mudslut28

LOL This is gonna sound crazy but I dont even use a pyrometer on my old 2 valve 300 (285?). Pump is turned waaaaay up on it...will in fact turn the manifold and turbo orange on a hard pull. However it has been like this for the 9 years I have had it so I dont even worry about it. Exhaust temp doesnt seem to be as important to a Mack motor as it is the lesser makes. This is hauling 35-45 tons of coal on 5-15 degree grades so I would imagine you wont stress a motor much more than that.

Truck has a 6 speed so the motor/tranny should be about the same as yours.

Who'da thunk there would ever be a scammer in the trucking business? LOL

Been around them all my life. I bought my first in 1988. Hauled coal since then..nothing but Dogs for me. The Energizer Bunny was built around a Mack...

Gearhead Grrrl is right...lol. Only way to kill a Maxitorque is drain all the oil out of it and haul for a week.

My brother had one he hauled coal with. Never any motor trouble but it eat rears pretty frequently..lol. Usually hauled in the 50-60 ton range with it. Couldnt really expect the 44's to stand up to that beating on both ends.

Thats the reason I never would touch a Cat motor..... I can rebuild 4 or 5 Mack motors for the same price. Parts are absolutely ridiculous for them things. God forbid you have to pull a head on a Cat motor also..

I doubt if you broke anything inside the clutch housing- you just adjusted out all the free play and have the clutch partially released.

Yep, I thought it had locked up. But the lock was just extremely non-cooperative until I stuck a large bar to it Bad news is that it was nearly out of adjustment anyways and will have to be replaced soon anyways.

Ok dont laugh too hard but I adjusted the clutch on my old Mack backwards. Its got the new style spicer quick adjust clutch in it. Heres the problem....I went a few sweeps with the wrench clockwise out of habit...well it went so far and stopped and now the adjustment is locked up. I reallized after doing this that the new style clutches adjust counter-clock. Have I killed this clutch or is there any way to get it back adjusted the right way. Stupid yes I know...lol...but you'll have moments like this during the usual 80 hour week. I havent been back under the truck to try and see if I can get it back but I have a gut feeling it will have to be replaced now. 98% of my free travel is gone and I figure its just a matter of time. Any advice or help would be greatly appreciated. Thanks in advance.

BTW The old dog is working among 5 cornbinders and wearing them out on tonnage Them old 800's...lol....you cant kill em.

You can use 12x24's or 11x24's with the 8.0 or the 8.5 rims. The 8.5 inch rims take a heavier wider spoke though. Typical setups I had were the trucks that had the 8.5 rims had the heavy "offroad" spoke and used a 4.5 inch spacer while the 8.0 used the "onroad" spoke and used a 4.25 spacer.

After changing flats on these things all my life I cant imagine why anyone would ever wanna fool with them if they didnt have to. BE CAREFUL with them...they will breaK you down quicker than you will break them down.

Remember the slower (higher number) the rears the stronger the gears....

Mine always tracked wrong when it was time to replace the rubber blocks. Mismatched springs will do it as well...

Yes..it is an .60 overdrive. My 88 with 65,000 lb rears and a 7.58 ratio will top out at 62 mph. 1200 is about right on the money for down shifting.....however tight you can get it to turn is good for upshifting I have ran one hauling coal (35-45 tons) in the southern West Virginia Mts sinc eit was new in 88 with 1 bearing kit. The things are unbreakable. Mackattack was right in the fact that the 2 low gears are a dream for pulling out in bad places and hills. It is definitely an extended range tranny. You cant get in a hurry with them but they usually get a lot better over time on ease of shifting. High gear seems to be loud in everyone of them also.

My only kick was the darned splitter...you had to make dang sure you were in neutral before you flipped ranges are it grinded like it was gonna explode but after 17.5 years it still hasnt

Good to find a place full of Mack fans. I am 35 and have been hauling coal for myself since 1988 and was around them most of my life before that. I wont buy anything but a Mack so i should fit in well here. Good to meet you folks!

Packer is absolutely correct. I run the adjustor down till the jake it hitting slightly and then back it off 3/4's. Mack jakes arent great but they do ok. The dynatard on my 4 valve does a good job.

