'96 Saturn SL2 Leaks Coolant from reservoir Cap, Why?

See comment on radiator cap below.

I've often seen radiator caps that go bad over time. The symptom would be what you have described: loss of coolant. If the cap no longer holds the full 15 pounds per its original design, then the coolant will fill the recovery tank sooner and be pushed out the overflow while the vehicle is running (or when it has just been shut down since the engine is very hot and the coolant is no longer circulating.) Once the engine cools, the recovery tank fluid gets sucked back into the radiator resulting in the low fluid level when you check it when cool.

The simplest thing here is to replace the cap with a new one (they are fairly cheap and easy to replace) and then refill the radiator to the full cool line. With any luck this will solve your problem. If not, then you will need to look for the real source of the problem (plugged radiator or leaking heater core, failed cooling fan, bad coolant temperature sensor, defective fan relay, leaking/defective hoses or water pump) keeping in mind it could be a blown head gasket and you might be buring the coolant.

Good luck!

Bob

You could, but not likely given that you said the vehicle is not overheating. Try squeezing the top radiator hose when the engine is cool and see if you can see result in the overflow reservoir. This should verify there is no blockage.

Thanks for your suggestions.

It is only leaking at the reservoir cap (I can see it run out), the cap for the reservoir is a 15lb pressure cap.

The hose I speak of is not a radiator hose, this hose is more like an over flow hose about 1/2" O.D. and 5-6' long, but unlike an overflow hose it cycles back to the top of the engine from the reservoir tank.

Cheers, Jim

I agree with Bob. It's more than likely just a bad cap. They're dirt cheap at your local parts store. Just wait until the car has cooled down before you replace it. If that doesn't solve the problem, then you're generating excess pressure in the system or the system is overfilled.

While its being discussed, whens the last time you changed your coolant?

Cap went bad on my 97 earlier this year. It used to throw up in the driveway occasionally after shutting it down.

I remember some times like that, but it was me throwing up just before shutting down.

Ken

Assuming you're talking about too much beer, etc. Been there too. Contrastingly on vacation a couple weeks ago I had a single Mai Tai on the plane and got lit, then had heartburn and had to take a zantac. I've become a total lightweight.

I don't know where that old tag came from!

Same here. My consumption has gone so low as to be, for any practical purpose, zero.

Ken

I've become

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