Cruise Control - Inclines & High RPM's (1 Viewer)

[JMan5000]

Did some searching and couldn't come up with too much. I've got an 02 LC w/ 160K - stock. So when I'm cruising at highway speeds using cruise control and hit a decent incline the CC makes the tranny drop down to 3rd gear and shoots the RPM's up to about 3500. Only problem is that it revs so high it sounds like I'm going to shoot off into the stratosphere at warp speed - it's surprisingly loud. After I level out it goes back into 4th gear and 2500 RPM's. I'm guessing this is completely normal, but my concern is that I'm heading out to Wyoming in a couple months and I will be going up a lot of steeper grades for a long period of time - keeping the rig in 3rd and 3500 RPM's for several miles probably isn't great for the engine? I can obviously not use CC and not experience the warp speed revving issue, but that's not optimal when driving 17 hours straight. Planning to maintain a speed of about 73 mph for the trip and I'll be pulling a small trailer with 2 quads and loaded coolers. Any advice is greatly appreciated - thanks!

 

[nissanh]

Completely normal. If you are towing, don't go at 73 MPH at any case. IS the fan clutch OEM or AISIN?

 

[ga12r1]

Did some searching and couldn't come up with too much. I've got an 02 LC w/ 160K - stock. So when I'm cruising at highway speeds using cruise control and hit a decent incline the CC makes the tranny drop down to 3rd gear and shoots the RPM's up to about 3500. Only problem is that it revs so high it sounds like I'm going to shoot off into the stratosphere at warp speed - it's surprisingly loud. After I level out it goes back into 4th gear and 2500 RPM's. I'm guessing this is completely normal, but my concern is that I'm heading out to Wyoming in a couple months and I will be going up a lot of steeper grades for a long period of time - keeping the rig in 3rd and 3500 RPM's for several miles probably isn't great for the engine? I can obviously not use CC and not experience the warp speed revving issue, but that's not optimal when driving 17 hours straight. Planning to maintain a speed of about 73 mph for the trip and I'll be pulling a small trailer with 2 quads and loaded coolers. Any advice is greatly appreciated - thanks!

Maybe just slow down a little bit if you dont like turning 3500. I towed a 4K lb trailer from Georgia to Colorado and back with my 2000. I towed in 3rd the entire time at 65mph. That was 3200 rpm in my rig the entire trip. I had no issues and I don’t think 3200-3500 is bad for the engine at all. You should be towing in 3rd with OD off though.

 

[JMan5000]

Completely normal. If you are towing, don't go at 73 MPH at any case. IS the fan clutch OEM or AISIN?

I'll dial down the speed a bit - I know one other guy in our crew is taking out a bigger diesel and planning to go above 70 the entire way...so I was hoping to keep up.

Not sure about the fan clutch branding - what's the difference with having one or the other?

 

[dace voit]

Like said above, OD off when towing is best for your transmission. If your on flat highway and the motor isn’t struggling then OD on is ok. These motors have no problems spinning at 3500 or even 4K rpms(it’ll just eat more fuel) but if under heavy load, easing off the throttle will help keep the engine and transmission temps down. Living in Colorado I drop the transmission into a lower gear and hold the engine at 3k rpms. I don’t look at speed as on some passes I might be in 2nd at 3k going slow when towing.

 

[JMan5000]

Maybe just slow down a little bit if you dont like turning 3500. I towed a 4K lb trailer from Georgia to Colorado and back with my 2000. I towed in 3rd the entire time at 65mph. That was 3200 rpm in my rig the entire trip. I had no issues and I don’t think 3200-3500 is bad for the engine at all. You should be towing in 3rd with OD off though.

I had O/D turned on...oops. Didn't even think about that. O/D is the small button on the shifter - right? Were you using cruise control?

 

[ga12r1]

I had O/D turned on...oops. Didn't even think about that. O/D is the small button on the shifter - right? Were you using cruise control?

Yes, it’s the small button on the shifter. The only time I didn’t use cruise was when I was on high mountain passes in Colorado. It doesn’t take long to get use to cruising at 3200 rpm, it’s really smooth. What’s the speed rating on your trailer tires? I’ve seen so many people have blowouts because they are exceeding the maximum speed of thier tires. The majority of trailer tire failures are because of this. I believe in better safe then sorry when it comes to that.

 

[JMan5000]

Yes, it’s the small button on the shifter. The only time I didn’t use cruise was when I was on high mountain passes in Colorado. It doesn’t take long to get use to cruising at 3200 rpm, it’s really smooth. What’s the speed rating on your trailer tires? I’ve seen so many people have blowouts because they are exceeding the maximum speed of thier tires. The majority of trailer tire failures are because of this. I believe in better safe then sorry when it comes to that.

OK thanks - that's what I though - just had to confirm. Not sure what the speed rating is - they are 10" rims and the tires are new (trailer is at home right now). I haven't towed too many times since I purchased the rig in March, but I usually keep my speed around 70-73 mph. Having it in O/D is no problem when on level ground - as mentioned - but that makes sense to have the O/D off while traveling through areas with altitude changes to save undue stress to the engine and transmission. It's OK to hit the O/D button while moving I'm assuming?

 

[ga12r1]

OK thanks - that's what I though - just had to confirm. Not sure what the speed rating is - they are 10" rims and the tires are new (trailer is at home right now). I haven't towed too many times since I purchased the rig in March, but I usually keep my speed around 70-73 mph. Having it in O/D is no problem when on level ground - as mentioned - but that makes sense to have the O/D off while traveling through areas with altitude changes to save undue stress to the engine and transmission. It's OK to hit the O/D button while moving I'm assuming?

Yes, not a problem at all when moving. I wouldn’t be too surprised if your trailer tires are rated for 55mph max

 

[JMan5000]

Yes, not a problem at all when moving. I wouldn’t be too surprised if your trailer tires are rated for 55mph max

Oh man - I hope they're rated for higher speeds than 55mph. I'll check them out tonight. Thanks for the input - very much appreciated.

 

[dwh13]

We just got back from a 5,000 mile trip out to Colorado and I wondered the same thing - it seemed like I had to floor it to get up the slightest grade. I think the lower air density is really hard on these. Glad to hear it's normal for these trucks.