My installation included a compression style adapter. The thermocouple itself was not threaded and was smooth. The adapter screwed into the pipe threads with a compression type of nut on the outside. You slide the thermocouple in as far as you want and then tighten the nut to hold it in position. I suppose I could "play" with it to see if positioning makes any difference, but I just haven't taken the time to do so.

 

That sounds like a good system. The x-monitor thermocoupler is threaded, and extends approximately 1.75 inches beyond the end of threads, if I remember correctly. I should check the thermocoupler to see if it is adjustable...

 

That was one of the advantages of removing the manifold to do the install, I could verify that I have no clearance issues.

The reason that the temperature drops while decelerating is that more cool air is being pumped through the motor. The motor is reving between 1200 and 1800 RPM or even higher depending upon tranny conditions and the T/H mode selection. The fueling going to the motor is only that which is sufficient to support idle conditions, so there's more cool air going in there than heat being generated.

After climbing a mountain grade for 10 minutes or more while pulling the trailer at EGTs from 700 to 1150 deg the temps will immediately decrease as I head over the top of the pass and down the other side. I've seen the temps drop to as low as 120 or 130 deg while the T/H mode was holding the truck back going down the hill. The motor was spinning at around 3000 RPM and the outside ambient air was 70 or 80 deg. So the air was only seeing a 50 deg heat rise or so through the motor.

Once I got where I was going and pulled in to the parking lot to check in to the camp ground, after climbing back in the truck after a few minutes, the idle was right back to the low 300s.

Hope this helps,

Daryl

 

250-275 idle
750 cruising with a trailer that isnt in the wind (70hp)
1250-1350 in a hard pull w/o water(70hp)
950 in a hard pull with water (70hp)
900 in a hard pull with WWF (70hp)
1400-1500 no trailer WOT (125hp) no water
1100 max no trailer WOT (125hp) with water or WWF

 

Those last two correspond well with mine...I am seeing about 275 to 300 degree temp drops on pure water alone, closer to 350 loaded with windshield washer fluid or ice, possibly more if I went to a 30/70 mix AND ice, maybe close to 400, I need to try it. With a new intercooler and the water, I think we could run the stock injectors at full blast and still keep the EGT's down.