This is a spin-off from a thread I started called Older Car With Low Mileage: What Parts To Change? started on 6/3/09.

Background info to provide context:

On 4/23/09 I bought a 1998 Bonneville SE with 37,341 miles on it. Engine is a NA 3800 Series II. Since then I've been doing various basic maintenance repairs on it (oil change, trans pan serviced with new filter and gasket, etc).

The car looked to have Dex-Cool in it so on 5/8/09 I had the engine block, radiator and heater core flushed by a radiator shop and a new thermostat put in.

I've been checking the coolant level in the overflow tank once a week since then and it'* been normal.

Yesterday (6/9/09) I had a local Olds/Pontiac dealership do the following to it:

1) New plugs and wires (NGK TR55s and Autolite Professional Series wires)

2) New fuel filter (Purolator)

3) New serpentine belt (Goodyear Gatorback)

4) Had the ball joints and tie rods greased

5) Had MAF sensor filaments and throttle body cleaned and new TB gasket put on.

I dropped the car off Monday evening, the work was done Tuesday, picked it up Tues evening. Drove the car around doing a few errands on Tues night and it ran fine, no problems.

This afternoon around 1PM (6/10/09) I checked the coolant level in the overflow tank like I've been doing. It was completely empty.

I called the dealership, explained about the tank being empty and asked what might've caused it.

The service manager said that to replace the TB gasket the mechanic had to "remove some coolant" (his words) and that the mechanic evidently didn't fill the tank up again.

I don't know much about cars so I didn't think to ask how much is "some" given that the tank was completely empty or ask any other follow-up questions.

He offered to fill up the tank for me if a brought the car over there but I declined as I had coolant at home and would take care of it. (This dealership uses Dex-Cool exclusively as well.)

Turns out I didn't have enough to fill the tank to the proper level so I put in what I had then went to Wal-Mart and bought another gallon of mixes-with-any coolant.

I filled the tank to the hot fill level in the Wal-Mart parking lot then drove home, which is no more than a 10 minute drive.

After getting home I checked the tank on a level surface and it was COMPLETELY empty again.

I filled it again and went for another roughly 10 minute drive around the block then stopped to check the overflow tank. Again it was completely empty.

I drove to the dealership and explained what was going on.

The service manager (same one from the phone call) suggested that an "air pocket" (his words) was causing the problem. He called over the mechanic who did the work yesterday and asked him to help me out.

The mechanic took off the radiator cap, filled the radiator with coolant that I had (the rad appeared empty or very low when looking through the filler hole), put the cap back on and filled up the overflow tank.

He said the car should be fine now and to check the coolant level in the radiator first thing tomorrow morning before starting the car to make sure it was normal.

I drove home (the dealership is also about 10 minutes from my house) and checked the overflow tank.

The coolant level had dropped quite a lot but the tank wasn't completely empty. I decided to let the car sit and cool for awhile...perhaps 30 minutes at least.

I then checked the coolant level in the overflow tank and radiator again.

The tank was completely empty but the rad was full. I put the rad cap back on and decided to go buy more coolant.

The car would't start. The engine was cranking somewhat weakly but wouldn't turn over.

I thought perhaps the rad cap wasn't on properly. So I got out, took the rad cap off and re-tightened it, making sure it was on snug and secure then got back in the car.

The engine seemed to crank more strongly this time but still the car wouldn't start. I decided to walk away for a little while..maybe 20 minutes or so.

I tried again and the car started but billowed white smoke from the tail pipe for a good 2-3 minutes or so.

I decided to go back to the dealership to explain my latest problems and see what they could do.

On the way there I stopped at a supermarket and bought another gallon of mixes-with-any coolant.

I got the dealership'* hours confused and it turns out they were closed for the day. I again filled up the overflow tank with the coolant that I'd just bought and drove home. I noticed while pulling out of the parking lot that the "check engine" light was now on which it hadn't been before.

After getting home I checked the tank again and of course it was empty. Let the car sit awhile and tried to start it.

As of now (8:23 PM EST) the car won't start and the engine light is still on. The engine sounds like it'* cranking normally but just won't turn over.

I certainly plan on going back tomorrow to have them take care of this (if I can get the car started).

In the meantime can anyone please offer input as to what might be going on? Prior to today the car ran with no problems whatsoever.

I just got a 1998 Lumina.. It started overheating and having low coolant problems literally a day after I bought it.

