Strange cooling problem on 99 Century 3.1L

[tonynaia]

Hi all,

I have a 1999 Buick Century Custom with the 3.1 and 161,000 miles on the odometer. My story starts yesterday, after my drive home from the gym. I take an interstate and some back roads to get to my house, up some hills, about a half hour. When I got home, I heard what sounded like an open faucet under the hood. Then the car "gurgled" and about a quart of antifreeze fell out. I popped the hood and discovered my radiator cap was nowhere to be found. I would imagine it was attached when I left the gym. The car did not overheat, nor did it make any strange noises.

Today, I acquired a replacement cap, added coolant, bled the air out of the system, and took it for a test drive. About 40 minutes on a 50MPH road with some good hills. The car ran fine, did not overheat, and the heat is working great.

When I got home, I popped the hood and put my hand on the cap. The cap was cold, like the car never started. All of the hoses were hot. I grab a rag and slowly remove the cap. There was no hissing sound, and the fluid did not boil over when the cap was removed. This makes me think that the system is not pressurizing.

I replaced the water pump about 10 months ago. The thermostat is original. The head gasket and intake manifold gaskets were replaced when the car had about 20k miles on it. Also, there is no coolant in the oil, and the oil level has not dropped.

Where do I begin to look for problems?

 

[HotZ28]

Have you replaced the radiator cap?

 

[tonynaia]

Yes. It was a necessity as the old one was no where to be found.

 

[MelsRegal]

The cap was cold but what about the radiator itself? Do you have a temperature gauge in the car and if so did you have normal readings? You are sure you were given the correct cap? What manufacturer and part number is the new cap?

 

[JMurphy]

161k miles? And original thermostat? New low brand name water pumps can easily fail in under a year. But I would first replace thermostat. Could be stuck in closed position. Cheap thing to replace and could be problem. Even if it's not the problem, it's cheap and should of been replaced by now. So my first bet is thermostat and second thought would be a failed aftermarket water pump.

 

[tonynaia]

MelsRegal, I purchased a Stant 10231. The cap was cold, the radiator was hot, along with the hoses.

Jmurphy, Yeah, I really should replace the thermostat. It just seems like a terrible job haha. I will make that a priority. I would think it would want to overheat if the thermostat was stuck closed. At least, that has been my experience with thermostats that were stuck closed in the past.

 

[JMurphy]

I've actually had a defective thermostat about 20 years ago. Similar problem. Block was hot maybe 30 degrees above normal. Radiator.. I wouldn't say cold.. warmed up like a babies bath. When I pulled the thermostat, the needle on end was actually out and crooked. The whole valve was crooked. Stuck partially open. I know that's extremely rare. But I have had other buddies have thermostat valves only open slightly.