Mack 285 Engine

[cheech147]

I'm looking at buying an 89 U model with a 285 engine and 5 speed transmission. I drove a a U model for years with a 350 and 5 speed. Hauling freight around the 45,000 lb. range it did o.k. Of course it wouldn't pull the hills like a 425 Cat, but it did fine with other trucks on the road. Was wondering if anyone out there is familiar with the 285's and how they perform.

[Lmackattack]

in their day they were pretty good when compaired to engines of the same era. many said that a good running 300 mack would hang with a 350 cummins or cat. I think one of the down sides to the maxidynes was that they liked the low RPS better than the upper RPM. this means the engine pulls harder the lower the revs are.good for off road but not the best for a hill. You will have to use 3rd on most hills pulling at 1400RPM thats about 30MPH or so. also with the gearing of a 5 speed you dont have that choice to spit a gear to get a little more MPH. if you can get over the slow hill climb issue you will find that the maxidyne will pull good in the first 4 gears and once you hit 5th your good untill a stop light or hill. Here In IL the 285 / 6 speed is a nice simple and reliable set up. if your in CA or in the hills alot you may not like it so much?

[cheech147]

Thanks L, it's a single axle and the price is right. I always liked that short hood even thought they bounced a little because of the short wheel base. Couldn't beat the U for backing up a trailer though. The reason I asked about the 285 because was thinking of stretching the frame and putting a screw on it for a tractor. I didn't know how much different the 285 was to the 350. It seems the key is that power band and trans combo regardless of the hp. From what you stated the 285 doesn't sound much different from the 350 I drove. I have a couple options with the use of it, guess I'll go with leaving it a single axle and mounting a dump body on it. I was considering stretching making it a screw. Wishful thinking.

[bullhusk]

Cheech, I think LMACK. is dead on with his answer, but I got a tell ya a Ready/Mix customer that I del. bulk cement too here in Jersey bought 4 DM600 with the 285 6speed's (Brand New) in 1986 he ran those truck's until 1999 an never touched those motors! oh and by the way he sold the trucks an didn't scrap em

[Lmackattack]

they did make great ready mix trucks. I think many speced them with the 6 speed with the ultra low low gear. you could start a fully loaded truck without the clutch. LOL just grab the shifter and find low low. all the slop in the gear box would not even bang a gear LOL!!! thinking out loud here. a 285 in a u model will have a few tight spots in the engine bay with that short hood. but liek Bullhusk said. they run for ever and need little attention. I have a 285 in my 1977 RS700L and its numbers matching. turn key truck. I can out pull a 427mack up to the top of 4th gear or about 45-50 MPH. When Empty It looks like they fell asleep at the light. It cant compete with the new cats or cummins but hell the new motors have 2x the hp/tq. if it can hang with it a little its doing pretty good. Dont forget its a 30 year old outdated diesel!!!! oh and the EPA wont like the black clouds like we do!!!!!!!!

[Mr. BowTie]

I had a Mack R688 with a 285 Engine set up in a wrecker. Had an air shift Maxitorque 5+1. It offered 3 reverse speeds! Anyway, also have a Mack CH613 1996 wrecker. The R688 with 285 pulled more weight, but never could do more than 48-52 MPH empty or loaded! The CH613 pulls loads easily up hills at 62-66 MPH. CH613 is a Mack Super 10.