JoeH

Unsure how familiar you are with trucks but I'm gonna guess not. You don't shift it like a car/pickup, this is a Constant Mesh transmission. You "double clutch" or dont use the clutch at all for shifting. There's no Synchronizers to match gears for you, you have to do that yourself with the accelerator pedal with foot off the clutch while coasting between gears. Also there is a "clutch brake" that stops the trans from spinning when you push the clutch pedal ALL the way to the floor. These break, get abused and worn out, and are easy to replace once you're familiar with them. There's a step by step process to adjust the clutch and clutch brake, so while what you did got you home, it wasn't the right way to adjust the clutch. The clutch itself gets adjusted by a bolt head on the clutch itself that's accessed through the window on the underside of the bell housing. Clutch brake gets adjusted through clutch linkage. One has to be done before the other, I forget which. Done properly your clutch pedal should have 2 inches of Freeplay before you feel the clutch springs start to resist pedal travel, and the clutch brake should engage on the last half inch of pedal travel before the it bottoms out to the floor. Take note, the clutch pedal should only ever be pushed to engage the clutch brake when the truck is stopped and at an idle. When "double clutching " you are only punching the clutch to about an inch or two into the clutch spring resistance zone. You are not punching it all the way to the floor.

Ant really speak about that particular machine, but I bought a used backhoe this year and it's kinda jerky when the boom is most of the way up. Basically comes down to "how many inches of piston travel" = "how many degrees of boom angle change". The higher up the boom goes the more the boom moves per inch of piston travel. Mine tends to work pretty smooth when I'm using 2 functions at the same time. Helps to split the hydraulic GPM flow to slow down the sensitivity. I also run it at maybe 30% throttle?

No pictures no help! (Kidding... but seriously...)

Start with checking the engine software level at the dealer, the "12b" update should correct much of your issues. If not then give this a thorough read.... https://www.bigmacktrucks.com/topic/50251-mack-ai460-ai427-ami-low-torque-low-horsepower-poor-fuel-mileage-granite-dead-dog-remediation/

The E7 was made with a 460hp option, so there's no reason you shouldn't be able to hit 400+, just need the pros to chime in with what your 350 needs to turn it up.

Wow that's some carnage. I'd say you need a head. Here's a piston from my '79 R686 that dropped a valve seat. Bits of the seat are embedded in the piston.

How many hours are on the motor? Any clue? I think you're headed in the right direction trying to take care of the leaky injector lines. I'd start there before pulling injectors, but my maintenance history relies heavily on how durable Mack trucks are.

Simple til you have to change driveshaft length etc.

My napkin math says you need to be around 3.84:1 rear to hit 60mph. That would be your easiest way to get highway speed.

If you can't get exhaust manifold nuts off, just split them with a hammer and sharp chisel. The water & intake manifold bolts require some tight access to get into, and I believe the intercooler box lid has to come off to get to some bolts on the inside.

My first "tear in" on an engine was the same motor you have there, same year and all. Our '79 broke a valve seat and it dropped into the top of the piston, ruining the head and piston. Similar business size, it's just my dad and I plus my cousin seasonally, so I can relate. Get the head off and see what's really broke. Many of us have the books with torque sequences and settings, so we'll post info for you as needed. Remember though, DONT SET THE HEAD DOWN ON THE INJECTOR NOZZLES!

My strategy is typically remove valve covers and oil pan to get eyes on all the internals. There is a fair amount of manifold work on this particular engine to get the head ready to come off, but it's gotta be done, whether he needs a valve or a head. I'd have that head off right away too, but I think RS is working through a mechanic, so there may be a DIY factor missing.

Time to see what's really broken and pull the head. Also pull the oil pan to get a look at the camshaft and lifters. The carbide faces on these like to break and shave the cam lobes down.

I'd bet your head is fine, and piston may have a tiny dent in it that needs to be deburred. When you take the head off, DONT set it down right side up, you will crush the injector nozzles! You will probably just need the one valve, maybe the guide, and maybe a valve seat?

https://inlandtrucksandmachinery.com.au/product/2005-mack-granite/ Here you go...

Sounds like a bent valve then. If you're lucky you just need a valve, don't need a head.

I quit riding a) because I've got little kids now,and b) driving trucks all day I have a great view of everyone else on the road. Everyone is texting. Grandma, grandpa, kids, etc. I always tell motorcyclists and people interested in getting into riding that if anything happens, regardless of whose fault: it's the motorcyclists fault. Because the motorcyclist is always the one who loses.

Funny thing is... they gotta burn coal to make up for the extra electric demand EVs put on the system. 🤣

Just finished reading, looks like you don't need to do anything.

Pull the Tappet cover off the side of the block. When the 2 forward most pushrods are "relaxed" then you're on #1 TDC starting combustion stroke.

Our '79 has a weak valve spring on one of the heads, the spacer disk on top of the valve stem for the jake brake kept popping out, resulting in excess valve lash.

Probably just a bent pushrod from valve float.

Probably was a quick fix otherwise he might be back asking for other solutions.

If it does have a thermostat then it could be stuck open too. I forget how this thermostat is shaped, I had one that a chunk of the rubber seal around it had failed. Engine almost never got up to temp, and cooled back down quickly if it wasn't kept working hard.

If the truck is empty and not working hard then chances are it's right. 85 degrees outside is waaaaay cooler than the 180 degrees the engine thermostat should be functioning at. It is possible you don't have a thermostat installed, allowing unrestricted coolant flow. This paired with a fixed radiator fan (no fluid clutch) and you'd have to work very hard to heat that engine up. Only way to check to see if there's a thermostat installed is to pull the upper radiator hose off the engine and look in.