MARTIN

If thats the case, then you are saying that you only need the fan to idle. Which is certainly not the case... If I had a tag, I would love to do a lil experiment, but maybe you could do it. If you have an efan, why dont you turn it of anytime you are above 30 MPH.. I guarantee your car will run hot, if not overheat.

NZConvertible

Nope, the specified thermostat starts to open at ~180degF and is fully open at 203degF.

WTF? You just quoted me saying the fan wasn't needed "beyond 20-30mph". What part of that did you not understand?

Maybe that's what happens on your car, but it is not normal, and it indicates something is wrong with your cooling system.

MARTIN

nothing is wrong with my cooling system, I can assure you of that... I just dont get how you can say, that once you are at speed, you dont need a fan...

jono20

I determined my cooling problem to be the fan clutch. ive since swapped out the entire s4 water pump housing and fan assembly, and installed it into my s5.

I did run into the clearance issue with the omp, but I found that if you install the rubber rad hose FIRST, before tightening the housing bolts onto the engine, the hose gets squished againsed the OMP, and seals jsut fine.

the tube that goes to the BAC valve is in a different location on the s4 pump, and needs a 90 degree elbow to keep the hose from pinching closed.

can someone explain to me how the BAC valve uses the water coming from that hose? im not really sure what it does.

edit: ive also installed a low temp t-stat into the new housing..

NZConvertible

Why are you having difficulty with this very simple idea?

iceblue

There is no need for a low temp T-stat. If you reach your cooling capacity b/c of it you will begin to overheat. You should allways use a OEM T-stat.

MARTIN

Because, it definately not true...

Icemark

It only is bolted onto the bac to keep the bac up to temp and not freeze in cold weather.

Use only the Mazda OEM stat--- anything else will result in reduced cooling capability.

Icemark

actually the fan is usless above 40-45 MPH.

If you hook up a bypass relay that turns the fan off everytime you put it in 5th gear, (which is the way an electric fan should be wired- IMO) there will be no problems what so ever.

If you are overheating if you forgot to turn your fan on and are driving at 40+ MPH then there is a major problem with your cooling system. Fans are neither needed or used at 40+ MPH, if all your stock air flow panels are in place.

jono20

so with the hose bent a little, the flow wont be as good, but ill be ok to start up the engine?

jono20

a local rx guru here in town suggested I go for a lower temp t-stat (it was only a 180 btw), so I did

Icemark

No, the flow runs to the back of the motor as well

Icemark

\
Ah yeah.. a Guru... Telling you to use a lower thermostat???

The factory thermostat is 180F...

You should be using the factory thermostat. You will have overheating problems using anything else.

This has been proven over and over and over by members here and in the real world. I do not get why people don't understand this.

RETed

Too many people listening to the domestic V8 crowd...

Lower rated thermostats seem to be a big deal with them.
The cooler rating allows the water temp sensor to trigger the ECU to run richer.
This is why the engines make more power...more fuel.

The 13B's all basically run rich.
There's no reason to be running a cooler thermostat.
This will only make your car run richer and EAT MORE GAS.
If you don't mind paying more for gas (hey, 92 is going for ALMOST $3 / gallon over here!), then go for the cooler thermostat.
Running richer does not automatically mean the car makes more power.
In fact, in this case, it makes LESS power cause it's starting to foul spark plugs.

Just to throw in a wrench into this whole thread...
I run NO thermostat - just a gutted core.
With ambients in the 80F to 90F range, once the engine gets up to temp, it will NEVER go under 180F, according to my SPI Motorsports water temp gauge.
I mean I've had it idling over 10 minutes, and it's still hovering at around 180F.
Maybe if I let it idle for an HOUR or more will it drop lower, but I think the engine is at an equilibrium at around 180F.
This is with a STOCK radiator and an electric fan.
What does this all mean?
I think Mazda got their R&D right with the thermostat rating.
There is no reason to run a cooler one - the engine will almost never drop lower (unless we're talking ambients that approaching freezing temps, but that's ANOTHER thread).


-Ted