Auto losing coolant, no apparent leak on ground....

Crack head, or blown head gasket…

pull your spark plugs, and check if they have a green tint… if they do, that’s it.

Engine appears to run smoothly - had a car once with blown head gasket and it did NOT run.

Are you pointing at a smaller leak??

It may well <...run smoothly...> until the coolant level gets so low that it expresses itself as a high temperature warning up to, and including, steam coming out of the coolant circuit in undesirable ways from undesirable places.

There is good advice elsewhere in replies to this thread. Please let the forum know how the investigation turns out.

This is over time small leak, it was a recall on the engine in all models except the Cougar… said the dealer,… how is that? They looked into it and it was put on the list.

The biggest issue is not catching it…

Also check if there’s a recall.

I girl I used to date had a cougar, it had the same issue… so I googled it, and they had a recall on the 302 engine for that. But not for the cougar… it took one phone call, it it was covered.

I had a problem like that once, the radiator fan had quit working... it would heat up and overflow the overflow container or something, never could find the exact location of the discharge, and drip out coolant, but only when the engine was hot....the coolant is clear, no color and feels like a light oil, it appears like water from the AC condensate so it's hard to spot...

"buy a bottle of Bars Leak Carbon Fiber Head Gasket repair."

Does that work without having to remove the head?

Make sure you use the carbon fiber version. Regular Bars Leak is an old fix, but the carbon fiber works much, much better.

This stuff also doesn't clog up an old radiator or heater core. It's the same stuff that we in California used to kill motors on that Cars for Clunkers program - the dealer had to pour this stuff into the engine oil, which caused the motor to freeze up - CA didn't want these cars being put back on the road or the motors being re-used.

The carbon fiber is added to the solution to strengthen the glassy substance - the material becomes glassy when it's heated and when it leaks out of the cooling system.

This stuff has a limited life. I've heard of people getting a year to two years out of it.

That glassy substance is in fact glass. It's sodium silicate. Same stuff as muffler patch. I hardens up with some heat and CO2. It will kill an engine in the oil pan but save one in the cooling system.

This is what I love about this site. Very knowledgeable people here and I am confident that the info I'm getting is correct - much different than the internet or ... ummm ... social media or ... ummm ... the news media

The traditional remedy for agricultural ploughing engines that leaked was to tip a mixture of chopped straw, chopped oats and pig sh!t into it before topping it up again. Works every time!

Let’s give that ‘Head Seal’ a try before we do that….

I am sure with that mixture,it would be simple to sniff out the problem.

Well, to be sure… you should give it a lick test first…

Your home made remedy sounds great! I love hearing stories like yours - stuff that actually works and can be made on the spot!

Years ago, I took a trip to Peru. Magnificent place with the greatest people! I loved it!

Anyway, I found out how they make their houses - straw, mud and horse/cow dung! They make up a mixture and form blocks, which they dry in the sun. After the blocks are nice and solid, they make their home out of it. They leave doorways and windows open - most of them can't get the windows or doors, so the house has cloth covering the openings.

When you have a moment, go to Youtube and look up a guy called Project Farm. His older stuff is cool - he tests old stories, kinda like those two guys who blow up stuff on TV. On one of his videos, he tries to run a gas engine on bananas - he purees bananas and pours it in the crankcase. Of course drains the oil first, then pours the mix in. Very entertaining and over the years, he's become very proficient in testing things. In fact, he now tests things to see which product is the best - he buys the items himself and conducts the tests independent from the manufacturer. Recently, he tested knives - anywhere from the cheap made in China stuff to Milwaukee and then some esoteric specialty manufacturers. I thought the Milwaukee would be pretty good, but the specialty knives were much, much better.

I will second Bars Leak.

My girlfriend had a leak around the head gasket which was caused by an overheat when she let the coolant level get low.

Bars Leak kept her in business for over a year until she could afford to fix it, a $1,000.00 job.

I hope your girlfriend is better now and not overheating.

Thanks, I knew there were products like that, but just had not gotten auto parts store......

A lot of the auto store stuff doesn't work. This is one that does.

When I was a teenager, we would buy that VX4 (or something like that) at JC Whitney's - it was suppose to fix a bad battery. Well, you can guess how good it worked. When a battery has a bad cell, pouring magic fluid in won't help.

Yes, this is possible. The smell of a sweet smell will be apparent when you open the hood with a recently turned off motor or with the motor running.

If the OP thinks there's a chance it's a leak, he can do a dye test to find the leak. The kits aren't very expensive and if there's a leak, it'll show.

Lots of advice given. I had the same problem, but fortunately under warrantee. Many trips to the dealer. They tried everything including a dye in the coolant to see if he leak was internal and showed up in the oil, all to no avail. Finally they replaced the engine, but never got back to me with the exact problem. Bars Leaks has been around for decades and can extend the time needed until the cash is available for a proper repair or replacement.

It could be a leaky head gasket. If you get white exhaust, then it's for sure. I recommend tightening the head gasket bolts, or better yet, replacing the head gaskets. But look carefully below the water pump for leaks there.

GM 3800 V-6 engines (late 1980's through 1990's era engines, as I recall) had a known problem with the plastic intake manifold gasket that would fail at various levels which allowed coolant to leak from the coolant passages directly into the cylinder. Antifreeze would exit through the exhaust pipe - no visible leak on the engine or on the ground. Mild leaks could go on for some period of time, with overheating due to coolant loss, but the catastrophic failure of the gasket would flood the cylinder with coolant and in the worst cases, hydrolock the engine at road speed causing all sorts of serious mechanical damage. GM paid out on a class action lawsuit some years ago.

Aaaaah, GM 3.8 V-6. Buick 231 motor, not the Chevy 229.

We had a 1978 Buick Century with the split crank (even fire) 231. Motor blew (rod bearing went) at slightly over 50k miles. Being a loyal Buick (and GM) customer, they agreed to rebuild the motor. We paid for parts and GM paid the labor (or vice versa). Anyway, it was a nice thing they did for us.

To this day, I'm okay buying GM products. I think a lot has to do with my dad being a GM guy and how Buick took care of us with the bad motor.

All - thanks for all the suggestions...

I already bought the Bar's, but she beat me to it and bought a new (slightly used) car!!!

Very excited since this is her first car that was not aged and beat up - good for her!!!