JoeH

Apart from the monster steering gearbox it doesn't look any different from my DM686. What are the axle ratings on a dm800?

Does the dm800 frame splay out to fit around the engine and trans? They can't do the splay, only straight rails, but they can do varying depths.

(on suction side, between tank and lift pump)

Internally collapsing fuel line?

You're supposed to have 2 hands on the wheel for a reason. Buy good tires for the steer. Most blowouts give an indication you'll see during a pre-trip. Bubbles on the sidewalk or even the tread (sometimes the tread will be humped up subtly, this will result in the tread coming off sooner or later) you'll see dry rot splits sometimes on the sidewall near the rim, etc. A thorough tire check will tell you a tire is ready to blow, so when you see abnormalities on a tire just change it. I've caught half a dozen drive tires on my triaxle the past couple years by spotting the above defects. Much easier for me to take 20 minutes and swap 2 drives when I choose to rather than when a blowout decides to choose. Never had a steer go, and hope I never do. But that's what the hand brake is for, operate the rear brakes like a parachute to help stay in line until you get it under control.

USA tractor I owned had 3 park brake knobs, one would supply are to the trailer, one worked tractor parking brake, third worked trailer parking brake.

Knobs are for operating the spring parking brake. The levers would operate either the trailer service brakes or the tractor service brakes (rear axles only, not steering). These levers are to help maintain control of the vehicle incase of emergency situations such as jack knifing.

It'd be an inversion valve on the intake manifold and a slave cylinder on the front of the fuel pump, but at 2001 they're completely electronic so you don't have a puff limiter.

With turbo you would likely have oily intake pipes between turbo and intake manifold.

Sounds like u have wiring issues. Light wiring could be bleeding into malfunction circuits. Turn one light switch on at a time to see which switch circuit is causing the problem. (I'm assuming CH's have multiple light switches)

That'll be shock absorbers most likely. Cab ones, as well as probably the axle shocks. Worth it to just replace all to save your back. Also check your tire pressures up front, make sure they're the same.

It certainly won't hurt; describe what's "rough" about how the granite rides. Knowing how it feels tells us a lot. I had the dad of a guy I drove for take the front axle shock absorbers off my truck one night without telling me. After my back was killing me the next day I went into the office (and he was there eating his lunch) I made it pretty clear to leave the old shocks on until he has new ones to put on instead. IDK wtf he was thinking but I was a little pissed. Without shock absorbers, springs will continue to bounce for a while after one bump.

You should always tackle audible air leaks as soon as you notice them. An air leak can become serious enough that you lose your ability to regenerate air for your brakes. Last thing you need is to kill someone because you couldn't stop your truck. A 73,000 lb triaxle vs a 3500 lb car is no joke.

You should find where the air leak is. My '95 Mack cab airbags hold air for days.

I'm clueless, but someone once told me peterbilt triaxles are typically set up that when you set the parking brake the lift axle comes up? No idea if that's true/common setup or not. No Mack I ever drove did that.

Multiple cylinders = more weight. For dumping/driving on a sideways incline on an air ride truck, I've wondered about having the air bags being able to be dumped on one side or the other to give it a bias towards staying level.

Where will tilt sensors mount? Ever dump a load with worn out hinges and the load is stuck up in one corner while you're on a sideways incline?

Pretty sure it's the turbo you hear whistling, not the tip turbine. Tip turbines don't really spin all that fast I don't think. Not fast enough to make noise at least. Most Mack turbos have a nice whistle to them, let's you know it's alive and well! Don't know if this is a new to you truck or one you've had a while now with a new symptom.

If it's transmission oil it'd probably smell like sulfur/rotten eggs.

Firing orders are generally stamped cast into the block somewhere.

Must have a pretty large air compressor on there to keep up with all those brakes.i wonder how much those loads weigh, and what motors are in them.

Rear main seal would make the inside of the bell housing wet and oily. If that's dry then it shouldn't be the rear main seal. Could be oil pan. How substantial of a leak is it that you can tell it's leaking only when turned off?

Good truck there, Bruce!

It's also very common on dump truck applications for the trolley brake to operate all truck brakes except steering axle. That's how our triaxles are.

Recent problem or did you just aquire it and you're trying to figure out what's going on? How's your tractor protection valve? Do you have your lines hooked up right to the trailer? One is a supply line to the trailer air tanks, the other is a signal line. Sometimes trailers/trucks get the fittings switched up because an idiot worked on it.