JoeH

It protects the "Control Valve" from "coking."

Book.says it's an oil condensate filter to keep oil out of the system. Depending on Build Date of the engine it may not have had one from factory. I think the pages I sent indicate May 2004 as the change over time frame.

Couple more screenshots from the Book showing some things.

Pages 84&85 for example...

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6148 Here's a link to download (free) the Mack Manual for your engine. Click on "View File" to download. It may have a lot of helpful info for you on this dumb EGR system's plumbing.

A little late to the Party, but the Googleweb is a great friend, sometimes. Punched in "Mack AC400 Engine" on an image search and was met with more than a few choices on pictures of engines minus truck frames in the way...

With that bonnet I keep thinking it looks like a Ford L8000.

Glad we caught it before it dropped a valve or something worse.

Truck is at the dealership getting the go-over and so far with the stumble all they've found is a failing valve rotator, which yielded some small bits in the oil pan and an out of adjustment valve. Cam checks out ok, they don't suspect eup's as there's no knocking sound from the eup "jumping" off the lobe. Cam also looks great from underneath, and they measured the cam lobe heights with dial indicator on the valve stems. They'll put 2 reman cylinder heads on it, plus whatever peripheral junk goes along with that. It's gonna cost an arm and a leg, but I have no doubts regarding their competence, and it's gonna be done a whole lot faster than doing it ourselves. And we need this truck done ASAP.

Long shot but is this camshaft changes file still available? Can't get the link to work.

No the AI ones are good, the AC ones are shit. Sorry bud. The AI ones use a bump on the exhaust lobes to pop exhaust valves open during intake, combined with restrictive exhaust manifold and turbo to create back pressure. That's the EGR system. Pop some pre AI engine parts on there instead and you're done, good to go, and no cop will ever know it's deleted, and no effect on computer software. The AC motor has that external EGR, vgt turbo, extra sensors, different eecu....

Not saying you can't delete Macks, but there is very little aftermarket support for it.

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6543&GroupId=-1 You're looking for Mack manual 8-201, if your dealer is halfway decent they should be able to order it for you, but you can also download it for free by clicking "View File"

My absolute favorite is 23-021 https://macktrucks.vg-emedia.com/ProductListing.aspx?keyword=23-021 It's a data program on a flash drive that has just about every Mack wiring diagram from 2000 forward. Engine wiring, chassis wiring, transmission, vendor engines, emissions wiring... Well worth the $180, though your 1995 won't be in there.

Macks emedia website is chock full of free downloadable manuals as well as buyable paper copies either through website or your dealer.

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6401&GroupId=411

I started an account on PAI website which is great for the parts catalogs, but I assumed I'd be able to order parts online too, but I don't see any function for it. Where/how do you guys buy PAI Mack parts?

https://www.ebay.com/itm/384440040267 buy this and you'll be ahead

Probably the sensors on the diff lock mechanisms.

Do you have much mechanical knowledge/support? You're missing a fair bit of peripheral parts on that engine. If it's a free truck that you have to invest a bit to get running I say go for it, but double check first that you can get a title for it and get it registered and legal for the road. Would be a pain to get the truck running then not be able register it because of paperwork issues.

How many miles are on the truck? This truck should have an AI-350 motor I expect. Don't pick up an AC motor for it, it's a different bag of garbage emissions stuff. The AI motor you can delete the emissions stuff and create a much better breathing engine. Just look up "loggin dog dead dog remediation" on this forum.

Look for cracks around the top of the truck frame at the very front of the dump body. I've seen otherwise perfect used trucks that had cracked frames there. As the frame flexes going down the road the front of the dump box creates a pressure point on the frame.

Allison Autos are usually paired with 350-375 hp motors, much more than that and you'll burn out the clutch packs during shifts. Your rear axle ratio is going to be important for quarry work, in PA quarry roads are STEEP! Not sure where you are. Truck has camelback suspension which is ideal for quarry work in my opinion, assuming it's rated for the loads you'll put on it.

The way I see it, Castle Law applies. Someone breaks into your house, make sure you don't shoot them in the back...

Bridge approaches are sketchy in our truck, never noticed how badly interstate roads drop before you enter/exit bridges, but our truck would throw you pretty hard. Fortunately most of our driving is local non highway.