long pull, one problem

[carco]

Just back from Taylor Park, Colorado, ATV trip. WOW! One problem while pulling Cottonwood Pass 12000', out of Beuna Vista Co. excessive engine and trans heat. Pulled up to last switch back engine temp 230, trans temp 250 @ ambient temp of 82. Pulled over onto last pull over @ last switch back, did not know I was that close to top. Waited 20 minutes and temps still not comeing down, so went onward. Pressed accelerator to floor truck barely moved, could crawl as fast on hands and knees for length of truck and trailer, so clicked #2 level from #1, on Edge attitude and now a little more smoke and finally truck started pulling. 3/4 way down other side about 10 miles before trans temp lowered to 200. When returning back over the pass we did not push as hard and temps stayed @ 200 trans and 210 engine.
Other wise, truck was great! DIC said 11MPG, 54 MPH ave, for 2780 miles, hand figured mileage was lower, 10.59 MPG. Trailer is a 38' gooseneck enclosed. Total gross weight truck and trailer 21040#; FA 4740+ RA 5360# + Trailer 3 axles 10940# on CAT scales. Ran mostly 67-72 MPH. Pulled hill up to Eisenhower Tunnel, I70, from west side @ 50MPH passing most other trucks pulling trailers. Grade brakeing was fantastic!! No overheated brakes, brakes not even used all that much or hard, except when that line of cars appeared through the fog @ a light near Colorado Springs on the trip toward camp, wow, but it stopped! safely. What a truck! bob.......

[sluggerjoe]

I hear ya on the grade engine braking thing. I pull a 28k rated 3 axle gooseneck occasionally, loaded with some things that GM probably wouldn't approve of and I just love that Allison tranny.

11 mpg with that load pretty darned good for a new truck. How many miles are on it?

[byronlj]

carco,
My buddy just came back from taylor and over cottonwood pass. He has an 01 cc w/8.1 gasser. He said his temp just started to rise as he hit the crest pulling a 37'toyhauler loaded. I guess he went up a little faster because he knew the route. It might have given him a little more fresh air by going faster.
Dave

[carco]

Sluggerjoe, 17000+ miles.
byronlj, when I went hard and fast temps rose, when I moved slower temps were fine.
bob.........

[olimaxx]

i did that the first time i towed .use the tow haul mode and your problems will go away.

[Kennedy]

Yes, my question would be were you in T/H going up, and how fast? I don't see the Allison runing hot on either of my trucks typically.

[carco]

John, yes, in tow/haul all the way up & down. Do not remember how fast, just that I was pushing hard on the way up the first time; going to see how the DA would handle the altitude and hard pull!! OK except temps, and then no power to pull away after being hot. Hot enough under hood temps that the power steering oil was hot enough and thin enough to sound like a low fluid condition when steering wheel turned or brakes applied. bob........

[Colorado Kid]

The "No power to pull away" wasn't because you were hot, it was because you were at 12,000 feet and idling. Without boost in the thin air (low Manifold Absolute Pressure) the smoke map won't let it put in any fuel, and without fuel it won't make any power (or exhaust to spin the turbo). Shutting the A/C off helps with the engine heat and response. The granny gear on my 2002 helped me get rolling enought to get rpms up enough to make a little boost . . . low range could do the same for Allison trucks.

The Engine I drove that was worst effected by this was about a 1990 C-series Cummins in a School Bus. The thing was intercooled and pulled fantastic in the mountains . . . I drove it up I-70 from Denver and pulled off in the parking area just after the Eisenhower Tunnel to wait for my partner, whose Detroit 8.2 Turbo had high EGT and Coolant Temp issues which had forced him to slow down. I was all proud of my cool as ice Cummins until I went to back up to get out of my parking space. Full throttle increased in gear RPM from 500 RPM to 550 RPM and nothing else happened . . .seems that mechanically injected Cummins had an "aneroid", a clever little vacuum filled device that limited travel of the fuel plungers to prevent smoke and high EGTs, until boost arrived and the increased manifold pressure moved the linkage. If the truck ahead of me hadn't moved I'd still be sitting there. (Well, I could have called for a tow truck to pull me back a few feet, but it wasn't ever going to move uphill under it's own power.) The 8.2 bus made a cloud of black smoke, but it could back up. At 5,000 feet the Cummins had some turbo lag, and hit hard when the boost came on, but at 11,000 feet it had infinite turbo lag from idle.

[carco]

ColoradoKid, thanks, that sounds like a plausible answer I can buy into. All other things were ok, just no power, like no fuel or little fuel being injected into the cylinders. There was some, though little smoke out exhaust perhaps showing a lack of boost therefor a rich mixture but once rpm was obtained the smoke cleared and power resumed. Never another problem for 2800 miles! Wish could have done better than 10.5 mpg oh well, lot of weight 21000+ and hills. Thanks again, bob................