I know its outdated but I had one 9 speed and it had clutch pack trouble as well. I loved the tranny and the way it shifted but I didnt have any luck on reliability. This was hauling coal in an RD800 though.

THE 6 CYLINDER MACKS WERE OF THE SAME BLOCK WITH THE DIFFERENCE OF A COUPLE OF CUBES. THE ONLY THINGS THAT CHANGED FOR MORE HORSE POWER WERE THE TURBO, INJECTORS, PUMP, INTERCOOLER. MY DADS WORKED ON THEM FOR 30 YEARS HE SAID THAT THOSE FEW CHANGES IN CUBES DIDNT AMOUNT TO A HILL OF BEANS. MACK WAS ALWAYS KNOWN FOR BAD CAMSHAFTS( DYNATARDS) THATS WHY JACOBS BRAKES WERENT TO POPULAR. I THINK THE 4V HEAD WASNT MADE TILL 88. I GOT AN 87 WITH 2V HEADS AND HAD AN 88 WITH 4V HEAD AND TRENTS RIGHT THE BEST WAY TO TELL IF ITS 4V IS TO SEE IF THE INJECTOR COME IN THE SIDE OF THE HEAD (PASSENGER).

HOPE THIS HELPS JOE

Your Dad is correct. I had one of the first 4 valves in my 88. The damn thing had constant valve train trouble for the first 2 years and since i rebuilt it completely after it wiped the cam out in 91...it hasnt been opened again. The 4 valves made a lot more low rpm torque as well. Mine pulled hard down to 1000 rpm's....whereas my 2 valves is dead in the water below 1400. The 2 valve I turn to 2300 and the 4 valve turns about 1950-2000 tops. I like the driveability of the 4 valves (lazy shifter here) much more than the keep it wound up style of the 2 valve.

I might be wrong here but I cant remember for sure...but the first 4v motors had the L designation on them. I think the EM6 is a 2v as well isnt it? The 4V is an E6-300L or E6-(insert hp rating here)L. E7 was a little bit more cubes ( 720something I THINK)and a wet liner motor. E6 was a dry liner (no water circulating around the outside of the liners) and was in the 670something cubic inch range. The 4v motors also had the charge cooler in front of the motor and the side mounted cooler or the god-forsaken tip turbine were GONE. Those 2v motors were a pain in the azz to take a valve cover off to run the valves or to swap the heads on due to the weight of the front one with the cooler attached. Assembling the valve pans and jake spacers without leaks is also a nightmare where the 4v has the valve covers slotted so the gasket fits right in them. MUCH better design on the valve pans. The others who mentioned the side mounted injector lines are correct also.

Sorry to be long winded but I am bored and new to the site I wont swear to all of the above but it is true to the best of my memory..lol.

Do you guys remember the DM800 tractor being destroyed in the Seagal movie? Now that one made me sick as well. Think the name of it was Fire Down Below......that was a shame. They should have used one of the inferior off-brands that the junkyards are full of.

I dont think a 70 Model had an a-valve for pollution did they? My 76 doesnt my 88 does. As far as turning them up..in my experience a little to compensate for pump wear always worked well...but in my experience if you turn them up a LOT they pump doesnt seem to last nearly as long.

I can definitely relate when you talk about the smartazzes running someone elses truck make remarks about slow trucks. Both of mine have 300's...one a 6 speed and one a 7 speed. Hauling the average 35-45 tons they just didnt have the ooomph that the new non-Macks had. But the thing I always laughed at was the fact that the truckyards were full of JUNKED.....yes worn out junked Big I's and other assorted mid 90's and up various brands while my 30 year old "slow" truck hauls every day.

We may not get their first......but we will get there the MOST

I had an 86 RD800 that came with an E9-440. It had been replaced by an E7-400 when i bought it. Big difference in power but I always liked the E6 and E7's for the reliability. I had an 85 RD800 with a cummins as well. I love a Mack motor for simplicity and reliability but I loved that Cummins for the engine brake and the fact that it was a Big Cam 3 and they seem to last forever or until you finally turn a bearing...whichever comes first

Very Nice!! New member here. I have a 76 DM800 that i still haul coal with everyday in WV. They really are unbreakable!