thats just a start...I now get about 90 or so miles on 5.500 gallons,was getting 60 if that, brand new water thermo sensor airfilter 195 thermostat took the 180 out,, Runs alot better(there is a god)... what should i replace Next?

 

why would you change the thermostat to something warmer and aftermarket???

Do you want to smoke your engine... is this some sort of engine death test???

 

last summer i took the 195 out and put the 180 in..Big Mistake. mileage suffered.. so i put the 195 back in and replace a few things.. Boosted my milaage back up agian

 

hey put a 165 in:-P .. bad move.. put colder in not hotter... unless you hate your car and are trying to get a jpec engine in there. water boils at 210 or is it 215 what the hey its close enough.. small margin on the over heating sector...... change one variable at a time ...themostat ... thermo sensor(you cant say which one was the cure).

 

I've noticed my gas mileage suffering in the cold, and my engine does not heat up (S4 N/A) I waist just under a half tank cruising around town.
Whats the part # of the winter thermostat I should be using, and how much does it cost?

but if I'm going slow my engine heats up to about half way, then when I start cruising it goes back down almost to the C.. I'm sure my clutch fan is dead and I really should put my shroud back in! (was too lazy to put it back in when I changed my waterpump)

 

dunno.. i beleive that 195 is what the car should have. was tired of seeing the temp on the Cold all the time...Now its Under half way... .

 

My thermostat opens up at ~170 I'm pretty sure. I can sit and watch my autometer gauge after first turning on the car (cold) as the temp slowly rises and gets to about 170 when it opens and the cold coolant from the radiator flows in and the temp drops again.

195 is too high, so what if your gas mileage suffers a little? Would you rather your car be hotter, possibly overheat? At the very least the hotter one will just shorten the life of the engine, and if it's already got a lot of miles would you rather save a few bucks on each tank of gas, or wear the engine out and have to replace/rebuild it?

180º is stock right? I would think you wouldn't want to go ABOVE that at all.

 

What's "in the cold" mean exactly? Where on the temp gauge?

 

All i know is when i got the car it came with a 195... last summer it got HOT and the temp got alittle high. So i put a 180 in. Cant find a 170 anywhere Do they even make them? anyways with the 180 in the winter anyways the temp gauge needle was hardly moving off the Cold mark. I know the damn thing works and it should run alittle warmer than that. its not going above half way so its not to Hot,, thats kinda what i go by..

 

I said the temp gauge reads ~170 when it opens, I have no idea what thermostat is in there. Someone earlier said put in a 165, maybe it's that? Not sure.

All I know is that in the winter my stock gauge sits around 1/4 with e-fan that hardly ever comes on.

Normal for an s4 temp gauge is around 1/4, half is getting warm but is okay. On my car 1/4 on the stock gauge is ~180 measured at the block and 1/2 is ~200+ at the block.

 

The correct thermostat for the FC opens at 180degF, and should only be bought from Mazda. IMO using anything else is pretty foolish. Why you would want your engine to run hotter than normal is beyond me.

99% of the improvement would've come from replacing the faulty thermosensor. You'll probably be losing a bit of power from the higher engine temps. If you put a "high-flow" filter in the stock airbox you'll gain nothing. If you installed an exposed pod filter you lose most of the gains from reduced restriction due to the hotter intake temps.

 

I'm pretty sure the water thermosensor is what increased your mileage as NZ said. Sorry but the stock temp gauge sucks. I admit the s4 design is much better than the s5 design but running a tstat that opens at a higher temperature is damn dangerous for the engine. If anything I would say the 180* tstat you were using before was defective (stuck open possibly). You never did say it was mazda OEM.

 

guys, i can buy a 160 thermostat for my car, i want to replace mine, is this one too kold?, should i get one a little higher...?

 

Why not just get an mazda OEM one? I'm pretty sure it's under $20 and is proven to work.

 

where did you get the Water Thermosensor?

 

that's at regular atmospheric pressure. You're cooling system is at higher pressure, and mixed with antifreeze, so the boiling point is much higher then just regular water at regular pressure.

 

The Mazda OEM thermostat is the best way to go. Mazda engineered the FC to run best around the temperatures the stock thermostat allows.

 

The theory behind running an engine at a higher operating temperature is that generally fuel maps are leaner when op temp is warmer, just like when the engine is cold it runs rich due to the temperature. You see a lot of newer vehicles running 195-205 consistently by manufacturers efforts to push teh limits for fuel economy. IT is more stressful to the engine in the longrun though, but you'd never have any real problems unless you beat on the car during hot weather, or have an FMIC or otherwise faulty cooling system.

I wouldnt really advise it for a rotary car, especially one with an old engine on original coolant seals.

 

At atmospheric pressure (14.7psi) water boils at 212degF, but at the ~28psi absolute pressure the cooling system is pressurised to the boiling point rises to 256degF.

Way too cold. Just go get the right one from Mazda.