2005 XL2 Engine Running Temp, RPM and Gear Selection

[jordangaw]

New to the forum, apologies if this has been covered in length, I've been unable to find anyone with this specific issue.

2005 XL2 with a Series 60 Detroit and Allison Transmission is running regularly just shy of 210 for the engine temp.
I've been told the fan kicks into high at 210, this seems to be happening.
I've had both my high and low relay's checked and the fan is running both low and high.

While pulling hills, I'm forced to downshift manually to get the RPMS up to 18/19K, this could be as low as 3rd gear at times.
Today while running in very hot temps 109 from Barstow to Kingman, I was stuck mostly in 3rd gear running around 50 mph on a minor grade just to keep the RPMs up to cool the engine enough to not hit the 230 mark and red warning lamp.

This became a major issue when I would hit the big climbs and at one point was as low as 1st get barely making the grade.

What's going on here? The fan clutch is new, the belts feel tight, the relay's work, the fan works. Why am I doing wrong or what I am not doing?

Any and help is greatly appreciated.

[twslp]

I see a grade I hit the mode button for performance and mash the throttle. let the ecm do most of the thinking. I have done that run thousand times in different pushers without any issues. just watch the gauges. and warning lights. safe travels. unless your turbo or air intake restricted. dirty radiator maybe.

[Djhinds]

I had a talk with an experienced long haul trucker and he told me on long grades to downshift to the gear that you can hold 1800 RPM at part throttle. You will get better mileage and run cooler.

Safe travels
Dave

[truxton]

Your era bus had a run on Charge air coolers that leaked pre-mature. You should be able to run across there in 5th gear at 1800 rpm and downshift to 4th if needed, 3rd gear should not be needed unless your towing 15k lbs.
Check the simple stuff but I would bet your sucking air somewhere, could be a slight tear in a turbo hose and doesn't reveal itself until extreme conditions. Also do the soap test on the CAC. Yours will either be next to the radiator or stacked on the front of the radiator. Take a spray bottle with a little soap and spray it around the edges where the welds are with the engine at idle, if you see bubbles your leaking.

That's a couple of things you can check.

Later
bv

[jordangaw]

Appreciated! Thank you all for your replies!

[Fratto]

Let us know what you find out. When you say "regularly just shy of 210" I assume that this includes running at speed on flat ground. If that is so, then it seems high compared to the two buses that I have owned (both 1998). If I recall right, the low speed fan is set around 204. Both of my buses would run in the 190's and occasionally bring on the low fan.

If there were no steep grades and outside air temps were reasonable, with the dash AC on and the engine fan in high speed, the engine temp would be high 180s to low 190s with the t-stat appearing to be controlling temperature due to the over cooling effect of the high speed fan.

[Hoffman]

Jordan,
Are you sure you're not getting the engine temp and trans temp confused? My powertrain is the same generation and my trans temp does run at 204-210 regularly, even when not hot outside. I've learned (from reliable sources) that that's simply it's normal range. But the engine runs much less and when at 200+, i consider that too warm for the engine coolant.

The dashboard gauge on the left is the engine temp.
The DDEC digital display under the "Gauge Mode" menu has a trans temp, which is indicated by a circle with gears coming out of it with a fluid graphic in the center. The spikes around the circle indicate the transmission.

But either way, I also suggest cleaning out your radiator(s) with strong stream of water and a soap mixture. Be careful about any brushes, just use a strong stream of soapy water.

Let us know your results.

[Prevosthonda]

Definitely use the mode button and watch boost pressures before and during the hills, I find sometimes even in mode the rpm’s and boost get to low for my liking and as you probably already know, once you loose the sweet spot on a hill you probably won’t get it back and will be with the truckers flashing hazards and crawling . You may certainly have a boost leak somewhere, charge air cooler, turbo boot, charge air pipe rubbed thru somewhere ect. If your boost is not pegged going up hills or under heavy throttle then dig into it. My bus runs anywhere from 195 to just below 210 , but never over that . Same 05 chassis . If things are the way they should be you’ll be able to climb right past most trucks and not go much lower than 4th gear. Again there’s definitely a sweet spot for hill climbing . Good luck


Logan Tidd
06 marathon xl2

[ELucast]

Definitely use the mode button and watch boost pressures before and during the hills, I find sometimes even in mode the rpm’s and boost get to low for my liking and as you probably already know, once you loose the sweet spot on a hill you probably won’t get it back and will be with the truckers flashing hazards and crawling . You may certainly have a boost leak somewhere, charge air cooler, turbo boot, charge air pipe rubbed thru somewhere ect. If your boost is not pegged going up hills or under heavy throttle then dig into it. My bus runs anywhere from 195 to just below 210 , but never over that . Same 05 chassis . If things are the way they should be you’ll be able to climb right past most trucks and not go much lower than 4th gear. Again there’s definitely a sweet spot for hill climbing . Good luck


Logan Tidd
06 marathon xl2

Having driven somewhere north of 2.3 million miles in a tractor trailer back when a 350 HP motor was a big motor and air conditioning was nothing more than a wish, climbing hills in the low 20's MPH when it was 100+ degrees in the shade if there was any and it took hours to get up a big hill. I have to smile at your comment.

[PrevostNewbie]

New to the forum, apologies if this has been covered in length, I've been unable to find anyone with this specific issue.

2005 XL2 with a Series 60 Detroit and Allison Transmission is running regularly just shy of 210 for the engine temp.
I've been told the fan kicks into high at 210, this seems to be happening.
I've had both my high and low relay's checked and the fan is running both low and high.

While pulling hills, I'm forced to downshift manually to get the RPMS up to 18/19K, this could be as low as 3rd gear at times.
Today while running in very hot temps 109 from Barstow to Kingman, I was stuck mostly in 3rd gear running around 50 mph on a minor grade just to keep the RPMs up to cool the engine enough to not hit the 230 mark and red warning lamp.

This became a major issue when I would hit the big climbs and at one point was as low as 1st get barely making the grade.

What's going on here? The fan clutch is new, the belts feel tight, the relay's work, the fan works. Why am I doing wrong or what I am not doing?

Any and help is greatly appreciated.

Jordan, you might already know this but take it slow and keep the RPM's up. The way I drive my bus is I run about 1/2 throttle, and keep downshifting if the RPM's drop below 1700. I think i had to drop to first gear maybe once in my last trip thru the Utah Mountains where we had 12 and 14% grades, Usually i am climbing in second gear and the engine is about 210 degrees. I have like 5K miles on my bus and I am still learning how to drive it, i think we all can learn from the experience of how these machines move down the road, there is no bus that will allow you to keep the pedal mashed to the floor without downshifting and being cautious in 100 degrees plus temps climbing grades. If they say they can they are 1) lying or 2) showing off.