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Discussion Starter #1
On my 00 Focus, I noticed that there is not much heat from the blower when idling or a slow steady speed. When I am on the hwy, it's fine, also fine when accelerating.
Coolant level is full and I have checked it a few times, not going down.
Thermostat is good, temp gauge and odometer confirm this.
T-stat and coolant new a couple months ago.

Could this be indicative of the pump going out?
 

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Discussion Starter #3
I am pretty sure it was 192. A Stant replacement of OEM.
The heat kicks out great while rpms are up, like driving 70mph down the hwy or accellerating from a stop.
Once you go to idle or cruise at, lets say 40mph, output drops noticeably, until you get back on the gas.

According to the odometer, cylinder head temp is about 85C when up to op temp.
 

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85C = 185F, so your thermostat would be closed if it's a 192F. If it's working right, then you should be able to see the temp rise to 95C or so, then drop back down to 85C when the thermostat opens. If you're not seeing that, then your new thermostat is stuck open, and that's why your heat is cold at idle. That condition fits your explanation of the problem as well.
 

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The same thing happened to me not too long after installing an aftermarket thermostat. I took it out and replaced it with the Motorctaft OEM TS and voila, heat at any RPM.
 

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Discussion Starter #6 (Edited)
I do see it go up to 90 and then settle between 88 and 83 while driving, usually about 85.
Once it gets to op temp, it stays there about 85C, independent of heat output.
 

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Discussion Starter #7
A little more info:
I just started it up cold, odometer read 12C.
Started driving, temp climbed to about 90C, then dropped to 83C.
Fluctuated between 83C and 88C, ussually about 85C while driving.
I had the blower on 2 and drove about 45 min, hwy and city.
When I got home, I turned the blower off and let the car idle in the driveway.
Temp went to 105C before the fan turned on and was continuing to climb until I started to rev the motor and turn the blower on.

What do you think?
Still thinking t-stat? If so, that's an easy one.
 

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That is where the problem lies IMO.
The therm for the heater core opens too far and allows too much flow to be bypassed. Then the main therm closes and you get good heat again.
The whole system is stupid on our cars IMO, just doesn't work well at all.

I'd found that if I remove the front heater core bypass hose, cap it off at the housing and the bypass tube, that I get good/reliable/consistent heat for winter; regardless of RPM or time running after warm.
 

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Discussion Starter #9
Where is this? I am assuming this is a heater control valve.
I have no issues with my Zetec, is this only for the SPI?
 

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WTH do you mean you have no issues?
Isn't this your problem thread asking for why and/or a solution?

zetec and SPI use the same thermostat BTW.
 

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Discussion Starter #11
@iminhell
Is this the thermostat housing or something else? A heater core valve?
I'm not sure where this part is. Parts list only show one t-stat and that is in the normal t-stat housing. I have replaced this.
I believe you are talking about a heater core t-stat and I don't know where that is.
I have 2 cars with both engine options and the problem only exists on my SPI motor, the Zetec is good.
I will take a look around the cooling system today to see if I can locate another valve or see what you are refering to about the bypass hose.
Sorry for the confusion.
 

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Discussion Starter #12
Ok, the t-stat housings are different. The pic is of the Zetec housing which threw me off.
 

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The thermostat and function is the same though. If you've replaced one you should have noticed that there are 2 thermostats on it, the rear one is for the heater core.



The distance from the back of the housing of the HCTcan have an effect on coolant flow.
 

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Discussion Starter #14
I picked up a new Motorcraft stat today, 192*.
I don't recall there being another t-stat in the housing.
I will install and use the car tomorrow morning. I will update then.
 

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Discussion Starter #15
Sorry, only one therostat in the housing for the SPI motor.
There was a small piece of metal in the housing that may have been keeping the t-stat stuck open or closed at times.
I am still skeptical that the pump is worn or faulty.
There was alot of sediment in this system when I did a flush a couple months ago.
I'll drive for a day or two and let everyone know.

Happy Thanksgiving Fanatics.
 

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Discussion Starter #17
I have heat!!!!
Finally had time to work on it and being a little warmer, 36*F the other day. I did another flush of the heater core and the system as a whole. New coolant and it's like a toaster over.
 
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