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Mack Truck Question

Discussion in 'Heavy Equipment' started by ServiceOnSite, Feb 21, 2009.

  1. ServiceOnSite

    ServiceOnSite Senior Member
    Messages: 950

    ok a couple of question about a 82 mack dump truck im looking at buying. First off is the name of the cab. Its off set to one side. I that whats called an r model??
    Next is how good of a motor is a 237 ??? only has 70k on a inframe 230k total on truck.
    and last question is what should this truck do top speed safely? can it go on the thruway?
    i dont know what the rear end gears are i drove the thing down the road ( its not on the road ) and before i knew it i was in 5th gear. at like 40ish. just wondering how high this thing might spin in the rpms and whats safe. are there any big things to check on this truck known problems, or something that if i miss ill hear " oh man he bought one of those " or " those things only last 40-50 thousand miles before that 3 thousand dollar part breaks "

    any info would be great thanks in advance
  2. lamarbur

    lamarbur Senior Member
    Messages: 125

    I've owned basically IH-Navistar and on a few ocassions, many, many years ago, drove what is called the "U" model Mack that is the offset cab,.. I found that where I live, very hilly area, the 237 was underpowered badly for a dunp truck. Your out Buffalo way, is basically not a bad area and a 237 would fair much better there,.
  3. blowerman

    blowerman PlowSite.com Addict
    Messages: 1,275

    Mack's off set cab is the DM model. The idea is to give the driver great visibility to the drivers side for backing. As for the 237 motor, not much power and slow on the top end. I had a 93 DM with the 300 motor, just dog slow and by 55 it gave up. Traded it for the KW's and never looked back.
  4. cat320

    cat320 2000 Club Member
    Messages: 2,224

    I have to agree dm, 237 could not get out of it's own way .
  5. JD Dave

    JD Dave PlowSite Fanatic
    Messages: 11,194

    The 237 Mack will do all you need it to do and is hard motor to kill. Mack engines, trannies and rear ends are almost indestructable but they are pretty rough trucks to run. We have an 87 still and it's still runs like new.
  6. Mr.Penndel

    Mr.Penndel Junior Member
    from Penndel
    Messages: 5

    First off in 82 it was a DM. As far as the 237 it is a great motor and very hard to kill. If you do burn the motor up it should be cheap to rebuild. what pound rears are in it? Also are you going to be the one running it everyday or is a worker of yours?
  7. speedy

    speedy Senior Member
    Messages: 104

    You can run them (in top gear) at 2400 rpm or so all day, no problem, except for the fuel consumption, and Macks aren't to bad in that department anyways. the engines put out maximum torque at 1200- 1400 rpm - you can hear them get into that 'power-band'. Shifting up to the next gear is best done at 1800 - 2200 rpm - you'll figure out what works, too low and the next gear will struggle gaining speed again. Same with the down-shifting...you'll soon figure it out.

    Overspeeding the engine (2800 - 3000 rpm) on down-shifts is what takes out the main bearings, so be mindful of that.

    Keep spare fuel filters on hand, when they plug up, it's a nearly instantaneous loss of power. Is it equipped with a pyrometer? - that is a very good indicator of how heavy you are taxing the engine, keep it under 1100 degrees for sure. A manifold boost gauge is a good thing to have too, if you can get it to pull 24 psi it's working well, 28 and above, it's a real workhorse.
  8. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    i drove one a few years ago and empty or loaded it would run 65mph loaded it just took a little longer to get there. only downfall on Macks is the rear suspention. check the trunion out real close for cracks especially around the bolts. Like said already the engine trans and rear are almost indesructable, the on i drove was an 86 with over half a million miles and ran great.
  9. santaclause

    santaclause Member
    Messages: 58

    237s are tough and like stated earlier cheap to rebuild,I take it she is only a 5spd,no hi lo some had two sticks 5 main and lo hi rev on other stick 5 rev gears, I have always liked macks ,I drive tracot rtrl and had driven quite a few macks and wish the place I worked now used them
  10. ServiceOnSite

    ServiceOnSite Senior Member
    Messages: 950

    So is this a U model or a Dm??

