Our 1988 full size Chevy van (Beauville) with TBI & 357 cubic inch motor has 72,000 original miles - used mostly for 2-6 mile trips - has always been garaged; body in great shape; runs well but lately have had to add radiator fluid: 1 qt. every 100 miles - no leak, but clear fluid coming out of tailpipe which doesn’t look or taste like antifreeze - oil doesn’t foam or show signs of water.
Looking for ideas of what it might be, cost of fixing and what might happen if I just keep adding fluid and don’t do anything about it.
Clear fluid coming out of the tailpipe is water, which is normal. When you burn gasoline (hydrogen and carbon) with oxygen, the result is water and carbon dioxide. If the car is warmed up, the hot exhaust will keep the water as an invisible vapor until it leaves the car, but when the car is cold, the water vapor condenses in the exhaust pipe.
Yes, you have a leak. It may only leak when the engine is running and the system is pressurized. You can take it to a shop and have the system pressure tested, or they can add a tracer dye to the coolant and check it again after you’ve driven it for a few days. Could be a hose, thermostat, leak in the radiator, water pump, etc. Up to a few hundred dollars to fix. This should be fixed, because the leak will get bigger until it loses all the coolant and strands you somewhere, unless you don’t notice in which case you will be stranded with a wrecked engine.
1 qt/100 miles is so much that if it was leaking into the cylinders, you would probably see white or gray smoke coming from the tailpipe. But it would be a good idea to pull out all the sparkplugs and check to see if any of them are fouled. If you are leaking into a cylinder that is a sign of a bad head gasket (many hundreds of dollars) or a cracked block (thousands of dollars to fix), both of which would probably be terminal events on a 23-year old vehicle, unless you really really love it. You can also check for a bad head gasket or cracked head by taking the car to a shop and have them use their emissions tester to test for combustion by-products in the radiator. If you have a cracked head or block, start looking for a new vehicle, and keep topping it off in the meantime. You can’t wreck the engine more than it already is.
Using a car only for short trips is the worst thing you can do to an engine. It may not be in as great shape as you think.
Make sure you add premixed coolant or buy the concentrate and dilute it yourself 50/50 with water. Don’t add concentrated coolant.
I second the water pump. It can seep and the coolant evaporate before dripping off but it will leave a yellowish trail out the drip hole behind the pulley.
One more thing to check are your hoses for a pin hole leak spraying on a hot intake or exhaust part and evaporating as fast as it hits the hot part. I’ve seen this twice in the last year.