JoeH

Look along the flywheel housing from the starter motor, up over the top to about a 2:00 position. Mack dealer couldn't get one, but I found one aftermarket at a warehouse in Allentown PA, picked it up.about an hour after talking to the guy. I think it was about half the price Mack wanted for it.

This was the start to our Thursday... My cousin was driving when this happened. Brand New tires on brand new rims, second day on the truck. Tire tech put on 8.25"rims, but the counter man ordered them to have 9" rims: 7,500 lb rims vs 10,000 lb rims. Fortunately it failed at 5mph not 50... Shop replaced junk tire and both rims with the right rims that afternoon. I had to make a second trip to the shop to get the torch as the rim bent itself around the backside of the brake drum. When we got it back to the shop and got the other wheel off it was already buckling and had flat spots developing on the inside bead. The tire is still on the axle. Apart from a little damage to the bead surface it held up well...

If it's an auto then you probably have cracked flywheel housings.

GIVE THEM YOUR VIN NUMBER, WTF???? Dealer incompetence is ridiculous...

Fed writes laws, and states adopt it to the extent they want. Interstate commerce has to meet certain criteria, but individual states can operate however they want internally. In New York they can run 80,000 on a triaxle, but can't have a lift axle switch in the cab. PA triaxles can't exceed 73,280, state doesn't care where your lift axle switches are. CDLs are pretty much the same. Similar, but a few variations.

Let's be honest, if someone takes the test in an auto, do you really want the behind you coming down a mountain in a manual? Provides they were able to get up the other side first? We bought an auto mr688 last year, and for what the truck does, (volumetric concrete mixer) it's the right transmission for this application. PTO can operate while in gear, so I can creep along and pour concrete at the same time. These same conversations I'm sure were had decades ago when manual transmission cars started going by the wayside in favor of automatics.

You're paying for the 605 hp. That's only about $530 per hp...

A thread chaser might be handy for the end of the trunnion bar. Ours was pretty worn away, but we managed to chase some threads clean enough for the clamp to thread back on.... Remember, the bar hangs from the spring. So put cribbing under the bar before cutting u bolts.

Sorry I was basing it off this conversation from several years ago.

Looks like they start on 44k setups?... Don't know if they make 38k versions. Also I havent seen any weight ratings listed on any of the quick research I just did. So I wouldn't trust it as far as I could throw it. 38k is a bit light weight for off-road dump truck work, but we have a 1979 volumetric concrete mixer truck we have had since 1986. Same 38k rears, the suspension has held up very well. It just got new rear springs a couple years ago, one side was sagging, other side finally broke a leaf. Now that you know what breaks to look for I'd say run it. Also, the trunnion bars do break sometimes. We had one break on our 58k setup between the saddle and the stand.

Top bar and bottom bar on 2003 MR688S. I'd figure it takes any twist out of the frame by creating a "box" support structure. Battery box on one side, fuel on the other, and it's about 2 feet forward of where the splay starts in the frame to go around engine/trans. I think I heard a few years ago that at one point Mack had frames cracking oddly, so they tweaked cab mount design and probably added these frame stiffeners.

My top bar isn't any heavier than the lower bar.

Mildest winter we've had in PA in a long time. Gonna be 85 for the rest of the week here near Philly.

I always figured they help with frame stress where the frame splays out around the engine and trans. My MR688 has 2 of those bars, one below, bolted to a bracket on the rear spring hangers, and a second one that goes across the top above the trans, right behind the engine.

They are rubber/nylon bushing saddles, you can see the tube/bolt sticking out. Look for broken U bolt on the inside of the spring pack, down IN! the saddle holes. Our broken U bolt had rusted thin down inside the hole and thus the break was in there, where you can't see it unless you know to look for it.

The U bolts keep them from fanning out. I suppose you could have a broken U bolt, we did have one of those a couple years ago. But we also had broken springs develop on that same truck. The U bolts keep the springs sandwiched with thousands of pounds of force. The only way the springs could slop around is broken leaves, or stretched/broken U bolts.

I'll let your imagination figure out what happens when all 3 bottom leaves break and the one axle disconnects from the spring pack. Remember the springs "hang" from the axles, so that side will hit the ground.

I'd be jacking that truck up and cutting the u bolts to inspect leaves. After I ordered a new spring pack. And you'll want to do both spring packs at the same time, otherwise one side of the truck will ride higher than the other.

Those leaves probably are broken, the breaks are likely hiding behind the u bolts.

Stock that engine should make 30+ psi of boost. If you were making less than that then I'd suspect boost leak. Our 95 E7-350 had dropped down below 25 psi, so we checked for leaks and found a nice long crack down the weld on the charge-air-cooler.

Did you lube the fuel filter O-rings before putting them on?

What's the history of this truck? Have you owned it long? Did you buy it with this problem? Did the problem start after having the brakes replaced? Joey may be on to something with that frame twist. Looking at it, it would appear the frame is twisted in such a way to apply the least weight to the passenger rear wheels. Typically trucks have ABS on the steer and the front drive axles, not on the rear drive axle. So your ABS would of course do nothing in this situation.

Any chance of swiping the oil pickup off the truck you're getting the pan from? I doubt the pickups are different depending on pan. Only differences I could foresee would be based on sump positioning. The pan and oil pump assembly can be flipped end for end depending on front axle to engine positioning, but I don't recall if there was a "center sump" oil pan.

My first though was compression ring, but that'd have a hard time getting out and dropping down. Looks like it's a bimetal piece, 2 separate colored metals appear to make up the piece.

I wouldn't mess with the filters. Leave it as is.