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Discussion Starter #1 (Edited)
I recently replaced my t stat with another oem one (201 degree...I ordered a jet 180). Here is my question while I wait on the Jet t stat: my fans seem to be running more than they did before w/ the old t stat. On average, things are about 10 degrees hotter. e.g. used to settle in at 194; now its 204, peeking at 210.

I guess I am wondering what the stock LS on/offs are and HS on/off are? I can def. hear the HS fan now.

When I plugged in my DS tuner, and looked at the fan settings, I am assuming it is not reading what they currently are as the LS on was 211and HS fan on was 226. it never gets that hot.

Do I need to adjust the fans in the interim? The Jet should be in Saturday or Monday.

Thanks for the help,
Randy



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Discussion Starter #2
Some pics when I plugged in predator:
LS ON:
ImageUploadedByAutoGuide1366330006.911675.jpg
HS ON:
ImageUploadedByAutoGuide1366330019.475117.jpg

Under the AC OFF:
ImageUploadedByAutoGuide1366330082.055901.jpg
ImageUploadedByAutoGuide1366330094.939522.jpg
ImageUploadedByAutoGuide1366330107.739242.jpg

Do I need to changed these with the current 201 degree t stat?


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Discussion Starter #4
Thanks for the post up....so, you think the Predator is reading the actual temps, then? They seem to turn on well below those temps....and I've never adjusted them!

What would you suggest for the stock tstat?

Thanks!


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No..what you are seeing on the Predator is the default Predator settings for the fans, not the actual coolant temperature or actual fan settings. You will be adjusting them down from those settings.

It may be that your old tstat wasn't stock (I'd guess it was a 190 - 195 deg.F unit) and it doesn't sound as if your new stat is opening at 201. You can adjust them down if you want and for now, until the 180 stat goes in, I'd set them at 205 deg. F LS fan all conditions; 210 deg. F HS fan all conditions.
 

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Discussion Starter #6 (Edited)
^^And that is exactly what I needed to know! Thanks.

The Jet looks to be in tomorrow so I will swap it Saturday morning.
This screen;
ImageUploadedByAutoGuide1366342656.938418.jpg
All The HIs should be the same.
All The LOs should be the same, correct?

Thanks bud!!


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Whether or not to put all the LS & HS fans at the same settings, what those settings should be and what the spread should be between the two fan types has been a matter of much debate.

However, some practical application of knowledge and taking into consideration the ambient conditions you will likely encounter in your area will hep with determining those settings.

First, it makes no sense to set the fans near, at or below the tstat opening temperature. If you did, the fans would never shut off.

Secondly, setting the fan temps at their stock settings invalidates having the lower value tstat.

Now we have a range...185 degrees to 203 degrees, which is 5 degrees above the tstat value (as close as you want to get to avoid running a LS fan all the time) and the exact temp at which the stock tstat opens. Now, remember there is no real issue with the engine running at 203 degrees or above because that was set for emissions purposes. However, what temperature is too high before you start seeing HP robbing heat soak begin? Your guess is as good as mine but in my practical experience, once I hit 215 degrees, my 6.1L starts to get weak. Alternately, if I keep it at 205 or less, it runs great.

Also, consider stop and go traffic. Engine temps will rise faster in such conditions but in stop and go, you don't need HP...you need patience. So setting the fan temps too low if you encounter this condition routinely, especially in high ambient temps, and you will wear out your LS fan.

Now, consider the fact that your coolant temperature at freeway speeds will normally be lower than when you are running around town, due to airflow across the radiator and around the engine.

So how does this all add up to a formula for setting your fans? It doesn't. It just describes the variables you get to consider.

Bottom line for me was to set my LS fan at 194 degrees all conditions (keeps me from burning out a fan in stop and go + is a good temperature for preserving a cooler running temperature) and 201 HS to keep me below that 205 degree threshold I mentioned earlier.

YMMV
 

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And add to the above that other things trigger the fans. One is AC high side pressure, also trans fluid temps.

I have run 185/195 for years down here in hot climate with no issues.
 
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Discussion Starter #9
Got the Jet in and set all fan speeds to 194 LS and 201 HS. I am assuming the screen with the low mph speed and high mph speed fan settings are the same?
ImageUploadedByAutoGuide1366469386.856660.jpg
I set ALL LSs to 194 and ALL HSs to 201.

Thanks fellas.


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That's a good starting point.

Now, pay attention to coolant temps when the fan comes on, goes off, the ambient temperature and driving conditions (stop and go, slow cruise, freeway speeds) and you can always tweak from there.

Also, make a note of your coolant temp when running at freeway speeds at different ambient temperatures. It's always good to know where the car should be running temp wise just in case.
 

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Discussion Starter #11
^^^^so.....here's where I'm at: after a week of various driving conditions and my fans set at LS 190 and HS 197, I found that my LS fan, while on the high at higher RPMs (hotter engine) seemed to be on all the time. The wierd thing is that the temp literally stayed right at 190 degrees on the highway - it really didn't fluctuate until I exited, etc. Not sure it this means anything - maybe it's good.

I then bumped up the LS to 193 and HS to 198. Thing is, my temps have never gotten anywhere near 198...of course its spring in MI and in the 60s.

Should the HS fan be a certain number above the LS, like 7 or 10 degrees?

One caveat: the LS fans seems to stay on until it cools about 7 degrees. i.e. fan comes on at 193 and shuts off at 186. So, I figure if my temp never hits 186 on the interstate, is it save to assume my fan is on, all the time its over 186 (if it hit 193, which is the LS fan setting)?

Yikes. Not sure if any of that ^^^ makes sense!!

Current LS 193
Current HS 198

Thanks MD or whomever....

r.


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Hey Everyone,

Just replaced radiator in my 5.7L.
Replaced TStat with 180.
Lowered Fan settings to LS 190, MS 195, HS 201.

Tested and thought I was all set. Both fans turned on at 190.

EXCEPT Now after a short test drive, only the driver's side fan is spinning.

Could this be a coincidence????

Temps were between 187 and 194 the entire city drive with a brief sprint on the freeway.

I live in AZ, it's 75 degrees today.

Thanks in advance.
 

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...went back out to garage to check those fans, both with and without the AC on - just to see...

Both fans running at 185 temp, both with and without AC on.

Go figure - any further details on the fan operation would be super appreciated.

Thanks.
 

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From what I hear, +\-5 degrees on fan start temp is normal. Can you confirm that the fans should either both be on or both be off if/when running?

Also, any pro tips to removing the air bleed tube without spilling coolant all down the front of the engine when filling w coolant?

thanks.
 
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