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Discussion Starter · #1 ·
My PCM is programmed for 160 degrees. I think my thermostat is bad and was thinking of putting a 180. The car just never gets hot, especially in the Winter (temp gauge and heater).

Has anyone done this and were there any problems?
 

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Discussion Starter · #3 ·
Ah, I was afraid of that. Guess I'm stuck with a 160 thermostat since I have no way of reprogramming my PCM myself.
 

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My experience with a 160 degree 'stat and programming is that your gauge will read about 1/4. However, your heat should be reasonably warm. Sounds to me like you have a clogged heater core.
 

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Discussion Starter · #5 ·
My gauge gets to about 1/8 and then stops. Never goes higher.

I'm going to connect my AutoXray today and see what it says.
 

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Discussion Starter · #6 ·
Well, I connected my AutoXray this morning for my hour long daily drive. Within minutes the temp read 150. After about 10 minutes (still sub-50mph driving), it hit 168. After being on the freeway cruising at 73, it fluctuated between 169 and 174. Neither fan ever came on.

It takes about 30 minutes of running the heater on full to warm the car enough that I even think about unzipping my coat and taking my gloves off. According to the scanner, it was 39 outside.

Something else that was odd is my speedo read 73, but the scanner read 77/78. I would have thought those two numbers would match. Seem like the difference starts at about 23mph on the speedo where the scanner shows 24.

So, are those temps enough that I should get more heat than I am (meaning I should flush my heater core)?
 

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Take two otherwise identical B-bodies. Equip one with a 160°F thermostat, the other with a 180°F.

Drive them under the exact same conditions (pretend this is possible). Say, your freeway scenario, which I will assume stayed above 40-something MpH, as the fans never came on. That's because the PCM was programmed to leave the fans off above 40-something MpH because at or above 40-something, nature exceeds the fans' performance, making them redundant.

The one with the 160°F thermostat begins to open @ 160°F, and FULLY opens by 175°F.
The one with the 180°F thermostat begins to open @ 180°F, and FULLY opens by 195°F.

To make it short, the car with the 180°F stat will blow air through the heatercore @ 20°F warmer than the car with the 160°F.

3) For the winter, you can take off the airdam under the radiator.

4) Hook up your AutoXray, disconnect the fans, and watch the Coolant Temp Sensor's readings rise while operating the passenger heater fans.

(Reconnect both fans before your CTS reads 230°F.)

If, compared to your present heater's performance, you don't notice a significant improvement in your comfort levels before the CTS reports 215°F, flush, backflush, and reflush each major component of your cooling system separately (this would be the ideal, so that you don't force contamination from one part into or through the other).

If it does improve, then your heatercore's performance is just being held back by cold coolant.

Several years before the GDL, a date told me to turn back so we could use her car, as her heater 'wasn't broken like mine'.

Since then, I use a 180°F thermostat with appropriate fan settings for the winter.
 

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Well, I connected my AutoXray this morning for my hour long daily drive. Within minutes the temp read 150. After about 10 minutes (still sub-50mph driving), it hit 168. After being on the freeway cruising at 73, it fluctuated between 169 and 174. Neither fan ever came on.
It takes about 30 minutes of running the heater on full to warm the car enough that I even think about unzipping my coat and taking my gloves off. According to the scanner, it was 39 outside.

Something else that was odd is my speedo read 73, but the scanner read 77/78. I would have thought those two numbers would match. Seem like the difference starts at about 23mph on the speedo where the scanner shows 24.

So, are those temps enough that I should get more heat than I am (meaning I should flush my heater core)?

My primary fan is programmed to turn on at appox 181-182 degrees with my 160 t-stat (pcm4less tune). It gets there no problem if it sits in traffic long enough. While driving around town, it never goes any higher than approx. 177 degrees. On the highway, it will go as low as 174-175 degrees.

The temp. needle sits just below the 1/4 at 175 degrees and just above the 1/4 mark at 182 degrees.
 

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Quick check of the heater core: Grab the inlet and outlet hoses near the firewall once the car is fully warmed up and idling. If one is noticably cooler than the other, your heater core is clogged. When flushing, its also a good idea to go ahead and replace the restrictor as well.
 
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