m5040

Thanks, It is difficult to see with the steel fender down. I though there might be more to it.

I have a 1979 RD single axle, the engine model is stamped E J Z675. The Mack book I have list the "E" stands for Mack turbocharged diesel engine, the next letter should be an "M" for maxidyne (the truck has a 2 stick 6 speed). What does the J Z mean ?

It is also stamped 672 CID, 235HP at 2100 rpm

If it has the air to air cooler, check for a broken hose clamp or ruptrued hose (on the hoses from the trubo to the cooler and cooler to intake manifold. A damaged hose might just look like a small slit in the hose that will leak out the boost psi. Won't hear a leak at idle. I have seen trucks come out of the local garage and miss this,,,, I can't beleive it either. If the diagnostic equipment doesn't show a problem, it must be in your head.

I am in the market for a single axle dump again. I have found a couple of trucks, one has the 300 with 2 valve and the other a 4 valve. Other then the years built and I would guess better parts availability for the 4 valve, is there any plus or minus features with each? Durability issues. Both have engine brakes.

As far as I know, the CDL laws are mandated by federal law and are the same state to state. It should list your limitations on the back of your license. But it goes by the GVWR of the vehicle and what the vehicle was designed for, ie commercial vehicle. So if the GVWR (gross veh weight rating) is above 26,000 lbs, you need a class B CDL and if you add a trailer with a GVWR over 10,000 lbs, you then need a CDL A.

Vehicles manufactured as motorhomes/campers got exempted from this cause of a strong lobby effort.

I'm Restoring a b61 Mack And wondering when I'm done can I drive it with class R license I'm planning to reinstate my class A with this truck What rules and regulations do i need to go by. I live in colorado.

All things being relative, my GVW is 36 to 40,000

Thanks for the info. The hood of the truck had "Econodyne" emblems under Mack. The governor housing has a sticker listing econdyne. And there is a steel line that runs from the gov housing back to the shift tower. Seems like at least when it was new, it might have reduced the engine RPM in 5th gear to save on fuel, as peak fuel economy is at 1450rpms. That might be disconnected, cuse I feel no difference in any gear, just goes like heck. The only reason I have to shift is to control the road speed. It is my 1st Mack and I am totally impressed and don't want to buy a 237 if there is a BIG power difference.

I have a single axle dump with a 300/5speed and realy want a 6sp. Not sure if I want to buy a 6speed and convert the truck or look for another single axle that already has a 6 speed. My question is, I see a lot of ads for trucks with the 237 engine and wonder how it compares to my 300, which I am sure goes without saying is extremely powerful in this application! How would I expect a 237 powered tuck to compare pulling hills etc? My tuck has a 4/1 rear axle ratio, and around town (keeping the econodyne to the 1500-1600 rpm range have) I have squeezed 10 mpg out of it, which dropes to 7.5 on the highway

My cab has rust around the windows, gutters, and doors. How hard is it to swap cabs? Looks pretty easy. Do you open the windows and run a strap accross the roof ? Can anyone give me an idea what an air ride cab is worth in the US ?

U models are very similar to DM (dump and mixer) chassis. They are generally just a lighter chassis. The door tag numbers will tell a lot about the model (ex. U685S) Even though usually lighter chassis they can be spec'ed quite heavy. I have a U609T that was factory equipped with a 29,000 lb single axle rear.

Chuck

What was the truck with the 29k rear end originaly, a dump ?

I dont kown much about that model, sounds like a Renault. But you won't need a CDL unless the gross vehicle weight rating of the truck listed on the completed vehicle tag is above 26,000 lbs, (if you tow a trailer that is over 10,000 lbs, this will change)

Hey Guys

I hope this topic is in the right place. I am starting a small business and am looking into a getting something to haul with. I was thinking of just a one ton pickup or like a F450 but I came accross a 1987 Mack MS 200P with a flat bed, lift gate and 91K for under $5,000 Is this a good truck and a good deal. I do not have a CDL and from what I can tell I don't think I need one for this truck. I have always heard Mack's were bullet proof so it seems like it may be a good fit. My busness is hardwood lumber so I would be hauling logs and lumber. Seems like it would be a better fit than a one ton and trailer????

Thanks for your help.

Tim

So then the 1983 vintage EM6-300 should be safe regarding this issue and the Jacobs brake ?

If you see these break all the time with a Jake, is there anyway to check to see if the problem is about to happen without disassembling much ? I have a EM6-300 with a Jake.

i adjust them the same way you do.

Sounds like the valve is bad,bag is bad or a leaky air line. That valve should hold air when parked. only time it should louse air is when the cab moves and alows it to dump. Could you relocate the valve to a place that does not interfear?

Trent

Yes, I am messing around with it and should be able to do it with not too much problem. I just didn't want to reinvent the wheel so to speak and was wondering if there was an easy way that I overlooked.

You are right about the air leak, it is from a bag, the budjet comes into play and the leak is very minor (1/2 hour before leaks down)

Thanks

My R686ST has an air ride cab that would rise up after you built up air by about 1/2 in. Didn't look like enough. It had a newly installed valve so ? I made a new/longer (1/2") linkage rod that seemed to work perfect, I had the bottom of the cab level (and it would rise up about 1.5"). However, when the air leaked out, the 90 deg linkage now rotated into the cab shock, putting a dent in the outter shield, DOOOUBT !.

Does anyone have the proper instruction procedure for adjusting this ?

Does the plastic arm come off and respline ?

My R686ST was converted to a single axle dump, the numbers on the right rear axle tube (as best as I can make out) are FA49343P13 D23C. It has 6 whole/stud axle flanges. Can anyone shed light on its weight capacity? And what years it might have been made? It has stamped brake shoe tables if that matters.

Thanks in advance for helping

One other simple thing to check is make sure the brake pedal isn't sticking down just a little. Sounds dumb, but I got fooled by it once.

Another sign of this problem is the brake lights stay on.

Just go to a mack dealer and get one, they don't cost that much.I'm sure Barry could give you a price and ship one to you.

Thanks, I will do that

My water pump is leaking severly from the weep whole. Where is the best place to get a water pump? Anyone rebuild their old one ?

The owner says it is a R690T vin 9T6546, but he may have reversed the number, it is a early R (1967), his helper describes the trans as single countershaft, 10 speed 2 stick. It is a much nicer looking truck then the U model. In your opinion, is the drive line in the U686 superior enough to make that the better truck ? All things being similar (30 years of who knows). It sounds like the 10speed has a creeper, which is nice off road.

Are there any sites to look up your truck's specs by the VIN? I am looking at two trucks, S/N U686ST1004 and R690T 9T6546, I would like some info on what they can carry, trans, engines, axle ratios if any is possible.

I am looking to purchase a single axle and have heard about the effiecency of the older Macks, I have heard most trucks are lucky to get 5 or 6 mpg. What is the consensus and what GVWR/road speeds? Has anyone noticed a change with the ultra low sulfur fuel ?

In my search for a flatbed dump single axle, I have found a 67 R dump with a Mack ten speed trans, the owner says it is a maxidyne but he describes the trans with 1 countershaft. He says he shifts the trans like a 5 speed and only uses the aux for climbing a steep driveway etc. But reverse is in the 5speed pattern, so that tells me it is not a 6sp maxidyne. Can anyone shead more light on this ?

Can anyone advise as to what engine was in a U model with a small rear facing hood scoupe. The after cooler is round, I have seen many rectangle ones, but not the round type this one has. It also had many small fixed propeller type items within the top part of this aftercooler.

Thanks in advance