coolant gurgle/overflow

This is the 3rd time recently that my 95' V6's coolant has overflowed from the resevoir. This has only happened on warmer days >90, and after driving around town for a while. There have been times that I have heard a gurgling coming form the radiator, also on warm days. On all occasions these symptoms have not been noticed until the engine was turned off, and when restarted it has stopped. Only changes that have been made was a flush last fall and with cool weather until now have not had any problems.
Could it be a bad cap not holding pressure, or bad flush job? Any help would be appreciated, can't afford truck to go down!:shakehead

p.s. The temp gauge has never risen above normal.

Make sure there are no air pockets.
May want to check the cooling system for exhaust gasses.

How do you go about checking the cooling system for exhaust gases, and what will this tell me if exhuast gases exists? Also this gurgling/overflow is very intermittent, today was in the 90's and had niether happen.
-Thanks for the information.

I have heard there are kits available at autoparts stores used for testing for exhaust gasses. Where I worked, we would just use the smog machine.

I will look into the kits at an automotive store. But what does it tell me if there are exhaust gases found? Especially with the gurgle/overflow being so random, it happened Friday for the first time in about a week.

If you have exhaust gasses in the cooling system, then you have a failing head gasket. Headgasket failure is usually associated with high coolant temperature. Since you are not overheating I would be more inclined to think you just have air in the system.
Turn the heater on get the engine up to operating temp and make sure the cooling system is full first. Make sure your overflow bottle is filled to the proper level. It maybe just an air pocket.

Thanks that's reassuring. I'll see what I can do to get rid of the air pocket.

What does the temp gauge look like when this happens? Your engine is probobly just running hot. You may wanna check your thermostat and your clutch fan. Also, does your truck ever leak coolant at all? A pressure test of the coolant system would be a good idea.

The temp. gauge goes up to mid-point a stops, never risen above normal. As far as the fan clutch goes, I had some broken blades and tried an electric fan that runs all the time. May switch it back out, with new blades, and see if problem continues. Recently began to "boil" again, overflowed out of backup res., I turned on all heat an ran for a while and topped off once cooled down. Was told turning on heat could help release any left over air pockets from flush. May just spinning my wheels, may need to reinstall original fan, not sure. Any input is welcome. Thanks.

Turning on the heat will just allow the coolant to pass through the heater core, which if there were air pockets from the flush, would probably move them through to the radiator where they could vent to the overflow. I doubt that you have air pockets left in the system after that long, they probably wouldve worked their way out by now. I would go to an auto store and rent a radiator cap pressure tester, and also check the mixture of your coolant.

And does this relate to the installation of your electric cooling fan at all?