    Yes its only a 5 speed no hi lo one stick

    No gauges i will end up putting them in if you guys say its a worth while investment

    I dont know what pound rears are in it yet im getting the speck sheet this week

    If this thing is this much of a dog is there anything i can do to turn it up? like turn the pump up for more power or do i have to go the route of putting a bigger turbo on it or something????

    thanks again keep the info coming please
  11. Cat Man 77

    Cat Man 77 Member
    Messages: 69

    it is a DM, 237, 5 speed. most likely 55,000 Rears. it will probably top out at 55 MPH or so. personally i would not want it any faster than that. that's all the tires are rated for. personally i prefer R models just because the cab is bigger. all in all this sounds like a good truck. one more question are they tubeless tires or not? do you have any pictures? hope this helps
  12. ServiceOnSite

    ServiceOnSite Senior Member
    Messages: 950

    i dont have any pics yet i think the tires have tubes. if there not floater rims then they have tires right????? what the different in the cabs then just the interior size right???
  13. speedy

    speedy Senior Member
    Messages: 104

    The pyrometer is the best investment of the two. A boost gauge is more for shits 'n' giggles, but it will also let you know if it's performing at it's best and helps with indicating whether a serious problem is occurring, like a leak in the aluminum aftercooler/intercooler or a brokent rubber hose in the intake system....this can suck dust into the engine when under vacuum, instead of pressure. (been there, done that, paid the bill 8^( ) Low boost will also tell you if the filters are starting to plug up. I'm not sure if there is a possibility of adding a secondary box behind that 5 speed, but if so, the extra gear4s would do way more for the truck's performance than bumping the fuel pump. What that truck is lacking is gears more than anything. There will be a huge rpm drop between shifts. I'd think 750 - 800 RPM or so....It would be ideal to tighten it up to 400 and keep it in the power band. Or if the tranny ever needs to be replaced, a 9 speed would be a great choice too.
  14. blowerman

    blowerman PlowSite.com Addict
    Messages: 1,275

    The DM is off set to the left. RB Macks had the same strange look, but were centered. I'll agree the 237 in rock solid, but still slow getting up to 55 stay alive. My guesss for the rear end is 44K. Any less and you'll just snap the axles. Could be a 38K?
  15. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    most of them have 44K rears, the one i drove was built for local heavy haul and it had 60K rears, that was a very rogh ride. Oh ya it had 2 sticks in it to.
  16. tjctransport

    tjctransport PlowSite.com Addict
    Messages: 1,390

    look at the plate on the door. if it is a DM, it will have a VIN starting with DM. something like DM686, or DM886.
    if it is a U model, it will be U686 or something like that. the VIN tells the series, and the weight capacity of the truck.
    the 237 does not have an intercooler or after-cooler. turbo only.
    the 237 is a good engine, and will run forever if properly maintained. it is not a speed demon though. kinda like a 6.9 ford diesel in a pick up. it will pull a house down, but take forever to get up to speed.

    is it a tandem, or single axle??
    as for cab size, the interior of the DM, U model, and R model cabs are all the same. the only difference is that the DM and U models have the cab offset to the driver side about 12 inches from center.

    what are your plans for the truck?
    are you going to use it for an on-site truck, or is it going to be used as a daily driver money maker?
    another thing to consider with "turning it up" is that these trucks get real "dirty" when the fuel delivery rates are messed with, and will easily fail exhaust opacity tests.
  17. Cat Man 77

    Cat Man 77 Member
    Messages: 69

    Thr RB mack has a set back axle like the DM but the cab is centered on the RB. a RD or R model has the cab centered and a set forward axle. i know guys with a mid 80's with a 237 6 speed with 38K rears and have had no problems with the axles.
  18. ServiceOnSite

    ServiceOnSite Senior Member
    Messages: 950

    Ita a tandwm axel truck that i plan on hauling broken concrete with, everyday use would be great if i had everyday wrok for it. who knows what this year is going to bring
  19. DGODGR

    DGODGR Senior Member
    from s/w co
    Messages: 641

    I think you (as you can see from the thread) that those old Macks are almost indestructable. That's kinda how they made a name for themselves. I would not go into it thinking you are going to "tune it up" like you can with your pick-ups. This will cause you more headaches in the long run. This truck will have enough power to get you and your load to wherever you need to get but it won't accelerate or stop like a car or even a pick-up. Don't worry about being in a hurry....you'll get there. As a previous poster suggested it would be better if it had a "brownie box" (second stick) but it doesn't. I would not recommend swapping components unless you or your mechanic is intimately aquainted with that brands systems and componenet set ups. You want to be sure that any componenet you add is COMPLETELY COMPATIBLE with the rest of the componenet group. That doesn't mean just making sure it fits. If you have someone that you trust for this (which your querries here suggest otherwise) you will probably avoid mistakes. If not you will cause yourself more trouble and $ than it's worth and end up wishing that you had just left well enough alone. Good modifications can be done succesfully if you do your homework. The problem is knowing which questions and whom to ask them of. You will also get much better info from this forum when you post the specs from the truck. Good luck.
    Last edited: Feb 22, 2009
  20. Cat Man 77

    Cat Man 77 Member
    Messages: 69

    how much do they want for this truck? from what it sounds like it needs interior work, and it has old tube type tires and maybe a split ring. what do you want to pay for a dump truck?