1995 SL 1 antifreeze dissappearing
 

My low coolant light keeps coming on and I check the coolant level and its low. About 1 pint fills it up. Then a couple of weeks later, the same thing happens. No coolant on the floor of the garage. No leaks around any hoses. Don't see a thing. Dip stick doesn't show any signs of anything at least that I can tell. Where is it going? I'm afraid to drive it now!! Thanks
Jim

My LS1 has been slowly loosing coolant for a while. I have looked at it a couple times to no avail. This last weekend I put the car in the air and looked at it from the bottom. The coolant leak is where the heater hose connects to the heater at the firewall. There have been no drops on the ground since the leak is very slow. Sometimes the only thing you can find is a dry stain.

Drain the coolant reservoir. Keep the coolant.
Remove the reservoir from the vehicle.

Fill it all the way to the top.
Wait.
Wait some more.

The reservoir will sometimes develop a pinhole leak where it contacts the vehicle. Presumably from vibrations wearing through the plastic. It is high up on the reservoir so it will slowly leak until it gets to the level of the hole, then slow down the rate at which it leaks. You would think that the pressure when hot would be an issue with it continuing to leak in probably is somewhat but not as much an issue as when there is fluid above the height of the hole.

And as Andy said, sometimes all you will find is dried coolant on the underside of the vehicle because whatever it is leaking from gets blown backwards while driving and deposits on a spot on the under side of the car that may be nowhere near where the leak actually is. It's like an aerodynamic who dunnit

Also be advised the head gasket can weep and the engine will consume the coolant and you'll be never "find" the leak! Just went thru this with Whitey my daughters "new" 2000 SWII. About 1/4 of a tube of Alumaseal added to the CRT whilst "hot" and the problem went away. Use too much and you'll clog the heater core............:eek:

Looks like I dodged the bullet this time. The leak was from the drain plug on the radiator. I replaced the butterfly valve with a new one and the leak stopped

Nice!

Good news!