BACKinMACK

mowerman, did you get that scoop? If so, was it pricey? I know dumb question it is MACK. I have been buying from my local dealer. They deliver free so brings the total price within reason on some things. I have not priced yet from my dealer. Thanks

Got that right. Watched a D O T inspection many years ago. Here in this state they are part of the state police. Enjoyed watching him crawl around under that truck scraping up that automatic pistol without a care. Never know when a crime might pop up while inspecting a lowbed. Of coarse they don't pay for them.

Thanks all, I will keep yall posted.

Jojo, I can't see the o-ring behind the pinion bearing cover or the spur shaft cover. I see one at the cover for the bevel gear compartment. I like the idea of removing the PBC to swap out the seal. At the bench with a beer at my side. But swapping it out in place isn't much of a chore. More of a chance I could knock my beer over. I am working off of an exploded parts view of the carrier from my dealer. I will replace the bolt and straps. Than you for the help Jojo and all others who have chimed in.

Thanks Jojo. I got a new cover. Didn't know about o-ring under seal housing. Will give my mack dealer a ring for that. What is you thoughts on the gear oil? And how much will I lose pulling that seal housing and spur shaft cover? Sorry your not in Maine to enjoy the weather. But it looks like you got your fair share of winter down there. Thanks again

Here is another question for the group. I am third owner, second owner had it about a year and put less than 2000 mi on it. I contacted the original owner about any PM history. looked at me like I was speaking Latin. My guess with 288,000 mi is the carrier lube is original. Don't know what MACK used for oil when built in 1999 but thinking it has plenty of life left. It is a dump truck from birth so very little long haul runs. Runs from pit to project locally. Pulling a tag and site work. It has been loaded heavy by looking at the springs. Changing them will be a project soon. At +- $250 for each carrier oil. In a perfect world I should change out the oil but my wallet is not designed for a perfect world. 44,000 rears Any advise?

Yes I agree it must be steam cleaned. These pics were after I drove it home from seller. About an hour and half drive. The wind must have forced the oil back making me think the leak was at the gasket not the seal.

My first thought was the leak was at the gasket between the pinion carrier and the main housing but came to my senses and figured it had to be the seal. But again what caused the seal to fail?

Here is my leaky seal. Also the side cover is rusted and leaking.

So you think its better to pull the seal only instead of unbolting the seal "retainer"?

I got another question on this seal change. Will a lot of oil be lost?

I am about to do the seal on my also. I have been heatin and beatin most of my life but as I get older I don't like surprises. So I got the puller. Tiger tools are the best but the most expensive. I looked for the best deal for what I do. I maintain my own stuff not a shop. so price was the factor. Found a new CAL-VAN on EBAY model 497 for $267, offered $230, came back at $250. So I took the deal. free shipping. Sure its made in China. My truck has 6 yokes, even if I only change two that aint a bad price to pay for knowing that yoke will come off. I was gonna make one but a 2" annular cutter 1-3/4" steel rod. 2" won't fit u-joint cap space, some 1/2" flat stock and a couple 3/8" drill bits, drill and tap for the threaded rod from my jaw puller adds up fast not to mention time. So anyways the rubber dam your talking about is behind that cup shaped piece behind the yoke? To cut or not cut. That will be the question. My concern is what is causing the seal to fail. Could be dirt behind that rubber which I had never heard of or loose bearing. Only 288,000 mi on 1999 RD688S triaxle dump. Time will tell. When it gets warmer cause I work outside. My advise get the puller. After I bought mine I found one the for $244. buy now. Will send picture of my leak later its on a different computer.

10-4

My truck brake lights come on with the trolley activated. If I remember correctly when I brought the truck home this fall the trolley lever when pulled down slowed the truck(no trailer). Not sure though, I have not driven it since. Doing some repairs for this spring.

Is yours set up for a trailer? Mine is a tri-axle dump truck and it is plumbed for a tag along trailer. It also has the thee valves in the dash. Yellow red and blue.

I did not know that. I thought the trolley activated the tractor rear brakes as well as the trailer brakes. But your saying the trolley only activates the trailer brakes.

Thanks for the information. I do have the trolley lever in my 1999. I did see a line in the schematic that Double clutch posted that went to the trolley also.

You nailed it Double Clutch.

Thank you double clutch.

Hello, I am replacing the treadle valve in my 1999 MACK RD688S dump truck. I believe it is original. The air line fittings are a mix of push to fit and compression. The two larger 1/2" lines are compression, the balance being five 3/8"lines, and one 1/4"line are push to fit. Can I replace the 1/2" compression with 1/2" push to fit? Or is there a reason those are compression? All piping to and from valve are plastic. I just added pictures. Can anyone tell me what the piece is to the left plumbed into the top section. I am guessing a check valve? Maybe a pressure regulator? Thanks in advance for any help.

Thank you for the tips.

Tap, tap, tap.....is this thing on?

Replacing my E6 brake pedal valve. Didn't go with the $45. valve/pedal aftermarket that is available. Brakes are too important. Plus its not in a location that I want to visit twice. So I found a new all Bendix setup that is old inventory open box. Not sure how long it has been on the shelf. Any advise as to whether I should tear it down and lube the o-rings. Or is it built for extended shelf life. Any advise would be welcome. Thanks

Hey Lough, I know its an old post but do you still have those MACK window trims? The color even matches my interior.