JoeH

We have a retired 1980 dm686sx. Has 2 rails, each is 3/8ths. That's 3/4" of rail on each side.

@Ricky Beals if that's a true Heavy Single then you need to buy that truck. Take a tape measure with you and measure frame depth top to bottom and also measure how thick the steel is that's used for the frame. Post them here and we can tell you whether it's heavy or not. I think a standard double frame is a 1/4" rail and a 3/16ths rail, with a 10-11" overall frame depth. A "heavy single" rail should be minimum 3/8" thick I think.

We're all talking from different states. Fed govt drafts laws and states adopt them by and large but they'll adapt/modify as they see fit for their own purposes. Every state has their own nuances for licenses. In PA we get a notice every 2 years that if we don't submit a medical card before the old ones expiration date then our CDL endorsement will be dropped. Doesn't matter if you were "grandfathered" in, my dad got his CDL in the early 70s. He still has to get his medical card renewed I think every year because he's on blood pressure meds. Federal government regulates intERstate commerce, not intrastate commerce. They set the rules for going between states, but have no business telling states how to handle stuff in their own state.

We have one we use every day. PTO takes off the main box, works in gears 1-5, with the directional in Neutral. That's with a side mounted pto. We bought a 1988 Mack with a 7 speed single stick, has the PTO on the rear of one of the counter shafts. Trans needs to be in neutral for that one.

Not in PA; gotta have medical card to keep your CDL. However, you can get an exemption from penndot that states you aren't currently employed to do CDL work, and thus you keep your CDL but can't drive trucks til you get your medical card. How hobby trucks play in... Not sure.

On mine, the ambient air temp sensor is on the driver side in the grill, near where the trans "clean power" wires go into the harness. Your VSS should clear up when you figure out what's going on with your speedometer....

Easy enough to call the dealer and ask, my bet is in the $2500+ range. But... The years you'll get out of it...

Any change in what codes are present?

The E7's had oil pressure issues to the Jakes, there was an external oil line kit to resolve this. But by 2003 you don't have an E7 you have either an ETECH or an ASET AI/AC.

I think you indicated this truck was put together from 3 trucks? If so, maybe the transmission came out of an LE with secondary controls? Secondary control feature could be turned "on" in one of the computers? Just a guess. You could have wires plugged into the wrong sensors. Going off my memory from having just played with my transmission last week there are 3 sensors along the pass side in one harness and a 4th plug coming off the Mack harness going down to one of the trans oil cooler lines below the tail shaft. The 3 plug harness gets plugged in "rear to front" meaning the very last plug on the harness goes in the front most sensor, then the other 2 I think come out of close to the same spot on the harness but one is longer than the other. The longer of those 2 goes to the middle sensor and the shortest pigtail goes to the rearmost sensor. Beyond that all I can guess is the trans needs to get rebuilt? Really don't think I know much more than this ...

Truck got to Iowa 2 days ago, parents are on vacation now, visiting family. Mixer might be ahead of schedule, could be done in 2-3 weeks potentially.

Your gauge died?

I think this is where you post a link to the Mack eMedia book for this engine and say "follow the procedure in here to the T!"

Quick Google search comes up with way more than 4 gallons. Closer to 9 gallons. Remember, the trans fluid does a ton of work, it's not just lubrication. It's the hydraulic oil for shifting gears, operating the torque converter, etc. Builds a ton of heat and takes a lot of abuse.

Secondary shift selector would be for an LE688 with secondary controls in the passenger side. (Steering wheel, brake & accelerator pedal, secondary shifter pad...)

I think it takes like 42 quarts, probably including torque converter. Oil level should be high on the dipstick, normally you check trans levels when they're warmed up and running.

Usually states have a "drive home" permit that goes with the sale. Gives you a grace period to drive it back to your base of operations. Assuming it's drivable...

I know that feeling. But I've grown to like our mr688 because when you lift that center dash panel it's ALL there! Wide open, no skinny access panels in the dash like R models have. If you can't lift the center dash panel out due to the trash truck controls well... Yeah that would be awful. Especially because the factory wiring is buried below crappy wiring for the trash body.

Gotta love jerks!

Granites are nice but they force you into the ASET AI series engines, which are better than the AC engines, but require a few modifications to liven them up. ETECH camshaft and exhaust manifold, turbo (I think) and exhaust pipe that doesnt size down right off the turbo. The AI engine eats some of its own exhaust through back pressure created by the above restriction points. The camshaft has a bump on the exhaust lobe to tap the exhaust valves open a little during intake stroke. Will run ok with all the garbage on there but supposedly they wake up when you update those parts.

I test drove a granite once. Nicest Mack I ever drove, hopped in and it felt like I'd been driving that truck for 10 years. Everything was where it was supposed to be and forward visibility was good. Cab is huge, but I'm used to R models. The granite you listed there is a state truck with plow setup. Looks like it had the passenger side wing plow as well. If that were a northern truck it'd be junk from salt with a bloated 40k price tag. Look it over, but I wouldn't waste much time on it.

Check out baskin truck sales in Covington, Tennessee. They seem to have a decent amount of stuff listed on Truck Paper. Might be worth poking your head around there.

The truck we bought was part of a lot of 60 trucks, all Macks.

Kenworth dealer near me deals in used trucks too. They'll take a whole lot of older trade ins from large construction companies/fleets in the area. Tons of the trucks are in horrible shape but there are a few gems. We bought one about 3-4 years ago. Plow truck, had the hydraulics and everything still. Brand new double frame, probably 5 years old or newer. Engine fires up like it came off the assembly line yesterday. It's a 1988. Even the hood looks new. Probably a million or more miles on the truck, but there's no way to know. There are good trucks out there, you just need to go look at a dealer with a whole lot of trucks. Keep an open mind!

Reading through this has been helpful, our MR688 has this same leak, wondering if it's a cracked housing or loose bolts. Driving the intermediate axle up on blocks should make access a lot easier? Should lift the frame up away from the rear drive axle. Won't be able to look into this til I drive the truck back from Iowa in 6 weeks though.