The Heinz

No problem, I try to help out when I can.

Here, I'll post the pictures of what Impact shows and try to explain a little to help out: This is looking at the truck from the front passenger side. The actual VGT is the turbo, which is OPTION 1. The filter in question is in OPTION B, which I'll show below. It goes to the driver's side of the engine. OPTION 15A is the filter FJH is talking about. It should be identical to the 2006 CXU we have in the shop I used to find this. Mack part number is 25502444, WIX cross is 49458. It's mounted on the engine right next to the oil filters. The afore mentioned truck in our shop has different issues, but me and the foreman noticed when the tech revved the engine after fixing a misfire the turbo made a nice little metal-on-metal noise for a split second, like the turbo isn't getting the proper oil quick enough. Fun stuff!

The original part number should be 37QR5140 according to PartsLinq's supersession chain. Searching that gave me some results. Dixie Truck Center in Lakefield, ON has a listing on truckpartsinventory.com, could maybe call them and see if that's an option. https://truckpartsinventory.com/part-details/85075935/used-1997-mack-rb688s-dash-ass-y-for-sale Northwest Truck in Alberta, Canada could potentially have it too, will need to call them to find out. https://parts.nwtruck.com/part/QR-37QR5140 Those are the best options I could find, even though getting parts from Canada is a royal pain, believe me...

Yea, that's my bad for not looking as closely, sorry. I couldn't find any other good crosses, don't know where to suggest you find the right ones either.

The part numbers don't cross, can only assume they're not interchangeable... Thanks for that link, could be handy in the future.

Same here. I imagine using any other turbo would need some aftermarket tuner to program it, which I have no idea on what to recommend. I don't think the turbo off an AI ASET will work, they have different manifolds and turbo mount gaskets, but I could be wrong.

I am not well versed in old truck parts, but I was able to find some different crosses other than the Euclid kit. Found this TRW brand kit K506B, the size according to mpparts.com is 1.250" x 7.88" I'll attach a screenshot to see if it appears what you're looking for.

Wish I saw this while at work, I won't be back in until next week! Thankfully there's been some very helpful replies already. I'll check this out next week just for kicks.

Here's a simple diagram of the CAC system on a similar truck. Like Joey said, the actual charge air cooler is in front of the radiator. You can look up Youtube videos on how to pressure test a CAC system if you need.

Thanks for that info, might help me in the future.

I was able to get a hold of a spec sheet that had parts going up to 80 PSI, nothing on a 100 PSI version. The 80 PSI option supersedes to 25501698, limited availability in Mack warehouses, but obtainable. No PAI cross that I could find.

I checked to see if we had one, but it's been a really long time since our inventory saw one of these. None of our other stores showed any either, and our "best" electrical tech had nothing helpful to give either. This'll be outside of what I can help with unfortunately...

I know which valve you're talking about, but I can't find the part number for the 100 psi version. All the ones I can find are the 54 +/-7 PSI or lower. I'll see if I find anything, but hopefully someone else can chime in as well.

Gotcha, that's quite a ways from me! Glad you were able to find what you're looking for. Hope you stick around so we can see the end results too!

Now that you mention it, yeah I was half-wrong. We see the faulty diff lock switch on Meritors constantly. Customer lost a few diffs to it too, course that could have been driver error masked for warranty's sake, but I digress. We have seen a couple of diff lock switches faulting on Mack rears, but nowhere near as often (or as violent) as the Meritors. Could be that or wiring issue somewhere, unfortunately all I can do is help you guess!

You could contact DEX Heavy Duty Parts, they tend to have used engines for sale, just don't accidentally buy a core engine unless you want to overhaul it! A shame someone stole the valve covers and head, or else you could piece the engine back together and go from there. Sorry people these days have no shame in putting others in a bind. It isn't my money being spent, but it would be great to see your dad's old truck making you money. If you go the engine swap route, I'd try to find an E7 ETECH, pre ASET, which should fit right in (Experts, please refute my claim if need be!). Though like Bob said, the truck was parked for a reason, and an Allison transmission could be why. They can be a bit expensive to fix, but they certainly are fixable. If you wind up needing any parts and happen to not be too far from me in NC, I'd be happy to help locate smaller engine parts like the turbo, EUP's, etc. I just won't be the best help with used engines, I don't have many resources for that.

The actual diff lock switch can be bad too, we've seen this a couple of times. At least the company's drivers said they didn't leave the diff lock on during interstate driving.

This is why Colt's Single Action Army was called "The Great Equalizer." You can be up against a super jacked dude and his pitbull, but just having a firearm instantly puts the ball in your court. People and dogs don't do well after taking a couple 9mm rounds to the body. It's sickening and ridiculous that these people get protected by the bureaucratic system that is supposed to protect us.

Yeah, it's usually cheaper to outright replace than to repair now. It used to be similar with engines, but we've seen a couple of fleets in our area request in-frames on ETECH or ASET engines, which to my surprise actually ended up being cheaper for them. As for transmissions (that aren't mDrives), we never tear them down with the exception of a few Allisons and one Eaton. Being a dealer, it very much is a Parts Cannon methodology: metal in trans fluid? Quote a reman and be on your merry way. It's always a parts changing job though!

I think they went away from the shim setup, but I could be mistaken, and they certainly fixed the cup issue after the early models of the engine; doesn't mean cups and injectors are flawless, we see a lot of failures there still! We have had quite a few gear train failures in MP7's now that you make me think of it. The MP10 honestly sold really poorly, at least in our area. I've only seen one truck to my knowledge with that engine.

You're absolutely welcome. The DO cover their own workmanship, but I feel like they'll do fine with a manual transmission; all of our failures were with automatics. They've done a good job with the couple of diffs we've used.

They're not lying, no dealers in the system (both US and Canada) show any, and PAI doesn't even list it anymore. I checked all my old part sources and found nothing. Maybe someone here can help, but I don't think I can...

It may be because it was built in Dec of 1985, but there's a high chance the info I have could be wrong, though I'm using Impact and a VIN finder as my sources. Odd that two places could be wrong, but possible.

Interesting, according to the VIN (with the O's replaced with 0's to correct it) it was built with a 350HP E6 4VH... Guess they swapped engines? Or is the VIN incorrect?

MP7 usually has fewer rocker shaft bolts than an MP8 from what I've seen, along with a more complicated EGR setup. The 11 liter also has a weird timing gear setup with one idler gear bolt being a flywheel housing bolt, which is a bigger pain in the rear from what techs tell me. As far as reliability goes, I feel I see more MP7's have major repairs than MP8's, but that very well could be a sample size issue. My last job at a fleet had nothing but 13 liters and we had few major engine issues, while a competitor had 11 liters and were constantly towing them to the dealer. I personally would recommend the MP8, but my opinion only comes from observation as a parts guy. EDIT: I asked one of our best techs about the difference and the MP7 was designed for heavy duty vocational work. We see them a lot in trash trucks, cement mixers, dump trucks, etc. It makes since to me now that I know, the fewer rocker shaft bolts are massive compared to the 12 small ones on the 13 liter. I guess it would depend on what your trucks are going to be used for. If you've had good luck with the MP8's, I'd probably stick with that combo. Just make sure to change the air dryer cartridge reliably and to keep your eyes and ears out for air leaks in the bellhousing. I've also been told keeping the RPM's lower keeps the mDrive from killing itself as much, but I don't think there's really much that can be done to avoid it.