This has just started recently with no modifications or anything. In the morning when I'm leaving work (5:50am, around 50 degrees), I usually let the car warm up for about a minute before I leave, and have never had a problem. Lately I've been having to to let it totally warm up or I have problems.

Problem #1: The car will heat up to almost overheating levels during normal acceleration and driving. After a while it will settle and I will not have a problem with it again until it sits overnight.

Problem #2: I will press the gas and the car will go, but there is a random hesitation where the engine sounds like its cut off from fuel and I lose all power. It will last maybe 2 seconds before it kicks back up. Again, will never happen if the car is warmed up.


I don't have a problem letting the car warm up, but that's gas right there...

88 base coupe, n/a, taurus fan w/ thermoswitch are the only mods. The fan regulates the temp wonderfully when the car is at temp.

Any ideas?

 

It's that shitty motor you got in there! J/K ( I hope I'm joking!)

Problem # 1) Sounds like you might have a stuck or sticking thermostat. Or possible air in the system. The FSM has a coolant system bleeding procedure.

Problem # 2) I am not sure if it is an electrical problem (a sensor or switch that activates /deactivates based on the temperature) Or possibly a mechanical issue that is directly related to the temperature (ex. something that seals better when warm)

I would check the ECU pinouts when the car is cold, and again when it is warm. Compare these to the values in the FSM. If you find something wacky, then that narrows down the problem a good bit!

If this does not turn anything up, It may be time to explore mechanical issues.

 

That's just a tad bit overly complicated.

Try this:
With the car off, and the pressure relieved from the cooling system, take off your radiator cap and EGI fuse, turn the car over, and check for any coolant spraying out. That indicates blown seals. I think your car just needs to be burped to fix the coolant issue.

If it's an S4, there is a bleeder screw on the passenger side of the radiator on the top. When you're filling up the system, remove that screw carefully and screw it back in once water starts pouring out. Then keep your car on until it warms up, while having the heater on at full blast. Top the coolant off, put the rad cap back on, and you'll be good to go. (Assuming there are no leaks and your coolant seals are fine.)

It it's an S5, do the same but without the bleeder screw, Mazda removed it in that series.

 

lol.... No it's been good to me up until this point.


Ok... another thing that may help. I have a thermoswitch installed. The instructions told me to feed the probe into the upper radiator hose. After I initially set and adjusted it, I have never touched it. It ran fine for couple weeks after that. Now the temp gauge is saying almost 3/4ths but the fan is kicking on at the same time it always does...? Is that the ideal location for the probe or should it be somewhere else?

 

And one more thing I just noticed. I was refilling the coolant and I put my hand over the opening for the cap. I squeezed the hose and when I did, I heard a rattling. I put my ear down there and its coming from the thermostat housing. I'm guessing thats not supposed to happen.....

 

Noo, thermostats are *not* supposed to rattle. They seat in between the filler neck and the water pump really well.

 

Well I wouldn't call it a rattling really... It reminds me of a check valve. Thats the only way to describe it. Well... I'm going to pick one up from the dealer regardless.