MACKS

Rob, how hard is it to replace the roof on the R model I have to do something with mine its rusting all along the back. Thanks for any info you can give me.

80-90 is your best bet for year round use ,it's what mack recomends.

It sounds like the problem with your tranny is comeing from the back end of the box, you can remove the back end with out pulling the whole tranny, just disconect the linkege to the back and unbolt it pull it straight back, one thing to watch for is short peice of copper tube in the end of the main shaft dont loose it and when you put the tranny back togather dont use any siicone, thats what happened to mine a small peice found its way into the main shaft and pluged the oil hole under one of the gears. Also most of the whine you hear in the quad box comes from the berings on the back end of the out put shaft they must be ajusted right, if you have the back end rebult the tranny shop will set them up for you. Good Luck

I can't wait to see the price tag on that truck.

If you put more fuel to it, it"s gona need more air put the big blower on it, the some one thats on a 300, but why are ya messin with a good thing, the 237 was a great motor set a factory spec.

Do you have the drum type parking brake on the back of the tranny if so make sure it's not loose, I always had a problem with mine the bolt that holds the flange to the output shaft would loosen up and make it vibrate. You gotta push real hard up and down on the drum to see if it moves.

OK Thanks for info, I must have the electric model I got to check it out I don't like the way it shifts from third to fourth it seems to hold to long but all other gears shift fine. Thanks

Bump!!!

I know a lot of guys running the four valves from the mid eighties with no problem.

Question for AutomaticMack, In one of your posts you said to keep your modulater cable in adjustment, on a 90 mack would I have one if so where is it and how do you adjust it, and what does it do. Thanks for any info. the tranny is a ht750.

Used is the way to go in the dump trucking business in fack I think its the only way unless you have some kind of great account, I work in new york, mostly asphalt I'm very lucky if can get 140 days a year. at 640 a day you do the math!!

I own a 1990 mack rd ten wheel dump with a ht750 als. automatic and I like it a lot, It only has a 275hp four valve but it runs out great and is even better off road ya cant stop this truck in the mud and soft sand.The only problem is when I drive it once in a while my left foot keeps going for clutch pedal.

To answer you question, I've only seen one out working here on long Island it was green cab and green dump body the truck was bran new first day working on an asphalt job. It held up the job all the drivers were checking it out!

If your talking about a straight five speed I don't think your gonna like it, you wont have a real low gear for off road. Whats wrong with the ten speed or go with a six speed low hole. The eaton fuller web site has a calculator for figuring the mph.

Big mistake on there part!!

Those are some nice trucks, so many people ask why did Mack stop makeing the RD, I don't have a clue does any one know why?

I'm with fullfuel fix the leak first, if your losing pressure at the injector it wont spray the fuel the way it's ment to.It's just a couple of copper washers at the top of the inj. No need to take it out to fix the leak. Good Luck

I have never added oil to the top of a mack rear after the first fill, the oil from the bottom is splashed to the top of the rear and overflows back to the bottom, I beleve it says on the side cover for initial fill only. Gonna take a look in the books just in case, hope I've been doing it right for the last twenty years!!! Thanks HK I feel beter now.

I would check the ground wire that goes from the motor to the frame, I had that same problem on my DM and then it happened to my RD make sure the ends are clean and tight. Good Luck

How do you guys set the timeing on your mack motors do you play with it till you think it's right ,or do you have it done right by letting a mack machanic do it. Mine has been changed from the factory setting by the previous owner and I think it's off a little. With the price of fuel I could be wasting a lot of money. Does anyone know how much a mack dealership would charge to do it? The motor is an E 6 315. Thanks for any info.

Quit a few years ago I installed the gray interior kit in a 71dm it fit great only problem were the back wall corners you have to do a double fold and it fits nice no problem with the headliner and radio console, it was a great up grade for an old truck made it a lot more comfy.

You should set it up to the orignal factory specs if you want a good runing motor, I have that same setup in my 83 rd If you want I could get the numbers off the turbo and pump If that would help you. Thats if you have an E6 315R.

I Just want to say hi, my name is Gary, I'm from Long Island, NY I have been in the dump trucking bussines for the last twenty years, I only run a few trucks and they are all macks, I also own a single axle B-Model it's a single axle tractor with a short dump trailer. I drove that B for about six years before I started my dump business, they were good times for sure. These days I haul mostly asphalt for a big paving company, I drive an 83 RD with a 315hp, 12speed trans, It has a 20 front 58rears and a 14ft J+J box. I also own a 90 RD with an automatic, a 71 DM600 and a 71DM800. The dm800 was my first truck 237 quad box I use to love to shift that quad I could keep up with the 300's on flat road. I have bunch of pictures I'll post some soon. This is great site good people and a lot of good info, thanks for starting it Barry.

bulldog man-the electrical system will not keep it from starting if your pull starting, since you changed the fuel filter you might have air in the system, if you have a primer pump on the side of your injector pump loosen the inlet hose where it goes into the injector pump and then pump the primer until you have a steady flow with no air comeing out, tighten the hose and give HER a pull. If your getting good fuel to the injectors SHE should fire up. Good luck with HER!! PS make sure the fuel shutoff lever on the pump is all the way open.

Thanks for the comeback phildirt, I found my mack manual and it says for the 1.1/2 fine thread 2409-2911 ft lb and the 1 3/8 fine thread is 1849-2231.