This weekend I'm replacing the thermostat and will be doing a flush and fill on the cooling system. I was wondering if i had to remove the waterpump to access the coolant temp sensor. I have been running super rich and getting 16 mpg on a good day. So my questions are.

1. Do i need to remove the waterpump to access the coolant temp sensor?

2. Should i just test and replace the thermostat and see where that leaves me?

Any suggestions are welcome. This is for a GSL-SE.

 

Bueller, Bueller

Is this a silly question?

 

1. Do i need to remove the waterpump to access the coolant temp sensor?

No - the temp sensor is mounted to the back side of the WP right behind where the outlet is located. You'll be removing this outlet to get to the thermostat, so just take a 17mm box-end (IIRC), and twist it out once you have some coolant drained out. If you have the replacement water temp sensor, you should thread this back in with some RTV or Silicone on it to seal it up really well. This sensor tells the ECU when the engine temp is hot so that it prevents electronic enrichment of the mixture.

2. Should i just test and replace the thermostat and see where that leaves me?

I'd replace it. If it's been awhile since you replaced the Tstat, then a new Mazda Factory part has a very good chance of running correctly from day one. If you wanted to test your old one to see if it was failing to open or was stuck open, that might tell you some more of why your engine is running overly rich. If the thermostat is stuck open, the engine will never get up to operating temp, thereby allowing the ECU to run a rich mixture - plus, the engine is designed to run at a certain temp for best fuel economy.

Try these things and then reply back here if it doesn't improve MPG. Make sure that you reset your odometer at a complete fillup, then the next time you get gas, fill it up until the pump stops - write down the gallons pumped, divide this by what it reads on the odometer, and there's your MPG. HTH,

BTW, check your radiator hoses while you're in there - might as well.

 

i thought that the thing on back of the wp housing was for the choke return?
the temp sensor is on the side of the block by the oil pressure.?

 

SE's don't have a 'choke return'. This temp switch is used by the ECU to determine when the engine is up to temp and it can return to the baseline fuel map.

 

Thanks Longduck,

I did not get around to doing any work on the 7 this weekend. It looks like i should replace the radiator and hoses while i'm in there. The radiator is a big, green, wet mess currently. I was amazed that i had never noticed how easy the Coolant temp sensor was to find.

My gas needle does not work so the only way i know when to fill up is by filling up around 180 miles or so. Every tank has averaged about 16.

When i get all this coouling system stuff replace i will report my findings on gas mileage. Maybe i will take some pictures of the process.

 

OK so i have begun to stock up on parts for a little cooling system rebuild. I have a thermostat from Mazdatrxi and soon will be getting new upper and lower hose with clamps.

What i am wondering is if this is the correct temp sensor?

http://www.partsamerica.com/ProductD...pe=290&ptset=A

 

There is a coolant drain plug on the drive side of the engine. Bottom of the middle plate. 14mm.

But you should remove the radiator cap and inspect the radiator for mineral build up.

 

I plan on taking the radiator out and having it rodded and dipped. The inside is scaly brown and pretty much looks like crap.