High RPM's for long periods of time?

dieselenthusiast · **Posted:** Sat Apr 03, 2010 12:57 am

My KJ runs approximately 2000 RPM’s @ 70 MPH in overdrive and 3000 RPM’s @ 70 MPH in drive. My questions is: Is it hard on the motor to leave it in drive @ 3000 RPM’s for long periods of time? Living in the mountains, I just don’t have the power to stay in overdrive at 70 MPH without serious back and forth shifting. I'm currently running the stock tires, but I do have the extra weight of the ARB bumper, winch, all 4 skids, and rock rails.

JL Rockies · **Posted:** Sat Apr 03, 2010 1:16 am

In my past life, I drove 70+ MPH for 15 hrs a day, 3 weeks out of the month all over the rockies...... Now everyone can tell you why it's bad.

SavageUrge · **Posted:** Mon Apr 05, 2010 12:09 pm

Not only will your fuel mileage suffer dramatically, so will the wear and tear on your engine and transmission. I've noticed that keeping the KJ below 2000 RPM's makes a world of difference in mileage. Hopefully your abiding by the severe service guidlines when you're replacing the diff fluids as well.

dieselenthusiast · **Posted:** Mon Apr 05, 2010 12:27 pm

SavageUrge wrote:

Not only will your fuel mileage suffer dramatically, so will the wear and tear on your engine and transmission. I've noticed that keeping the KJ below 2000 RPM's makes a world of difference in mileage. Hopefully your abiding by the severe service guidlines when you're replacing the diff fluids as well.

Keeping the overdrive locked out is much easier on the transmission than letting it shift back and forth. I'll take an oil smaple at 7,000 miles and see what she looks like. I only change my oil once per year (which is about 7,000 miles).

JL Rockies · **Posted:** Mon Apr 05, 2010 3:01 pm

I have 93k miles on the ODO and I get 21 MPG. The speed limit in most places is 75 MPH which is where I lock the cruise in.

dieselenthusiast · **Posted:** Mon Apr 05, 2010 3:07 pm

JL Rockies wrote:

I have 93k miles on the ODO and I get 21 MPG. The speed limit in most places is 75 MPH which is where I lock the cruise in.

21 mpg in pretty dang good for lift, armor, oversized tires, and those speeds. Gotta love a diesel.

Tokyojoe · **Posted:** Tue Apr 06, 2010 2:04 am

5+ years here with the KJ and *KNOCK ON WOOD* I am constantly going in and out of OD and no issues with the KJ yet.

dieselenthusiast · **Posted:** Tue Apr 06, 2010 2:27 am

Tokyojoe wrote:

5+ years here with the KJ and *KNOCK ON WOOD* I am constantly going in and out of OD and no issues with the KJ yet.

That's good to know................. especially with the 42RLE. How many miles do you have on your KJ?

johnb · **Posted:** Fri Apr 09, 2010 4:28 pm

SavageUrge wrote:

Not only will your fuel mileage suffer dramatically, so will the wear and tear on your engine and transmission. I've noticed that keeping the KJ below 2000 RPM's makes a world of difference in mileage. Hopefully your abiding by the severe service guidlines when you're replacing the diff fluids as well.

Gear hunting is way harder on the tranny, fluids, etc than locking in a 3K rpms and staying there. Engine damage? Where's the red line on your tach?

High RPM's for long periods of time?

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