2007 Miata overflowing but not overheating
Asked by GuruT3F5F Aug 20, 2018 at 05:38 PM about the 2007 Mazda MX-5 GT RWD
Question type: Maintenance & Repair
Bought a 2007 Mazda Miata for my daughter in the
spring. I noticed the overflow Reservoir boiling
over, but not overheating. I read all the online
threads that pointed to either the stat, the cab, or
the entire Reservoir. I change Reservoir cap, and
thermostat. Ultimately also changed the radiator.
Still overflowing through the Overflow hose but not
overheating. I understand the system is
pressurized, so not sure what is left to swap out in
order to get this thing to maintain coolant level.
7 Answers
It is entirely possible that the coolant sender for the gauge is inaccurate, anytime ive seen the coolant boiling out of the overflow its because the water pump is shot
Lots of compressed gases being pushed into the cooling system could make it look like it is boiling.
Thanks for your responses. 1. Regarding the water pump...I did a visual check when I had stuff out of the way during the radiator swap... didn't see any leakage, and it isn't noisy... bearing rattle. That may not be a very comprehensive test, but it didn't come up with the service guy who checked it out either. 2. Regarding head gasket... I don't see any mix of coolant and oil in either place (dipstick or reservoir). I will keep an eye on both of these potentials, but there is no evidence...yet. Could it be an obstruction somewhere other than the radiator?
It could be, passages can become clogged over time but it's not very common in newer vehicles. You'd have to remove the water pump and inspect the fins for wear or corrosion, I've seen one so far gone there really weren't any fins left they had completely deteriorated!