I'm thinking I might have blown a gasket somehow; GM'* gaskets in the 3100, and your 3800, are cheap. They used cheap gaskets in a lot of their engines, so a lot of them have the same problems. There are replacement gaskets available to fix the car with. And, to add to the fact that the gaskets suck, that DexCool that was in your system could have been old, and started corroding the gaskets and other parts of the engine. Apparently after it'* been used up way too much, the PH level changes and it becomes acidic? But anyway..

Here'* one way to check, even though it sounds like you already have some symptoms..

Missing Coolant
Check your oil, see if it'* milky or it has white spots in it, that'* coolant in the oil.
White smoke from exhaust, or engine bay

But yeah, I'd say take a look in your oil and see if there are any signs of coolant trying to mix in. That along with the smoke should be a sure sign of bad gaskets.

Also, there are little strips to test the coolant in your system to see if there'* exhaust in the coolant, which also can happen with a blown gasket.

Good luck, those gasket jobs are expensive. Not the parts, just the labor.

Also, if you can help it, DON'T run the car until you know there'* no coolant in the oil. It can cause engine bearing problems, which happened in my '96 SE, and I had low oil pressure problems ever since [but the car still ran fine]

Brando thanks for the reply.

I just checked the oil now (10:45 PM EST) through the dipstick and it'* brown and somewhat translucent. I don't see any milky white coloring or bubbles in it.

I also unscrewed the filler neck that atttaches to the gray plastic engine cover and looked at the oil in there. Again it looks brown with no milky bubbling or spots in it.

Also the engine started twice this time and I let it run for about a minute each time. Hope it starts tomorrow so I can get to the dealership.

You say the gaskets might be bad. Are you talking about the lower intake manifold gaskets?

I'm aware of the problem with Dex-Cool turning acidic and destroying the lower intake gaskets requiring new gaskets and a new upper intake manifold.

But could that really be the problem in this case? As I said above I've been watching the coolant level in the overflow tank every week for the last month since having the entire system flushed out and it'* been fine.

Taking the car to the dealership was only thing I've done to it in about the last 3 weeks and if it is the gaskets I'm really surprised that they failed this fast.

I still suspect the dealership did something improperly which is causing this leaking coolant problem.

There is a coolant passage in the throttle body. I'm not sure why he would need to drain much coolant. It'* about the highest point in the cooling system. Just add some more and keep watching it.

Danthurs thanks for the reply.

You say to add more coolant and keep watching it.

I need to emphasize that today (6/10/09) the overflow tank was filled four times between 2-6 PM and in each case with no more than 10 minutes of driving the tank emptied itself completely.

That'* the problem: I keep filling the overflow tank and literally within minutes it'* empty.

Where'* all that coolant going? Into the engine somewhere? The oil chamber? I haven't seen any on the ground under the car.

Remove the radiator cap and fill it directly. You can check the oil cap and dip stick for signs of coolant. Also look for any signs of a leak outside, on the ground, etc.

Danthurs what signs of coolant leakage should I look for on the dipstick and oil cap? The milky bubbles and spots that Brando mentioned? Are there any other signs to watch out for?

After filling the radiator should I fill the overflow tank too or just the rad? And when checking the coolant level as you reccomend should I only look in the rad and ignore the overflow tank for the time being?

Don't know much about cars so that'* why I'm asking these things...

I'm going to go out and fill the rad now (I checked it earlier this evening and the fluid level seemed very low looking through the filler neck). I think I'll put a piece of cardboard under the car as well to see if anything leaks out overnight.

If the fluid level is low again in the radiator tomorrow morning what would that signify?

OK, Fill the radiator to the top and put the cap back on. Then fill the overflow to the line.

Coolant in the oil will give you foam on the dipstick and on the underside of the filler cap.

Placing some clean cardboard under the car over night is a good idea. It will help you find any leaks. Let'* see what we get in the morning.

I just came in from outside. I filled the rad and the overflow tank. Cardboard under the car too.

I checked the oil earlier tonight like I said above and there'* no foaminess either on the dipstick or on the underside of the oil filler cap.

Now to wait...and pass the night clenching my teeth and swearing over this @#%^&* problem....

Update: Took the car back to the dealership today, a mechanic looked it over and determined that my upper intake manifold and lower intake gaskets are shot.

Just what I was hoping wasn't the case....

Along with the frequent loss of coolant through the overflow tank it turns out I did have oil in the coolant as well...which I wasn't sure of because I don't know too much about cars.

I also was getting a lot of white smoke coming out of the tail pipe when starting the car. Time to have it repaired.

Thanks again to everyone who offered advice.