burnstransport

New Hampshire they're floating around from weigh station to weigh station, not as well funded as Massachusetts where the weigh station on I-95 in Georgetown is open for 72 hrs straight! Here in NH it's a guessing game who will be open today and tomorrow!

I have a question about a truck I drive at work, the beast at question is a 1993 Mack DM 690 SX, 58K rears, double frame, MaxiTorq Extended Range 7 speed, 317K miles, tag on motor says EM7 300. What I have read online is the EM7 is a computerized motor, but this one appears to be a mechanical beast having fuel lines going between each injector to fuel pump / governor. Accelerator pedal uses a mechanical bell crank & rod setup that rivals the complexity of a Rube Goldberg Invention to get power from governor. So my question is was the EM7 a mechanical motor in 1993? Or is it computerized and I just do not realize it. Also, anyone have good experiences with these motors?? This one drives like a real dog, no power whether empty or loaded, shows no unusual signs of smoke, pyrometer never reads above 750 deg F, coolant temp never above 180 deg F, just CANNOT climb a hill on the highway to save it's life. All filters / oil serviced regularly in the last 7 years that we have had the truck. Can I expect this kind of performance from this engine / tran combo or am I in need of some major repairs in the road ahead????

Silicone sealant or thread sealant??? How about thread locker????

Yes, I can see the drips forming along the bottom edge of the cover when the fluid is warm.

Hi everybody, I drive a 93 DM690SX with 58K rears. The rear-most differential LH side cover was weeping oil so I removed it, cleaned off the corrosion and replaced the O-ring. It still leaked (worse) so I replaced it with a new, "updated" cover from Mack which was made of some plastic composite. The parts guy and one of the mechanics both told me it will likely seal better than the older aluminum cover. Well after driving it into the city and getting oil nice and warm, guess what . . . . still leaking Is this a common problem, do I need to use RTV in addition to the O-ring? Also, what type oil does that need? The Mack mechanic said it takes 80/90 which is what I have refilled it with each time. Are these differentials prone to cracks? I looked closely where this cover goes and don't see any cracks, do I need to look elsewhere? Any advice is appreciated, this job seemed simple enough and now I'm pulling my hair out. Thanks - John