Towing ability of 2004 Suburban 5.3L, 4.10, 4WD

IIRC 7% is the steepest an interstate can be, and still get federal funding. ALtho for short sections, 8% is permited. Generally speaking, they seem to try to keep them to less than 6%.

I've never had issues with interstates.....local roads, like Queen Anne ave going north of FLorentia.....nice little 24% road to drop off or try to go up! Garfield on the east side has a block that is over 20% also. Those little short jaunts can kill you. OR the client that had a 33% grade driveway for 100 yds or so. You could get down it to the house, but not always BACK UP to the road. Of course, you could put a barge up to the dock, drive the rig on the barge, they could let you off at the nearest boat ramps some 4 miles away.........

Marty

I40 between Knoxville and Nashville has the steepest grade in Tennessee it's a 7% grade and it's pretty brutal.

Our 350 was in a 2000 Express 3500 Van and it's problem happened on a short but steep grade about 15 miles from the base of Monteagle close to Nick-A-Jack lake. I really liked driving that van.

Thanks!

Jeremiah

Doesn't look any worse than that grade on I-40 heading West out of Asheville, NC up into the Smokies....one of the few times the big block has needed 2nd gear with the 8500 lb trailer behind it. Might have to put that on the vacation list next time we head south!

I added an edit note to my last post as Jeremiah was adding his post. Thanks Jeremiah for posting the video link.

The summit is the hardest on vehicles. What makes it particularly daunting is that it is peaking around a curve plus there is nearly a blind rest area exit. It's not too bad during a clear day but on a foggy night (common there) it can be treacherous especially when people realize they need the rest area at the last minute.

Iirc the grades are 4-6%

Thanks

Jeremiah

Marty, I'm not sure of that bad grade at Monteagle. Jeremiah said he lives pretty close to there so maybe he'll know. There are yellow grade signs going down that grade but I can't remember what the grade is. For years I've shifted from OD down to 3rd to go down the hill watching rpm's but letting the engine help to throttle speed back. And going up, I've crossed that mountain several times pulling campers and I do just as you suggested. I think about that day a bunch, and I still think I didn't over rev. And that bad hill is at the summit going west-east, and it isn't very long, but it is very steep. There are somewhere around two miles of more gentle grade before hitting the monstor summit hill so the motor and trans are pretty hot by the time we get to the last/bad one.

And thanks for the info on flushing or replacing external lines/coolers. I'll have to make certain that happens.
MartyW

Edit: I just watched the video that Jeremiah pointed out and I don't think the video does justice to the steepness of that bad west-east summit hill. On the video the west-east crossing begins at 47 seconds into the video going up the sligher grades for a few miles, and then the bad/steep summit hill is reached at 1:34 and the top of the summit is reached at 2:00. It's that west-east summit hill where I lost my engine. Jeremiah is this where you lost yours or somewhere else on the mountain?

Jerimiah,

Not a bad pass. I am sure it is worst than it looks per say, but nothing I would go gaga over and not drive up it in a correctly loaded powered rig.

Marty

blt2ski wrote:
How big or bad is Monteagle pass? Can not be too much worst than some here in the NW I have done. ie 5-8% for 5-10 miles or so! Just shift down to a gear the motor does not get thrashed and pushed with the throttle at about 3/4, away you go at whatever speed that is.

ANyway, from some bad experience after one rebuild. I have found it best to flush or replace the rad and any external coolers during some rebuilds depending upon the what or why. Otherwise, the contaminants in the engine are more than likely in the rad/oil cooler lines and cause issues with a new motor at 2-3000 miles......not fun!

Marty

here is a video that gives some idea... its not nearly as long as some of the grades out west... but it makes up for it in adrenaline....

Video

Jeremiah, I find myself thinking about that day a lot. I had the burb geared down locked in 2nd pulling the camper up that brutal west-east grade. I always keep an eye on the tach but that day I had to get around the big rigs with their flashers on and my eyes were off the tach for a few seconds. From the sound of the engine (that I was very used to after several years of owing it) I don't think I ever got over 4K rpm, but maybe that was enough. When we first acquired that burb there was a leak from the rear of the intake. When the engine blew years later my Chevy tech friend remembered that intake leak and he said that if any coolant got into the crankcase from that intake leak that the bearings could have been compromized by that leak and the final trip up hill could possibly have spun the bearing due to load plus damaged bearings. He said he had seen damaged bearings from coolant leaks before.

BurbMan, thanks for the explanation and info. My 5.7 with the hd towing pkg does send the oil through the radiator. I hadn't planned on replacing that. It has been flushed well by the Chevy dealer. I think we've already replaced the radiator but not positive at the moment. If not I guess radiator and external oil cooler will need to go (carringb did mention scope creep didn't he). I think I'll call the local dealer and ask about GM crate motor issues if they didn't install it.

Thanks to all,
MartyW

How big or bad is Monteagle pass? Can not be too much worst than some here in the NW I have done. ie 5-8% for 5-10 miles or so! Just shift down to a gear the motor does not get thrashed and pushed with the throttle at about 3/4, away you go at whatever speed that is.

ANyway, from some bad experience after one rebuild. I have found it best to flush or replace the rad and any external coolers during some rebuilds depending upon the what or why. Otherwise, the contaminants in the engine are more than likely in the rad/oil cooler lines and cause issues with a new motor at 2-3000 miles......not fun!

Marty