JoeH

I'd disassemble the entire thing, sandblast and paint each individual component and slap it back together with new bolts.  Rust sets in between every layer and pushes things apart. There will be rust cancer hiding behind suspension brackets.  

2 hours ago, MackE7760 said:

That is the present game plan, pull it and see, but was hopeful that maybe someone on here had “been there, done that” before that could give me tips for potential pitfalls

Read the manual I linked. Looks like trans has to come out, fly wheel has to come off to remove the drive gear/idler gear assembly. More to it than just pulling off the output assembly.

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=7607

Looks like there's a link for View File.  I downloaded it, it's the same manual for e7 and ETech engines, so that covers yours.

All I know is the technical name is REPTO. Rear Engine PTO.  Should be information in a Body Builder manual.  I should think it would be no problem to remove it and the associated gears.  Take it apart and see what you see!

Could be daytime running lights that stay on like modern cars do. You shut the car off, go inside, and the lights shut off after a minute. That's my best guess. This is my first MR too, haven't had much play time with it.

4 hours ago, Hook n ladder 1 said:

Good luck with this project...you did a lot of work so far.  

I'm a big MR fan.  Drove one for Waste Management.  I did want to buy an MR tractor (old USPS rig) and either stretch it and make an RV out of it or put a sleeper cab on it.  I have a CH midrise sleeper that i was going to use but, there isn't enough time in the day.

Sleeper would be interested on an MR, it couldn't mate to the cab as there's part of an engine in the way.  Would definitely be a neat rig if you could pull it off!

New Years Eve had the paint store closed, so we didn't get as much done last Friday as we hoped.  Finally got the right frame rails and about 10-15 miscellaneous brackets sand blasted and painted. Everything is sitting in the garage baking at 75 degrees overnight. 8am tomorrow starts the install process.  Should go smoothly, no reason for it not to.  Lift axle should arrive end of the week, hopefully the shortened driveshaft will be back soon too.  One of my tenants is a collision center, I may ask them to prep the cab for paint.  That's one task I don't enjoy so much. More pictures promised as progress continues!

2 hours ago, Mark T said:

All the work is done on top of the piston ( timing injection pressure , matching of turbo cam and fuel delivery ) and more important than any of it ?

Someone figured out how to do it for a reasonable amount of money .   Think many people realize one of those old constant torque Maxidynes were never anything bigger than what would be called an 11 liter today ? 

I think this hits closer to the mark.  "Lugging" is trying to accelerate when you are too far below your power band.  There is a surging effect in power delivery that damages things.  Mack figured out how to make smooth power at a lower RPM, allowing them to start the power band lower and thus reduce the need for so many gears.  All this achieved by injection timing, fuel delivery, etc.  Mack, having engineering control over every vehicle component from engine to trans to rears allowed them to do what other brands like CAT and Cummins couldn't.  CAT and Cummins had to design their power delivery to match generic transmissions.  Not a chance in hell Eaton would have made a 5-6 speed transmission to pair as an option for one specific CAT motor with a wide power band motor.  Not enough sales market.  Eaton would be dependent on the end user spec'ing a KW or Pete with that motor and trans to sell the transmission.  Mack was able to build a 40+ year reputation on it. I don't know what kind of market share Mack had on OTR long haul trucking from the 60s to 2000, but I'm guessing not too much as truck stops don't seem to favor them.  I'd guess the Maxidyne setup earned them a huge share of local/regional market, where 55-60mph was all that was ever asked of a truck, but left the market open to CAT and Cummins for cross country trucking where the bigger liter engines moved along at 70+ mph.

Type of valves shouldn't matter, the slower an engine turns over the easier it is to keep valve train (pushrods, rockets, lifters, etc.) from floating.

Do t know what Rees valves are.

My understanding is that it is high oil pressure. Most trucks regulate oil pressure around 45 psi, but our 1979 maxidyne runs about 90 psi. The higher your oil pressure the more it can withstand the downward pressures in the crankshaft journals before metal to metal contact. 

Right frame rail has the cab tilt mechanism, and since the right frame rail isn't in the truck right now..... We had to improvise.  Left rail cab hinge is installed, right cab hinge is suspended by strap, and the cab gutter line is suspended from another strap, from beams going from our A frame to our pallet shelving. Redneck ingenuity is heavily at work here...

Left rail is primered painted and installed. Right rail has been removed and separated, tomorrow is hopefully sandblast, primer, paint.

Supply chain issues are a bit screwy. In our hurry to get going we have had to reuse a lot of bolts before sourcing new ones. Last truck we did like this was 10 years ago, and I dont think we had any trouble getting bolts.  

Pictures show left rails laying flat vs right rails still with rust jacking.

An interesting proposition, perhaps a project for down the road.  Budget and time don't allow for it now, truck needs to be in Iowa in February to get the body mounted on.

1 hour ago, 1965 said:

I’m thinking & hoping you will like that automatic 

I think I will too, I've driven automatic oil/propane delivery trucks and they're easy.  What I'm nervous about is off-road capabilities.  We get in people's back yards and find soft ground sometimes.  I need to inspect the automatic power divider.  Full lockers would be sweet but they're hard to come by.  Truck has Automatic Traction Control, piggy backed into the ABS system, which I had hoped was on all 4 drives wheels, but it's only on steer and rear drive axle.  I may buy toner ring hubs for the intermediate axle and steal the steering ABS sensor system for the intermediate axle so I have traction control on 4 drives.

Currently the left frame rail is out & sperated.  So much work just to alleviate less than 1/4 inch of rust jacking.  Monday will be sandblast the frame in the rain. Will tent it with the boom of our crane and a 30x50 tarp, then run it inside the garage for paint. Then crank up the heat and cook the paint!

1 hour ago, 67RModel said:

I assume you mean Erie, PA. I wonder why they would do that considering dual tandem rears running 11R22.5 tires and a drop axle are legal for the gross weight the truck is registered at. My experience with Waste Management is they are crazy budget conscience and always looking for a way to lower operating costs. Capped 11R22.5 drive tires have to be way cheaper than 315s although I have never bought 315 tires.

A 315 is much more forgiving when run with a flat tire next to it, especially with the constant sharp turning.  Also has a lot more ground contact when driving into landfills.

And yes this was a trash truck.

The main question I had on peanuts is whether "full open" was an option, I have to test it again but I think I got it stuck in the yard with only one wheel spinning. I'd love to have full lockers, but people dont spec them enough for there to be any in used parts yards.

2003 MR688S, AI-350, Allison HD4560P, 5.32 rears on 315/80R22.5

Top speed?

Also, I know Mack makes an air operated and an automatic peanut style power divider.  Is there a full open rear tandem setup also?  Picture attached.

For $117 it better change itself!

Buying our first computerized truck, a 2003 MR688 with an AI350.  What do you guys use for diagnostic adapter and software?

I downloaded Diesel Laptop's "Diesel Explorer 2.0".  Should I get their adapter or the NexIQ?  (The current NexIQ skips out on one of the adapter plugs, while the Diesel Link has all of them. )

I plan on doing the "dead dog" backpressure remediation on this truck at some point, cam, exhaust manifold & pipe, etc.

Buying a 2003 MR688 with an AI350 and an Allison auto.  What are my options on engine brakes? Can't find Mack on PacBrake website, an exhaust pipe brake is by far easiest to install.