BigTex

iTrader: (16)

There is a good change you are right on with your thinking. You know, these trucks weren't really meant to have e-fans. The PCM supports it, but only partially. There is a pretty good chance that the PCM does turn the fans on at the AUX temp, but its alos possible that once its gets to a higher value where the main fans would be running, that it switches off the AUX fans to run the normal ones. To you and me, that means its turning off the main fans once it gets hot.

What speed were you seeing when you had your heating issues? I could see it happening on very slow uphill slopes and in traffic where there isn't much natural airflow through the radiator. However, if you keep 40mph+ speeds and have these issues, I think its something else.

(Ken)-Blown-383 4x4

On my truck I remove the pcm coolent temp sensor at the top of the intake....then add coolent and it will come out the sensor hole...then you know you have it to the top...then reinstall he sensor....also I would recommend a good quality 180 t-stat....160 can be used if you reset so closed loop comes in at a lower temp...but you will get a bit less mpg with a 160 unit.

BTW...t-stat works off solid/liquid wax which heats up and expands the plunger to open the valve...when a engine is overheated some of the wax can be forced out of the seals...after that happens the sensor will not open all the way!

Also, you might concider having an override manual switch like I do....also a good thing to have when you have a big intercooler up front like I do

Ken

thunder550

iTrader: (70)

Mostly 30-40mph, and yeah I just hooked up a wire to manually switch the fans. It really freaks me out when the temp gets above 210, even though the red mark on the gauge isn't till 260.....

I'm gonna try towing again with the fans switched manually, and if the problems go away I'm gonna hook them up so they're always on when the truck is running. I don't want to mess with it constantly....just want it to work!!
How long will the motors last with the fans running all the time?

(Ken)-Blown-383 4x4

No such a good idea to run them all the time...you alt. way go before the fans do.

You might concider running an aftermarket fan control switch?

Flex-a-lite PN...

Part #31147 - Adjustable Temperature Sensor
Turns fan on/off at the desired temperature. Dial-adjustable 1800-2400F. Gives the freedom to set one temperature for occasional high-demand use, then reset for highway or day-to-day driving.

Part #31165-VSC - Variable Speed Control
Attaches to or near the electric engine-cooling fan. Senses coolant temp. via the radiator core and sets fan speed from 60% to 100%, depending on built-in fan thermostat setting. Thermostat range: 155 - 220 degrees Fahrenheit. Allows greater control over engine temp: reduces charging spikes and current load on charging system. 25 amp max. load. Directs fan to run for 30 seconds after vehicle is turned off.

I run the VSC unit above and love it...it will also run the fan for about 15-20 seconds when you turn the engine off which helps keep engine heat soak down....also a lot easier on the charging system as it is a two speed system!

My buddy James B. wrote this article...which flex-a-lite features on there site
http://www.flex-a-lite.com/auto/html/vsc.html

Also this is the setup I run on my 383... flex-a-lite 295 fans and a 2" aluminum Howe radiator...fits perfect inbetween the Ford 7.3L turbo diesel intercooler Notice the flap covers which open up when at freeway speeds but close tight when the fans come on!


BTW...hows that exhaust system sound under boost?? If your sound goes away and you start to hear a jet engine rush of air instead you have to much back pressure...with 8psi of boost on the old 350 engine at 4K it did this and I had 6psi of backpressure even with a bigger aftermarket exhaust...reason I run a dual 3" to a single 4" diesel magnaflow muffler....new system has less that 2psi of back pressure.

Ken

thunder550

iTrader: (70)

Exhaust still sounds fine...I have a 200 amp aftermarket alt too, you still think it will be an issue? The fans don't draw much on low...I think my voltage drops by about .2 when they are on. I could understand wearing the alt out if the fans were on high all the time, but on low they are relatively low draw.

I don't see the flaps in your pic.

(Ken)-Blown-383 4x4

Good on the exhaust then...if you bump up the boost you may notice it...at about 4 psi of back pressure is when you will start to hear it....I knocked off over .5 seconds on my quarter mile times just by upgrading the exhaust system.

If you left it on low that should be ok...I was thinking about adding a switch to do that on my setup so the IC would stay on the cool side...esp in the summer.

Rubber flaps...top right, bottom left.

parish8

iTrader: (6)

i have never burped my coolant and no problems, same with my old truck and it was a boosted 6.0 ext cab and i towed thru the rockies a few times with no temps over 210.

i would suspect the fans shuting off or at least just running them on low isn't enough. crank them thing up to full.

thunder550

iTrader: (70)

OK did a few test runs towing up the hill...here's how they went

1st run: PCM wire manually triggered, no a/c
2nd run: PCM wire manually triggered, a/c on
3rd run: Fans triggered by PCM, a/c on

There was almost no difference between the three pulls, all three times the truck got up to 225 or so. Damn, eliminated the easiest fix. I'm going to replace the t-stat next week and see if that helps. Is one t-stat as good as the next? Can I go get one a Autozone or Checker or should I get an OEM? I don't want a lower temp thermostat...started a thread awhile back asking the advantage and the conclusion seemed to be that they will do more harm than good unless you have a multi-core radiator to support the lower temps. I want to stick with the original temp t-stat.
https://ls1tech.com/forums/showthread.php?t=314872

Ken - I see the flaps now, I am retarded sorry.

white1

iTrader: (5)

I havent got a tune to turn my fans on yet, ao I used a temp controller from Pep boys. It works great most of the time, but it seems like every couple of weeks the turn on wire quits turning on, and I get a little hot cause my fans arent on. I just jump it with my power wire and it works fine. Sometimes they stay on a minuite after I turn the truck off, but after it did it to me again today, I think I'll just leave it this way till I get my tune, and harness.
My fans are eigthor on or off. No low/high,one fan two fans. They are eigthor both on high, or both off. I don't have any problems getting hot except when the turn on wire flakes on me.

one03sierra

iTrader: (1)

did you ever check that upper hose. i would do that first. that sucker caused me a few headaches.