Won't warm up

[TominMO]

1. The heater core gets fresh coolant regardless of the thermostat flow. That's why there's that little bypass nipple right before it that joins with the heater return coolant and goes back to the water pump.
2. Blocking the flow to the rad guarantees that no ambient temperature coolant finds its way back into the engine. So the engine can actually hold temperature like it should

1. Right, that I know. The water pump pushes coolant thru the head and heater core. The heater core coolant goes back to the WP via the bypass tube. The coolant that goes all the way thru the head exits past the t-stat, thru the housing and upper hose, to the top of the rad. Gravity and pressure take it out the bottom hose and back to the WP.
2. Blocking the flow thru the top hose to the radiator is what the t-stat does for a living; if it is functioning correctly, nothing else needs to be done to this cycle. So the solution lies elsewhere. Blocking rad airflow, insulation, etc.

Or maybe sticking in an Aspire heater box/heater core, which is larger.

[bhearts]

1. Right, that I know. The water pump pushes coolant thru the head and heater core. The heater core coolant goes back to the WP via the bypass tube. The coolant that goes all the way thru the head exits past the t-stat, thru the housing and upper hose, to the top of the rad. Gravity and pressure take it out the bottom hose and back to the WP.
2. Blocking the flow thru the top hose is what the t-stat does for a living; if it is functioning correctly, nothing else needs to be done to this cycle. So the solution lies elsewhere. Blocking rad airflow, insulation, etc.

Or maybe sticking in an Aspire heater box/heater core, which is larger.

aren't thermostats linear based devices, it's not an on/off switch. Springs starts to warm up, let's very small coolant by, rated temp coolant hits the spring, max flow gets by. Not saying the man doesn't have an actual problem though. Hopefully a flush helps alot.

[Gordon12]

Well I think that was it. Just finishing up, and than I will see how she is in the morning when she is nice and cold. But wtf is this kind of thermostat?

[Festivahopeful]

From what I understand our Mazda engines use a two stage thermostat, the little spring is the first stage and will let a little coolant through when warm, when the big one warms up it allows full flow. I would suggest getting another OE two stage thermostat because I have heard that a cheap one without the secondary passage can lead to cold running as well. Anyone correct me if I am wrong since I am still learning.

[TominMO]

I'd replace that one with a new one. Looks like it's been in there a while. Not convinced that two-stages do better than the normal single-stage. I just buy the better of the two Stants at the McParts store. Only slightly more expensive, and better materials.

[Gordon12]

Mazda engine? 1.8 is a mazda engine? I replaced it, new one had a shorter spring, and didn't have that second part. Old one was slightly stuck open to.

[TominMO]

Stuck open = never gets warm enuf.

Edit: Just ordered four t-stats from Rock Auto. Three are Motorad "open when fail" t-stats, and one is a Motorad two-stage; all of them are 192 degrees. Gonna try the two-stage in my B6 Festiva, then switch to the fail open one to see if I can detect a difference in interior heating. I suspect not, but we'll see.

[bhearts]

yep, thatll do it. that color was nasty. i hope your detergent flush did some work on that coolant system. thats what the diesel guys use.

[jason_]

See, just a lil guy.

Jesus. Just put the radiator in the cab?

[Movin]

Make sure the t stat is dead center in the housing and that the housing surfaces are flat. Any part of old gasket, any warp of housing or any slip of the stat off center will cause a warp to happen to the t stat and it will not seal when the engine is cold. leakage here slows engine warm up a lot, causes it to run rich, makes your oil go bad very fast, causes carbon build up and makes your heater suck. Put it together right so that all the systems can work good like its supposed to. These things are awesome but all it takes is thirty years plus and our lack of excellence to make us wonder whats wrong lol.

You have done awesome in getting the insulating grung out, that kicks south side of north facing subject big time. If you really need heat you can reset all tune up specs for winter conditions with the exception of ignition timing retarded about 4 deg behind specs. This will cause more combustion heat to conduct to the cooling system. It will not help MPG at all but so what, gasoline is cheaper than heating fuel right now lol.

Have fun, these things are awesome and Oregun rocks!!

[WmWatt]

I guess we all know now the thermostat doesn't have to open for the heater to work. I'm pretty sure the reason for that is so the defroster can clear the windshield as soon a you start driving.

[Gordon12]

Yeah, it's definitely in there flat. And I'll know tomorrow when I drive to work if she warms up right away, or it was a failed attempt. But I have a decent feeling about it. I'll have to check my timing, the distributor looks maxed out. And when I changed my plugs, they were all white and chalky.

[Gordon12]

Idk how well the detergent worked, the surfaces were still pretty brown.

[Gordon12]

Well it was a lil bit warmer out this morning. But I think it still helped. The gauge actually warmed up to this point in a mile of driving instead of barely coming off cold after 20 miles of driving

[bhearts]

o shoot, thats really impressive. just a mile, or two...