NA 3B EGT numbers

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Dec 16, 2010
The Northern of Va.
Okay, finally got my EGT gauge wired in and hooked up. Went with the Auber gauge and really like it but have to say that now that there are numbers there, Im a little distracted. I drove it home like I normally would and was surprised by the numbers. At speed (65 mph) in 5th on flat, 500- 600F. Add some incline to the equation and it jumps up pretty quick. Just driving it like I have been for months, I saw 1300 and up when going up some inclines. I give it some pedal and the usual black smoke comes out and the temps start to climb. Once Im at the top, the smoke is no longer visible and the temps immediately start to drop back into the 500-600 range. At idle (cold), Im in the teens to mid 200s. At idle after a highway run, Im at around 310 but within about 15 seconds, Im below 300 and settling in. So, I know that the danger zone is high 1300 to 1400 but I am surprised at how easily this number is to reach. It really doesnt take much. Leaving a light and shifting at 2300 to 2500 has me at 1100 to 1300 easy.

The truck runs great. Idles smooth (for a diesel). No smoke unless Im accelerating and then its black. Doesnt run hot at all. Great oil pressure (50- 60 psi warm at about 2500 rpm). Great compression numbers. Great mileage (17-18 city and have seen 24 hwy) for the build of the truck. The EGT numbers, now that I have a gauge, seem fine when running around but it is oh so very easy to get into that high zone. The moment I clutch, the numbers immediately start to drop and I can downshift and sort of control the numbers but then the speed drops of course. Does all of this sound right? Is the danger zone a sustained ______ (fill in the blank) degrees F or if it even appears on the screen?

Not turbo'd (yet), H55F, 4.11 gears, 32s, ~2.125" exhaust from manifold back.
EGT on a non turbo diesel aren't a huge concern, you'll be blowing lots of black smoke before you'll hit engine damage.

It's the turbo adding heat to the intake and pressure to the exhaust that lets you reach truely dangerous temps.
And that's why we go to a bigger exhaust when we turbo. A small(er) exhaust and a long run will really create alot of back pressure, my guess is a NA 3B could run a full length (with muffler) 2.5 exhaust and you'd see those EGT's drop a bit.

Sounds also like your fuel is set high. I never had black smoke when climbing big hills before turbo (bt) so you're introducing more fuel than you really need to and I bet if you turn it down (in) some you'll get the same response from the truck with better fuel economy (and lower EGT's to boot).
My numbers are exactly the same as your in every incident. On the highway I'll peak at 1350-1375 when I'm running the truck hard up a hill. I don't blow black smoke unless I do a hard rev-matched downshift, or romp the throttle a few times in neutral. I was told a few times that it is not abnormal for N/A diesels to see quite high egt's on the highway. I would also like to know if these numbers are normal, or if my timing should be adjusted.

I've got a 1984 BJ60, N/A 3b with the H55f. SOA running 35x12.50's, 4:88's, ARB front bumper, 3/8 steel rear bumper with full size spare. Big roof basket, winch, and storage boxes with tons of gear. I'm running Auto Meter EGT. Water temp, and oil pressure gauges.
Excellent. Im glad that these sound okay. Where is the fuel adjustment on the pump? The last time the truck was tuned was before I rebuilt the leaking and crappy pattern injectors to pop at the upper end of spec.
This pic is off another thread on MUD. The green circle shows the fuel adjustment screw. Turn it in to turn down the fuel. The big nut is a keeper nut and you have to crack that to turn the screw.


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