slingblade

i drove a granite that did it too,never figured it out

3/12 lbs

the jap trucks use exhaust pipe brakes,work pretty good

have you considered putting an exhaust brake on it?i found a good source for info on the jacobs site on how to diagnose and adj their brake assys if it helps,,

thats a good pulling motor,the ones ive drove i had turned up a bit to give more power,not much different than the 460,

weird how dirt is getting in?but it sounds like the compressor is bad,id check the air filter system to make sure its sealed good after the filter element

the most important thing is good drivers though,,

the RD is the best for dumptruckin,,extra springs on front,pull hooks front/rear,hypoid gears in the difs and relatively trouble free electrical system

also check richie brothers auctions,they have alot of older macks from time to time,also look at truckpaper.com,,thousands of trucks listed

check all grounds to motor/chassis and batt

theres an rd diagram on here on pg 5 in the wiki section,im using it to sort out issues with an RW713 i just bought

there should be something on youtube about this,i know the flywheel is marked for each cyl to set the valves,,

they are good motors,but check the vin and make sure it didnt have the ceramic lifters mack was experimenting with,you have to keep the overhead adjusted or the lifters will wear out the cam,mack eventually went back to the tool steel lifter,the turn signals should be simple,check the wiring in the back for a short,