Stock '99 Suburban at Altitude

[HammerWerf]

Does anyone have experience of driving a stock 99 Suburban at high altitudes pulling a trailer???

Our vacation plans take us though Flagstaff, Az at an altitdue of about 7,000 ft. Trailer we'll be pulling will be in the 6,500-7000 lb range. I am interested in how well the power held up, overheating and any other stories that are worth retelling.

Trying to decide if the whole exhaust system should be replaced by a 3.5 inch (currently mine is 2.75 inch). The crossover pipe and downpipe will be replaced by the trip this july.

Thanks for the help.

HammerWerf

Thanks for the help

[tanker]

Well I pulled "powder River Pass" at 9666ft elevation on highway 16 East of Buffalo WY in 1998 with my almost stock then 95 6.5TD Suburban pulling a 30' Jayco travel trailer, with 4 adults on board, GCW was 14,000lbs. No problem to speak of, just watched my pyrometer and temp gauge. If you don't have gauges, install them so you don't get the egt's to high. You should be fine. Don't try and race someone, or a big truck. It may take you a little longer to crest the hills but you'll be fine. Do what ever you can to make it breathe easier, exhaust, airfilter, etc. And don't forget a pyrometer and boost gauge. Check all your hoses and belts, and carry a spare belt (your old one ;) ) I always carry some hand tools, and extra fluids in my kit, just in case. Enjoy the ride. smile.gif

[Cooperrw]

I go to Flag often and haven't noticed any power loss yet. On a recent hunting trip to the north rim I estimate my gross wieght was about 15K and I had no problem. Take your time and enjoy the country. :cool:

[rjschoolcraft]

This thread (Significant improvement in towing performance! (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=005059)) has quite a bit of my experience in it. While still completely stock, I towed over Beartooth Pass in Wyoming on US-212 at 10947 ft. in 2000. That is a two lane road with slow posted speed limits and I had no real problems with it. Have no idea about boost levels or egt, because I didn't have gages yet (this was our first trip in the Suburban). I had real trouble when climbing the Big Horn Mountains in Wyoming on Alt US-14 on the way back, though. Had to stop several times due to overheating. I weighed the rig on the way home on that trip and it weighed 16,300+ lb.

Last summer, before installing the intercooler and fan clutch, I had repeated overheating problems in Colorado, Utah, Nevada and California. I-15 through the Mojave desert is no picnic in June at 100+F ambient temperatures. I couldn't run the A/C in many places and even used both heaters to try and help reject heat.

Your 99 should be much better off than my 95 in stock trim. However, I would install and monitor an egt gage (as Tanker suggested) closely. Also, be prepared to slow down some if the engine coolant temp starts to climb.

If you want to avoid all of that, I would suggest the intercooler, exhaust and boost controls from Kennedy. With those mods, you should have zero problems.

[DBlake]

My only caution is that there are two significant grades from Kingman to Flagstaff heading east. The interstate speed limit is 75 which I have heard may be going up to 80. You can make it up the grade but not at 75 or 80, more like 45 or 50. If you TRY to maintain 75, you will be looking for a new engine. As previous posts have noted - install an EGT and watch it and your engine temp. The EGT will give you an immediated reading on heat produced, the engine coolent temp will give you an idea of total heat load and your engine's ability to deal with it. I would also suggest a transmission temp guage as high RPM, heavy engine load, and low over the ground speed will tend to unlock your torque converter. This can quickly overheat a transmission. I installed the TorqueLocker to deal with this. It allows me to obtain torque lock in 2nd gear (or any gear above about 30 mph). Your exhaust mod is a good start. But IHMO, I would also put in an EGT at a minimum. Have fun!

[Cooperrw]

I will agree with DBlake about the two grades but would like to point out that it is an up hill climb from the time you cross the Colorado River all the way to Flag, and that Holy Mosses Hill in Kingman is a short but steep grade also. The speed limit has not gone up yet but there is still some talk of that happening, don't worry about being run over on the steep grades, the truckers can't pull them any faster than we can and they have been widened to three lanes. :cool: