67RModel

The orange needle is for the secondary air system. Usually the low pressure indicator (buzzer) is tapped of the secondary system supply tank. There is a one way check valve at the inlet of the both primary and secondary tanks to prevent supply air coming from the compressor from flowing back into the compressor and/or air dryer and/or wet tank. It sounds like the check valve at the secondary tank is stuck or failed.

That is about the exact use case that 690s was specd for....

The pattern is literally like a 5 speed pickup truck plus you have the two under gears in holes 1 and 2 which you probably wont use that much. The big difference between them and a Fuller or even the 9 speed you are driving now is the rpm drops between gears. Once you understand it and get used to it they are very humbling and pleasant to drive.

Having more gears on the high side is always more helpful than not having them. If you are purchasing a used transmission from a salvage yard there is no guarantee about what you are getting. If you are getting a reman unit they probably will not accept your 10 speed as a core so there may be more cost involved. the 13 will require a different stick or a at least a new knob than what you have in addition to a little more air plumbing to the knob. Also, the 13 speed is longer than a 10 speed due to the auxiliary box. You will need to have your drive shaft shortened if you switch to a 13. I'm not sure if the mounting locations and cross members are the same for each transmission but that is another thing to check before you make a decision. Do you have an Eaton or Mack Transmission currently?

Its one of those universally unanswerable questions. It depends heavily on region, type of truck, future usage of truck, budget, cash flow, and your mechanical skill. For instance I would be more uneasy about a steel body dump truck with 500,000 miles that spend its entire life in Pennsylvania versus a highway road tractor with 500,000 that ran the interstate between Arizona and New Mexico. For me regardless of type of truck I seek out an example that has no rust or corrosion and good sturdy frame rails for the application. After that I look for the powertrain that meets my specifications and then evaluate the mileage after these criteria are met. If a truck has been maintained and cared for higher miles should not necessarily scare you away. There will come a time however, where everything will need worked on or replaced its just a matter of when. Also, with 20+ year old trucks there is no guarantee the ecm mileage is correct either. The ecm could have just as easily been replaced as odometer gauge at this point.....

It looks like you are allowed 34,000 on the rear tandems and 18,000 on the front for a total GVWR of 52,000. You are not limited to a lesser GVW by the components of this truck since it has 44k rears and an 18k front axle with 385 float tires. If we assume it weighs 28,000 you can net 24000 pounds, which is 12 tons....I assume if it was a triaxle it would be allowed to gross 73,280 lbs which is how it is in PA. With a drop axle it would be around 30-31,000 pounds. 73280-31000 is 42,280 pounds or 21 tons. "Legally" for hauling weight a tandem is kind of useless as you can see. The truck will easily haul much more than 12 tons as is but you wont be legal. And as stated previously the drop axle provides the additional carrying capacity to get to 73280 GVW as well as additional braking power to stop it.

I don't know where you intend to run this truck (which state). I see its being sold In Arkansas. I'm not familiar with the axle requirements for Arkansas or whichever state you live in. But yes in my opinion for a truck that clean and well kept $38,000 is a reasonable asking price if it were a triaxle (having a drop axle) in my area. Tandems have a purpose but they are not as sought after and in my area they are almost non existent. You could add a drop axle but that is a whole different subject. Yes a drop axle allows you to carry more weight but more importantly provides more braking. If a tandem suits your needs and you can make money with one I wouldn't hesitate for a second if everything checks out. I would definitely rather have a nice old girl like this in my stable over one of these new fangled, over engineered, sensor laden piles of rolling crap they sell new as trucks for a cool $150,000+. At least you can fix it yourself and won't be riddled with weeks of downtime while the stealership "technicians" try to figure out which loop of electronic wizardry caused you to go into limp mode while pulling a 8% grade fully loaded........That truck is a literal block of granite and will probably outlast most of us if taken care of and looked after.

Looking at the dealers website listing and photographs that looks to be about the most robust, reliable, and efficient dump truck you could probably find. Certainly not the most glamorous or comfortable out there but definitely an absolute workhorse money maker as long as the major components check out OK. I would want to see more pictures of the double frame rails and chassis but from the pics it certainly looks like a good clean southern truck with little to no corrosion. In person I would obviously want to check the engine for blow by and/or overheating head gasket issues. Check the transmission for any whining / bearing noise. Also, another thing to look for on these trucks is if the rear trunnion is in good condition or needs rebushed. A quick and dirty way is to raise the bed about half way so you can see the tandems out the back window and drive in reverse about 5-10mph. If the tandems track straight they are "good". If they walk around side to side while backing they need rebushed. Not the end of the world but something to consider when negotiating a price......speaking of which I'm curious as to what the price for this truck is.

So many guys jump into one expecting it be just like a Eaton Fuller 8LL and promptly wind up jamming and grinding gears then get all jacked off and trash talk them. An 8LL has about 400-450 rpm drops between gears. a 2070 has something like 650-700 rpm drops between gears. You essentially have to wind each gear out to the governor and shift. And like Jojo says take a long pause (light your cigarette or take a bite from your sandwich) before slipping it into the next higher gear (usually around 1050 or 1100 rpm) right where peak torque is on these engines. Down shifting is the other downfall of people who don't understand them. Pull the engine down to around 1100 rpm, double clutch to neutral, then rev the engine up to the governor and push the shifter into the next lower gear. Most newbies just "blip" the throttle like you would shifting a Fuller but its not enough on these Maxitorques. The space between the gears is about 300 rpm more than a Fuller.

I own and run a 1994 RD690S dump truck with an EM7-250 and a T2070 7 speed and can share my experience: Mine is 50 horsepower less than the one you are looking at. These trucks are not race cars and were never intended to be. The are slow, deliberate and reliable. I run mine doing steel body hourly dirt work so I'm not in a hurry to get anywhere....ever. The second you try to rush the truck, get in a hurry, or think you can pass someone else you will be disappointed and/or frustrated. So many guys I run into say the despise the "puny" 12.0L Mack engine and/or the Maxitorque transmission. The seven speed is an excellent dump truck / vocational transmission in my opinion. It is essentially a 5 speed (has 5 holes) with a deep reduction button and holes 1 and 2 are lolo and low respectively when deep reduction is engaged. I drive mine like a 5 speed 85% of the time. If I'm starting out on a hill or off road I will use lolo or low depending on the situation. Lolo is the perfect gear for idling in front of a milling machine. Same with lo reverse. You can idle backwards under just about any load and have excellent backing control. Mine has 6.06:1 rears so its only good for about 62mph on the highway. Every EM7 with a T2070 I have ever seen has crazy low gears in the rear (anywhere from 5:32 to 7 something). This is how so few gears are achieved in conjunction with an engine that will pull down to 1000 rpm. Once you realize what it is and what it isn't you will be fine. Just don't expect it to be a 550 Cat with 3.90 rears and an 18 speed fuller. The other thing too is the engine / transmission are extremely reliable and use very little fuel compared to other contemporary engines. Very inexpensive to operate in comparison.

Wouldn't this be equal to having low coolant? I mean if your trying to diagnose a bad coolant level sensor you need to have voltage or continuity across the plug. Unplugging it is the same as having low coolant level? I think you would want to unplug it and jump the harness plug with a paper clip or other conductive wire. If it starts and runs with the harness plug jumped then you could say the level sensor is malfunctioning. I could be wrong but that is how it works on my non electronic E7 where all the sensors do is give you an alarm and warning light in the cab.

It would help to know what year and engine model we are talking about here. Also what engine control system if known VMAC I, VMACII, VMAC III, etc.

Yes Mack owned Brockway at this time. Mack purchased them in 1956 and kept them an independent operation up until the were dissolved in 1977.

This is sadly an accurate but scary statement. A 99 is technically getting old now. Time has been flying by......

That is kind of nuts when you think about it. Could you imagine the carnage if you flipped the switch to engage Husky Drive and for whatever reason only one of the differentials went into high range? Were they air operated or electric 2 speeds? All the 2 speed Eaton "Double Duty" axles I drove in medium duty ford F700s were electric and I remember several 2 speed motor failures.

Was the tandem axle option a single drive 2 speed rear with a "dead leg" or a live tandem both having 2 speeds?

Hidden to me in plain sight. Thank you for this. Interestingly I know where this is and is only about 15 minutes from where I live. The exact location is now a Hunter Peterbilt/International dealer now. What was the difference between the factory branches and dealers? I assume the factory branches were owned by Brockway corporate (Mack)? Was there a difference in what was offered (inventory, service, etc.) at factory branches vs. dealers?

I have always wondered who/where the local Brockway dealers were in Pittsburgh, PA. I have asked may old timers and nobody knows or seems to remember. I now understand why: It looks like there weren't any. This is hard to believe considering how large of an industrial complex Pittsburgh and the surrounding areas were at the time of this publication. I always though Brockway had a much larger presence than they apparently did. What were their total yearly production numbers compared to Mack?

I am having a similar problem with my mechanical E7. It’s most likely a problem in the pump and in my case some people think it’s probably the governor, which makes the most sense in my case

That is what I was thinking. From the other pictures the interior looks just as clean if not cleaner than the outside. The description says 95% restored so it probably is turn key. For someone who wants a collectible Mack and doesn't want to or cant do the work to restore one this one is tough to beat.

Just curious what is the actual cost to get one recast if you know? I did not know there were companies doing this.....

Also, I guess it depends on how long you plan to keep the truck whether or not doing all the fabricating for the Eaton is worth it. Plus I think on resale (if you ever decide to do so) you will appeal to a much larger group of buyers if it has an Eaton transmission in it.....

My anecdote on this is a friend of mine owned a trucking company up until he sold out a few years ago. He had about 35-40 trucks (all Mack mostly Granites) in vocational and short line haul applications. He would generally buy used trucks and the transmission was always the wild card of the spec. They usually had Eaton 8LLs or some variety of Mack T310 or T310M. Most of the trucks got abused some more than others. He is a die hard Mack guy but never had anything good to say about the Mack transmissions from his experience. He said he could get a Fuller rebuilt for less than half of what a Mack unit costs and could get a reman Fuller unit the next day for half the cost or less of a Mack reman. Plus the Fullers could take the abuse - they just keep going. The Mack transmissions had significantly more failures in his fleet. I know we are talking 18 speeds here but I think the overall consensus on this site and just about everywhere else is its really hard to beat and Eaton Fuller transmission and its almost impossible to economically justify a Mack transmission over an Eaton.

One does not have to be an expert to find basic information such as this. I used that link out of convenience and due to its credibility. I trust your government's published data as peer reviewed research done by actual experts point to an almost identical set of percentages. This is the correct take. Policy makers will do what they do. The dollars and cents will follow the decisions of said policy makers and the world will continue to exist long after any of us are gone regardless of what the facts or our opinions are. As for the rest of this I will do as the old proverb says: Let sleeping dogs lie. Or with a site specific twist> let sleeping Mack bulldogs lie.

Saw this gem posted on Facebook marketplace. Says it is spotless and has a 250hp engine and a quad box. Clean title in hand. Not mine but I thought others here would like to see it. https://www.facebook.com/marketplace/item/350681283397697/?ref=search&referral_code=marketplace_search&referral_story_type=post