A slightly different thermostat question

[Mike McKown]

Briefly..............

My heater puts out warm air only and it seems to cycle between warm and luke warm.

I flushed the heater core by removing both hoses and turned the garden hose in the core. There was no trash or sediment expelled, I.E., clean.

It seems to take about 2-3 miles of driving before you can get any heat out of the heater and then it is just luke warm.

So, I pull the thermostat. It's an OEM style. Temp rating stamped on it says 85-88C which is roughly 185-190*F.

I'd also add, the thermostat was rotated 90* clockwise from where it was supposed to be.

I drop the thermostat in the pan on the stove for a check. No thermometer but the water had to come to a full boil to open the main port opened up. It was difficult to tell when the small one opened but it opened just a tiny bit at about the same temp.

Any idea why no real heat out of my heater? The engine never appears to overheat, lose coolant and the cooling fan runs very little.

Called the Ford dealer today, they want $31/change for a thermostat. Mazda wanted about $36. FWIW, neither place showed much interest in getting the part either. If I hadn't had the part number, I likely wouldn't even have gotten a price.

[perucho]

Wow, that sounds pricey for a thermostat! Maybe someone here can get you one cheaper? Hopefully just replacing the t-stat gets you warm(er) air.

[eurotiva]

How cold is it where your at Mike? Sitting still does it still cycle as much?
Someone here will know what to do to help. As for me I have to know more about a/c blowing cold 8)

Maybe some cardboard over a portion of the radiator to stop airflow.

[bhazard]

Rockauto has the stats for like $20.

[m715]

Motorcraft Part #RT 1073 $18.17 each at Rock Auto. Gasket is incuded in the box. Be sure to get that thermostat in the correct orientation to avoid snapping off the housing. I talked to a guy today about the same issue.
You can use discount code 2358435881690 until 12/10 in the "how did you hear about us" box at checkout for 5% discount.

HTH

Michael

[Mike McKown]

How cold is it where your at Mike? Sitting still does it still cycle as much?
Someone here will know what to do to help. As for me I have to know more about a/c blowing cold 8)

Maybe some cardboard over a portion of the radiator to stop airflow.

Today, it was 60* here. The last week, it's been in the teens/twenties. I doesn't make much difference in heater output no matter what the ambient air temp is.

The thought has crossed my mind that the thermostat is opening at a higher temp than when the fan turns on. So when the water starts to flow, the fan cools the coolant off and slams the thermostat shut. Maybe far fetched but I can't think of anything else.

To you other guys offering lower buck thermostat sources, I'm more interested in fixing the problem than what it will cost to fix it. If I buy another thermostat, it looks like the Rock Auto piece is the best buy based on what I've seen priced. But thanks for thinking of me.

I have three other Festivas that have a toasty warm heater. They'll run you out of the car on a really cold day.

[GenevaDirt]

are you sure your water pump is circulating the water? Drop in a new thermostat. I know some will argue with me but I have no problem with say a 89 323 thermostat and they are dirt cheap....not even 10 bucks. Get the higher temp one....195 I think ...if they have it. See if that helps...if not....you may have a circulation problem. Or...the heater core could be clogged around the outside with a mouse nest or something...not letting the heat actually dissipate as the fluid runs through.

[TominMO]

Maybe your heater core is getting blocked? Try radiator flush in the system.

When you get a thermostat, get a good one. I had one in my Subaru which was a cheap McParts one. I replaced it with an aftermarket one from some online store. I also got one from the dealer. The dealer's was the most serious looking; the online one was pretty good; the McParts one (Stant I think) was flimsy.

[Team Lightning]

When the temp has been in the lower teens and below, I have seen my Festy take 20 miles before it would warm up into the normal zone. That's with the factory Thermostat.

[GenevaDirt]

Maybe your heater core is getting blocked? Try radiator flush in the system.

he has mentioned he flushed the core with the hoses off at the beginning of the post.

[m715]

There is one other possibility, and I wish I could give you a more concrete solution. I know an engineer that has a festiva here that went for two years without heat. The guy is VERY bright, but the lack of heat winter or summer stumped everyone we knew. All I can tell you is that it was a blockage SOMEWHERE in the system that never caused a single problem other than a cold running car year round. After repeated flushings while trying to pin down the problem, incuding totally bypassing the radiator at one point (YIKES!!) the blockage finally came loose, and now he has a warm car this winter! I still question the bypass tube coming into the picture being he never could get the engine to get warm under any circumstances, and you could hold your hand on it long after it should have too hot to the touch. The blockage is in the block/head?

Michael

[Mike McKown]

When the temp has been in the lower teens and below, I have seen my Festy take 20 miles before it would warm up into the normal zone. That's with the factory Thermostat.

One of my other Festivas blows warm air after two miles or less when it's really cold. Thanks.

[Mike McKown]

There is one other possibility, and I wish I could give you a more concrete solution. I still question the bypass tube coming into the picture being he never could get the engine to get warm under any circumstances, and you could hold your hand on it long after it should have too hot to the touch. The blockage is in the block/head?

Michael

This was going to be the next place I investigated as I don't seem to have consistent temps between the top radiator hose and the heater hoses. Thanks.

[m715]

Mine vary from one to another some. The crate engine heats the fastest which makes me wonder if the iron block/aluminum head causes some galvonic issues in the cooling passages. This could be especially true if the coolant was neglected for any period of time by a P.O.

Michael

[m715]

Oh..... sounds like what he had. He used to get frustrated by the inconsistancy, and tried many different ways to track it down.

Michael