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CELICA XX

Coolant Tank Leak (pics)

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Has anyone had this problem?

It completely trashed the driver's side of the engine bay...

I can't figure out exactly where it's leaking from, but the entire top of the tank is covered in fluid.

Do I just need a new plastic tank?

1993 LS400

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celica urs is leaking at the sensor...i found one on ebay when i first bought mine cuz the sensor was bad

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I suspect that most, if not all, early to mid-90's LS models leak coolant from this tank. The seal around the coolant level sensor is not adequate to handle the pressure that is generated within the tank when the hot coolant fills the tank capacity. The design people probably should have specified a pressure cap that would open at a lower PSI than the one that is on there, but that's hindsight. The expansion tank also should have been bigger.

Some folks on this forum have talked about trying to seal the level sensor better (epoxy, perhaps?). The danger in this, as I see it, is the possibility that the tank would rupture if the new seal is too good.

One thing that can be done to lessen the problem is to fill the tank (when cold) to a lower level than the lines call for. Make the level about an inch lower than the bottom line. This will give you more expansion room in the tank.

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I suspect that most, if not all, early to mid-90's LS models leak coolant from this tank. The seal around the coolant level sensor is not adequate to handle the pressure that is generated within the tank when the hot coolant fills the tank capacity. The design people probably should have specified a pressure cap that would open at a lower PSI than the one that is on there, but that's hindsight. The expansion tank also should have been bigger.

Some folks on this forum have talked about trying to seal the level sensor better (epoxy, perhaps?). The danger in this, as I see it, is the possibility that the tank would rupture if the new seal is too good.

One thing that can be done to lessen the problem is to fill the tank (when cold) to a lower level than the lines call for. Make the level about an inch lower than the bottom line. This will give you more expansion room in the tank.

My expansion tank has 3 hair line cracks about 1/2" long around the level sensor, I used epoxy to seal the cracks and reduced coolant level to about 1"-1.5" below the lower level. I didn't see any coolant leak for several months after the fixes.

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The sensor unscrews and when you remove it you'll find an O-ring around the top thread area. Be sure to get one the exact diameter and thickness of the ring. Or you will not be able to screw the sensor all of the way in. If you can wait just order one from Lexus.

This fixed my leak.

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The sensor unscrews and when you remove it you'll find an O-ring around the top thread area. Be sure to get one the exact diameter and thickness of the ring. Or you will not be able to screw the sensor all of the way in. If you can wait just order one from Lexus.

This fixed my leak.

oh wow... so you can purchase that o-ring by itself from the dealer ?

I thought for sure I would be stuck getting a whole new tank !!!

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dont put the oring in dry..put some sil glide or something on it

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When I noticed mine leaking, just reduced the level and it reduced the leakage about 90%. No cracks that I could see, so I left it. But now that you guys have sourced the o-ring for me, I'm going to put it back on my list. Thanks for the info. :cheers:

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I'm glad that worked for you.

Which plastic epoxy did you use? I'm sure many brands will work, but as I read through the forum looking for a solution, it's nice to know which product exactly was used so there's no question of what to get.

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mine has always done the same thing but not to that extent. Like CUMAN, I just leave the level slightly lower and have little problem. I found there is only a thin margin between low enough not to leak and tripping the low coolant light. I would probably use JB weld for soemthing like that. Did you happen to price the tank?

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the coolant tank was a bad design. the sc's and gs' do not have this sensor they have a completely closed tank which is what some owners purchase. i sealed mine with oil FIPG. works great. this sensor will leak eventually but basically it is not needed. if you seal it properly then you will not need to watch the level or anything because the amount of coolant in the system will remain consistent.

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Which plastic epoxy did you use?

I used DEVCON High Strength Plastic Welder (at Wal-Mart for $2.88).

After cleaning and drying the tank... I also used 100 grit sandpaper to roughen the surface around the sensor, before using the epoxy.

I let it dry for 24 hours before starting the car.

No more leaks.

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