Hello all,

Like many others I am in the process of getting some sort of decent heat from my FD during my winter commutes. I followed all of the instructions I have gathered from here (coolant flush/heater core flush). This helped a little bit but the car is still pretty cold most of the time. I have also tried to add a higher mixture of 100% coolant in an attempt to get the car to stay at a warmer temp but it wasn't much help. My reasoning for a new thermostat is the car takes forever to reach operating temp and even in stop and go traffic it struggles to keep warm. If I'm on the highway with the heat on I can literally see the stock temp needle go down and then the once warm heat quickly starts turning into a cold breeze. My final clue was if I shut the car off for less than 30 min it completely cools down to the point of having to go into accelerated warm up. So guys does this sound like the symptoms of a sticking thermostat?

 

You can definitely check and possibly replace the actual coolant thermostat. However, if the eshaft thermal pellet was eliminated by your builder (and it probably was unless it's a reman) then slower warmup times are inevitable in this kind of weather. The thermal pellet is behind the main front bolt and limits the oil flow through the eshaft. It prevents the eshaft from spraying cold oil on the back of the rotors, which helps warmup times. Unfortunately this unit can fail, and most builders basically delete it rather than install a brand new OEM one.

So if you have an engine that wasn't built by Mazda it's probably spraying cold oil on the rotors which contributes to long warmup times.

 

Sounds like the t-stat is stuck open. It isn't difficult to replace, and the part is not expensive. I would replace it. It may not help your heater problem.

 

Well I purchased the car from Fritz a few years ago. We ended up putting a low mileage stock motor in which to my knowledge was all factory original. Could the coolant thermostat have anything to do with the prolonged warm up process and unstable engine temps?

 

Remove the thermostat. place it in a pot of water in your kitchen. Set the burner on high and put a thermometer (a meat thermometer will work well enough) in the water. Verify that the valve stays closed until approximately 180F/82C. At this point it should slowly lift until 203F/95C where it will be fully open.

 

If you are going to test it might as well replace it as well. But make you buy an actual mazda part

 

I just picked up a thermostat from Ray that Ill install tomorrow. Ill also post the results for those who are interested.

 

Having the same issue. The only logical reason would be the thermostat so im hoping it works for you.

 

I thought that a higher mixture of water helps to add better heat (for inside the cabin), not higher content of coolant...

 

Well I know that water has a higher cooling efficiency than coolant. So running more water would keep the block cooler thus not allowing enough coolant to pass through the heater core to keep the cabin warm.

 

Water/coolant mixture will not make a significant difference in how your heater operates.

 

That's correct but more coolant should allow for faster warm up.

 

You should of called me man I'd of hooked you up with a new thermo CHEAP

 

Water has a higher specific heat capacity. This is why it cools better as it absorbs more heat from the block then just coolant does. Theoretically because the water absorbs more heat from the engine it could give off better heat from the heater core, but I doubt you would really be able to tell.

 

What I've found from running around in track car type setups is the more efficient the cooling capacity along with the more water I run the colder the cars heat is and the longer it takes to warm up. My current track car will barely start heating in my 15 minute drive into to work because of the v mount setup big oil coolers and high water content. If I ran all coolant it would heat up much faster.

 

Well I just replaced the thermostat with an oem one. The one that was in there was much bigger than my new one so I'm assuming it was a generic replacement. The install went pretty easy but I noticed a few strange things while driving. At first the heat was great then the stock temp needle fell almost to nothing and the air became very cold. Next the car started to over heat but even with the heater on full blast it didn't help slow the process down at all. This is the first time that the car has even come close to over heating and it has me very worried. I'm assuming there might be some air in the system so I will let the car warm up again with the cap off and pore water in if needed. Unless this sounds like something else could have gone wrong. Fritz I totally forgot, you probable have a million of these things laying around. Its okay I think Jennifer will be calling you about a PFC for christmas!

 

definitely check for air in the system. It's not easy to get it all out on an FD.

 

Typically if you're having bubbles or didn't put in enough coolant the buzzer will go off but yep that's likely why you're now starting to overheat. If the car is still geting hot then cold you could have an issue with the heater core itself possibly being clogged.

A great way to burp the system is to remove the coolant hose to the t body and continue to top off until coolant comes out of the hose. Squeezing the rad hoses will speed up the process.

Sounds good on the PFC

 

Yep no coolant light but the needle did get pretty close to the "H". There was this strange sizzling sound coming from the T-stat housing when I shut it off. I'm just hoping no long term damage has been done..

 

that sizzling is your coolant boiling bro

 

Similiar issue when I installed chargespeed vented hood and removed ac condensor infront of my 3 row radiator. My temps were 140-160 degrees on the freeway and on the street would stay at 180. Replace the thermostat and see whats up.

 

While following up with another heating issue thread, i think it might be worth checking if your actual heater core is clogged.

That of course is if burping the system does not work.

 

Are you sure you didn't install the t-stat backwards?

 

I just ordered a koyo radiator and I'm going to change my t-stat as well, let us know when u figure it out so if I run in to the same issues I can have the fix in place. Thanks!

 

Well after a bunch of head scratching I decided to take every thing off again and check the new thermostat. Wallah! The ring gasket that was supposed to be snug around the thermostat had wiggled it self off so the thermostat was basically floating. After it was re-installed correctly, filled with coolant and burped the change was great! The car is warming up much faster and now the heater is 10X better than before. Now my feet are literally starting to melt with the blower only set to 2! If you have already flushed the heater core with little luck I would highly recommend replacing the thermostat.