Antifreeze Disappearing From Overflow

Looks like about a quart a month (need to monitor it closer) disappearing. NO external leaks visable.

Has anyone used any of the "stop leak" products with any success? I am leary of trying this for fear that these type of products might stop up the Heater Core and/or other areas inside the engine!

My question is: Has anyone used a specific product that worked? This is a 1995 Chevy lumina 3.1, 72K

If I can't find something to stop this leak. Will it get worse? Also there is no increased moisture from exhaust that I can withness.

Thanks to Everyone In Advance!

Looks like about a quart a month (need to monitor it closer) disappearing. NO external leaks visable.

Has anyone used any of the "stop leak" products with any success? I am leary of trying this for fear that these type of products might stop up the Heater Core and/or other areas inside the engine!

My question is: Has anyone used a specific product that worked? This is a 1995 Chevy lumina 3.1, 72K

If I can't find something to stop this leak. Will it get worse? Also there is no increased moisture from exhaust that I can withness.

Thanks to Everyone In Advance!

Question, does yours have the one heater hose routed around in front of engine, along frame rail of car as a metal pipe with short rubber hose at engine end and at firewall end? If so check the metal pipe between them along bottom edge of the frame, located in front of the engines bottom pulley, mine rusted thru a pin hole there and though bottle was always getting low, you could never see any coolant any place on car, apparently dripping off to the road. if thats the problem, replace metal pipe with new rubber all the way, just a suggestion...

The 3.1's have a known defect with the lower intake manifold gaskets that allows a small amount of coolant to be drawn into the motor and burned. At the rate you are loosing it, you'd notice nothing in the way of exhaust steam.

You might be able to see evidence of it on the affected cylinder's spark plug, but I doubt it. That's a very minor loss.

It could be worth adding stop leak. I personally use Alumiseal, in the little tube, finely ground silvery powder. It works well on very minor internal leaks like that.

Once you add a product to it, never add more, or you do run the risk of hogging up the system. A lot of people don't put the product in correctly, and that can be real bad too.

If you use it, do this.

Remove the RADIATOR cap (I've seen people put it in the overflow resevoir, really!) and start the car and let it run until full operating temp is reached. Observe the coolant flow, and when the thermostat opens and the coolant is circulating strongly, bring the revs up slightly. This will make the coolant drop in the radiator slightly, dump the stuff in all at once. Hold the throttle until all the powder is circulated, then put the cap on before dropping the throttle. Have someone help you if you aren't dextrous enough to do it all at once. Then drive, drive, drive. People put the stuff in, put the cap on, and shut it off. And the sealant turns into a big wad in the radiator. Driving at least 20 miles will ensure even distribution, and give it ample time to be drawn into the leaking area.

Check your oil, too. If its chocolate-milk or gravy-like, the coolant is leaking into the oil. Check around under the throttlebody, too, my 3.1 was leaking there. It'd puddle up around the distributor plug and boil away leaving a strong smell of coolant around that area.

Usually you won't notice an exhaust symptom unless you're loosing lots, like I was. I went through an overflow tank FULL (not just cold-hot levels) a day when I finally had enough cash to fix it.

I agree with Cad and Jeff, you have an intake gasket leak and should get if fixed as soon as possible. Antifreeze is a terrible lubricant, and if enough gets mixed in your oil, it will take the rod and main bearings out quickly. Make sure to note when taking the engine appart if the push rod guides are part of the intake gasket or if they are mounted in teh cylinder head. This will denote whether you have a roller lifter or flat tappet engine (GM used both in 95, running change) and is important to ensure you get the right gaskets for yoru engine. As I always suggest, while you have the intake off, replace the oil pump drive o-ring at the same time, as this will avoid a bad oil leak in the near future. It's located in the center of the engine block just below the throttle body, and is very easy to change while the throttle body is off. It's a known problem with these engines, so don't be lazy and skip it or you'll be pulling the T-body back off to change it soon anyway.