Hey Guys, first post here! So I got a 1985 International 1753 6.9 idi - 28 passenger bus today that is getting 6 Mpg, 3,000 Rpm @ 55 Mph - top speed :/ (governed?). It's got 80,000 miles and probably hasn't run in years. Planning on all the maintenance: Oil/Filter, air filter, glow plugs/controller, injectors, return line kit, fuel filter. So what gives? Should I expect my mpg/top speed to improve after this or is something seriously wrong? -FIRST diesel, so I'm a total newb here. Thanks guys and gals!

*haven't checked rear end ratio

 

Whats the weight of the bus? Place i used to work for had a IH S14/1600 was about 18k loaded (always loaded). Would do 72 on the governor. Never actually did the math on the mileage but it was surprisingly good. Could drive all over in that thing and never did take much fuel.

 

Curb weight: 13,340

Lots of grey exhaust, maybe a bad injector?

*exhaust was black, then grey, then clear when hot, back to grey in stop and go driving.

 

Timing sounds way retarded, or combination of worn out fuel system. Grey smoke could be either. Black is overfueling. Id start with a compression check and make sure the timing is around 8* +/- 1*. Could be an injector, but you would notice the knock or miss.

 

What rear end gear ratio?