the coolant will drop a bit.
tvd51

91LS400vgb

I know this is an old thread, but I just wanted to share my fix for the leak from the coolant level sensor on the expansion tank of my 91 LS400. I know this is a common problem for many. In my case, replacing the O-Ring with a standard 1-inch (R19) O-Ring did the trick. I disconnected the electrical connector from the level sensor, then pulled up on the sensor's rubber cover, being careful not to pull hard on the wires. I then used a channel lock pliers to loosen and remove the coolant level sensor, being careful not to damage the plastic. I replaced the O-Ring and then re-installed everything. I've been driving for a couple of weeks and it no longer leaks.