TownsendMack

Greatly appreciated! Traced a ground that was popping headlight fuse...removed wire assuming it was trailer lighting related , and then engine failed to start and not even turn over...bandaides on bandaids to sort out with all the scabbed wires.

No worries, I'll have to trace it out. I was hoping someone might know off the top of their head. Whatever it was for, there is not a trigger to fire the relay coil..it may be shorted, and not important anymore since most of the feeds are bypassed on the one post. It'll just take time to track probelm wires and circuits with the fluke and power probe as they arise.

Thanks for the response. Yes, alot of added and disabled wires...lots of hands messing about. I would like to clean up for some reliability, but was hoping to atleast have the advantage of the terminal designations under the drivers side hood. I guess most likely a drawing would not help much with all the "patches" that have appeared to have been done over its life.

Looking for a wiring schematic on a 1986 RL688LST dumptruck. The wiki link/sticky seems to be dead. A pdf would be much appreciated, if anyone has copies, as I've been sorting through electrical gremlins wire by wire on lighting for a friend. Also, saw this the other day...looking to track down why this solenoid does not have a trigger...? seems to be more of a terminal junction now... Driverside engine bay, inboard of supply terminals. What was original intent for this relay?

Fair enough. Happen to know the socket size for the spindle nut?

Hello, I was hoping to get some insight of what it takes to do a full brake job (S-cam, shoes, drums et,) on a 1986 RL688LST Mack 10 spd - front and rear. Do I need to pull the hub to replace the S-cam on this year truck? Where is a good place to get parts? Axle spindle socket size? Torque specs for spindle nut and axle nuts?

I appreciate the responses, very good info. It seems like it may be best to look for a newer truck - donor or one less of an adventure to drive. I cant get much more info from the guy selling the '75. I was trying to get a door sticker picture atleast. ultimately, using running gear, or engine, from an older donor sounds like it will make the "newer" current truck weaker.

Hello, we're looking at a potential donor truck to maintain parts for a workhorse Mack. The donor is a 1975 Mack dump truck. The main truck is a 1986 RL688LST Mack 10 spd trdl1070, E6 350 engine dump truck. Are the tranny, running gear, engine, etc compatible for swap? Bolt patterns, mounts, etc?

I found a 500 page progear manual online. Any reputable places to source parts?

Thanks. So what in the hi-lo box starts to go? Is it somthing that can be caught and dealt with early after indication? Whats the tricky part to these rebuilds, finding parts? Appreciate the advice.

Hauled 14 tons this afternoon on the highway and started noticing a whine coming from, what I assume, to be the transmission. The truck had trouble going into Hi, and noise was more pronounced in 3rd gear. What are some things to rule out and figure out how much this will cost? Synchro, shift cylinder, solenoids, shift fork, hot oil, differential noise disguised as tranny noise? I feel like it is odd to have issue more prominent in 3rd. Could this be diff noise traveling up drive train? Does this sound like a tranny swap is in order? What does a tranny repair look like for these units? Can these be swapped with an Eaton? Thanks for your knowledge, time, input.

I'll have to look. Truck is offsite today. My assumption is yes, but will veryify the end of the cable when I get a chance. Appreciate the input greatly.

Hard to say, there are a few gremlins to work out. The speedo connection is flush with the block, so I believe it must have sheared/broke durings its life.

Appreciate the responses. I'll take a look at tach situation...should have thought of that. How is it supposed to attach? It looks sheared? Any issue getting dirt in there if left removed? Usually shift with a bit of finesse and the ears anyways...

In front of the fuel pump, passenger side, on base of block, behind radiator fan, is a hole..that spins with engine running...obvious oil weep coming from the area. What goes here? Recently bought Mack truck for a workhorse. Trying to make sure she runs, and continues too.