Hi, I have a '97 Jetta VR6 engine swapped into a '95 GTi.
I have a performance chip and pulleys.
The heater core has been replaced recently after it had blown up.

Just recently, the coolant light has been coming on and blinking after about 1/2 hour of driving. (goes away when car cools a little)

The temperature gauge does not change from normal driving temperature, even when I drive it a little hard with the coolant light blinking. (I guess air cooling is good enough)

The coolant hoses seem to be a little hotter than normal (hard to remember how hot they used to be). The reservior is highly pressurized when I stop to check it after the coolant light has been blinking. When I get the reservoir cap off when its hot, the valve on the side of the reservoir shoots coolant out.

The car does not seem to have any less power than it normally does.

I put my ear close to the area where the pumps are (engine running) and there does seem to be some wirring sounds where the pump(s) are, but again, I'm not sure how normal this is since I don't normally have to cram my head in the engine bay while its running.

Anyone have some suggestions as to steps I can take to remedy the problem?

So far I've been thinking of getting the system flushed and if that doesn't work I was thinking of taking it to my mechanic to test the temperature sensor, then pump(s).

Any help would be greatly appreciated.

Things like that are best left to a mechanic, cause sometimes if youre not sure whats going on and try to fix it youreselfe you screw it up more.
It sounds a bit tricky.

Things like that are best left to a mechanic, cause sometimes if youre not sure whats going on and try to fix it youreselfe you screw it up more.
It sounds a bit tricky.

Probably you should try the guys on the Vortex, i don't know much about those VR6, i'ma mk2 guy. AF is good for Chevys and Fords but Vw help lacks. No offense to nobody. www.vwvortex.com ---> forums.

Sounds like a stuck thermostat (common problem on vr6) Its in the housing with all the coolant sensors.