Hills and temperature

rx4ur7 · 08-11-2009, 02:46 PM

"The gurgling occurs when the car is shut off....it sounds like water returning into the overflow tank slowly from the vaccuum."

Is this correct, the water is going into the overflow when shut down? If so that means you are overheating and heat soaking badly. That is not vacuum but pressure. You could try a higher pressure cap, but I really don't recommend that for normal street cars.
Don't know if you got the new cap yet and the results.

Everyone, one thing to check on your radiator caps, the bottom piece of rubber, if it is wider in diameter than the metal support it will not allow the engine to suck the coolant back into the motor as the coolant contracts as it cools causing. This is where the vacuum comes in. Pressure from the expanding heated coolant is what pushes the coolant into the overflow.
The radiator cap is a two way valve.

ZachFD · 08-13-2009, 11:57 AM

well, at night, the car is rock solid with its temps. I drove it last night, temps were 85F, I did some WOT runs and ran a steep mountain....temps stayed right at 185F with fans on...occassionally fluctuated up to 195F.

Its only in hot weather/a/c on, that the car creeps up in temps...the other day in 105F, I turned on the A/c and watched the needle creep to 220F before I shut it down.

The gurgling sound is like a sloshing noise coming from the turbo area....maybe its water returning to the system from the overfill.

As far as the filler neck, there are a few dust bubbles at idle, and tons when I rev the engine up...at 4.5k rpms, the water level drops down deep into the neck and when I release the throttle is comes back up to the top with tons of champagn bubbles. We performed this with the hydrocarbon tester on the neck and it never changed colors.

The only spot I know of that could potentially cause any problem would be the radiator plug is cross threaded in, but its a very mild cross thread and its fit flush against its rubber gasket.

The motor is a mazda reman with around 50k miles on it. I replaced the thermostat not to long ago and replaced the 13psi ast cap the other day. I had this temp creep problem last summer and the summer before. In the winter there is NO flucuation in temp.

08-13-2009, 11:57 AM	#2
ZachFD Rotary Fan in Training Join Date: Jul 2008 Posts: 40 Rep Power: 0	well, at night, the car is rock solid with its temps. I drove it last night, temps were 85F, I did some WOT runs and ran a steep mountain....temps stayed right at 185F with fans on...occassionally fluctuated up to 195F. Its only in hot weather/a/c on, that the car creeps up in temps...the other day in 105F, I turned on the A/c and watched the needle creep to 220F before I shut it down. The gurgling sound is like a sloshing noise coming from the turbo area....maybe its water returning to the system from the overfill. As far as the filler neck, there are a few dust bubbles at idle, and tons when I rev the engine up...at 4.5k rpms, the water level drops down deep into the neck and when I release the throttle is comes back up to the top with tons of champagn bubbles. We performed this with the hydrocarbon tester on the neck and it never changed colors. The only spot I know of that could potentially cause any problem would be the radiator plug is cross threaded in, but its a very mild cross thread and its fit flush against its rubber gasket. The motor is a mazda reman with around 50k miles on it. I replaced the thermostat not to long ago and replaced the 13psi ast cap the other day. I had this temp creep problem last summer and the summer before. In the winter there is NO flucuation in temp. Last edited by ZachFD; 08-13-2009 at 12:03 PM.

08-11-2009, 02:46 PM	#1
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	"The gurgling occurs when the car is shut off....it sounds like water returning into the overflow tank slowly from the vaccuum." Is this correct, the water is going into the overflow when shut down? If so that means you are overheating and heat soaking badly. That is not vacuum but pressure. You could try a higher pressure cap, but I really don't recommend that for normal street cars. Don't know if you got the new cap yet and the results. Everyone, one thing to check on your radiator caps, the bottom piece of rubber, if it is wider in diameter than the metal support it will not allow the engine to suck the coolant back into the motor as the coolant contracts as it cools causing. This is where the vacuum comes in. Pressure from the expanding heated coolant is what pushes the coolant into the overflow. The radiator cap is a two way valve.