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Ls 400 Coolant System Issues


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I have a 1993 LS 400 and the problem I am having is some leaking coolant coming from the resevoir bottle, from the coolant level sensor that screws into the bottle. Now I sealed it up tight, but water still trickles out. What really concerns me, is that after driving any amount of time, when I go to take off the coolant cap, I never get any sort of pressure coming out. It just comes right off. Any suggestions?

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This is a very common problem in the mid-90's LS models. I don't believe you can seal this sensor on well enough to prevent a leak here.

There are several flaws in this coolant overflow reservoir. (1) The reservoir is too small to hold the amount of coolant that comes into the reservoir when the car gets hot, especially if you fill the coolant to the top line when the engine is cold. (2) The pressure cap holds to a higher pressure than does the seal around the coolant level sensor. This forces coolant out of the sensor opening before the pressure cap opens.

The solution: don't fill the reservoir too full. Fill it only to the lower line (or slightly below). This will allow more expansion room.

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