Overheating or bad gauge?

Excaliber · #1 (**permalink**) 08-14-2010, 09:15 PM

My radiator has a bleed valve at the top. BUT, the top of the radiator is lower than the top of the engine. Air can get trapped in the radiator and never move out to the higher part of the engine, so in my case I cannot bleed all the air out from anywhere on the engine.

My method: Park the car with the nose uphill at a good angle. Take off the radiator cap and start the motor. Monitor the engine temp by both the gauge and by sticking my finger in the surge tank. When it starts to get good and hot I know the t-stat has opened and I'm getting good flow from engine to radiator. Put the cap back on, open the bleed valve at the top of my radiator. I almost always see some bubbling as air escapes there. I fill my over flow tank about a third, go for a drive, the overflow tank fills up more with water being pushed out of the "over full" engine. As it cools down the overflow tank water is sucked back into the engine. After a couple of cycles I find the surge tank is now at the perfect level, about 2/3rd's full. The overflow tank is also at just about the right amount. Now I know how much to fill the overflow tank to as well as the surge tank on the motor when everything is cold.

Assuming you have an overflow tank and you find your having to add water to it pretty often (TO often) my guess is one of two things:
1. Water is evaporating from the tank (car sits a long time).
2. Water is being pushed out of the motor into the tank and the tank is overflowing. Eventually the motor sucks ALL the water out of the tank and back into the motor. At some point, it won't have enough water to suck back in and the system is now "low". You then add water to the surge tank as well as the overflow tank.

The question then becomes: Wheres the water going???

Voyager · #2 (**permalink**) 08-15-2010, 08:50 AM

I bled the temp gauge bung and went for a test drive. Steady 80-90 the entire time. You guys are magic. Next round is on me.

My punch list is down by one.

Thanks,
Bob

Voyager · #3 (**permalink**) 08-15-2010, 01:58 PM

I take it back. Went for a second ride today and the gauge went back to fluctuating back and forth for a while, and then it died. I’ll call the dealer tomorrow.

Blas · #4 (**permalink**) 08-15-2010, 03:47 PM

When you moved the brass tubing, you did so gently correct?
When you finished retightning the sensor end, and went for a ride, was the brass tube and its steel protective coil touching a spark plug wire or positioned so that a spark could jump to it from a wire on the cap?
That would kill it quickly...
You loose the gas inside the tube...a microscopic hole in the tube from the spark(s)
DId you get air air out of the connection?

Voyager · #5 (**permalink**) 08-22-2010, 01:11 PM

With 100 miles on the odometer, I sent the Superformance/Keith Craft engine car back to the dealer. The temp gauge now works, but the coolant temp fluctuation remains. Although not as frequently, the temp still spikes erratically to 110/120 in a matter of 2-3 seconds, then after a couple seconds, it comes back down just as quickly to around 90. Noticed it would drop sooner if I turn the heater on. Kept the fans on the entire time.

After a 15 min drive today, noticed the top of the radiator was extremely hot and the bottom was only luke warm. Air pockets or pump issue? Thoughts?

Sending it back to the dealer tomorrow…