I just bought my 2nd c6, its a 2005 base with 102k miles. I got the car checked out before purchase and it came with full records and everything seemed to check out with the car. After about a month the car started boiling over and bubbling out of the coolant reservior after an hour or so of driving and occasionally the car would tell me to check coolant but the level was fine. I didnt see a radiator flush in the records so I decided to do it myself. I drained the radiator and started adding distilled water and then closed everything up twice and ran the motor for a few minutes then let it cool and drain some more. The weird part is that the cooling system would never take more than 8 quarts of distilled water and then at the end when I put the dex cool back in it wouldnt take more than 6 quarts. Gm stated it should take 12. Anyone have any idea whats going on here? Crud in the system? Air bubles? The coolant level says full but im afraid to drive it at the moment in case this indicates a further problem. help!

 

sounds like I'd put a thermostat in at this point

 

so, if I am understanding you correctly, it was boiling over BEFORE you did the flush ? if that is the case you need to inspect that water pump and thermostat ... with a 102k miles on the engine, you may be due to swap it out. Also, it would be a good thing to inspect for crud.

The water pump is really easy to remove and reinstall ... pull the belt, drain cooling system, pull the hoses , remove the 10mm bolts .. all readily accessible....

when you refill I do suggest getting a vacuum tool to refill as it will prevent air pockets that happen a lot with corvettes.

 

Yes it was bubling coolant out of the surge tank over flow before I did the flush. It was sporadic but after it happened twice I decided to do the flush.

 

At 100k, would pull the water pump and double check it, and change the T stat out as well.

Normally when the water pumps start to go out, they will leak as the Bronze guide bushings for the center shaft gets worn out, but in some cases, the impeller on the shaft gets loose, and it not longer spins with the front pulley instead.

So with water pump checked or replaced, leave the T start out for the flush part, then install it when you remove the dirty distilled water to put the Dex-cool back in (50/50).


Also, before doing anything, start the car and let it idle with the A/C on, and make sure that the raditor fan is running (should come on when the A/C is on). If the fan is not running with the A/C on, then start checking the fan connectors to make sure that the PWM is getting power.

On the back/ middle'sh of the passanger side of the raditor, you will see a connector that you want to disconnect and check it contacts both side of the connectors for any melting problems once you have it disconnected.



The PWM is the silver box, and the connector off to the right hand side is clipped to the back of the raditor about half way up on the passanger side. Its this connector that you want to first check to make sure it not melted/fired, then next on the list would be the PWM connector, the the last thing to check with the motor off, reach in and spin the fan by hand to make sure its free wheeling without any resistance (it's motor bushings not on the way out, and causing binding on the motor as it trying to turn, which in turn will cause more needed power through the connectors to melt them).