The Nitro

The mack dealers have no idea whats in it as their build sheet shows drum brakes all round and spring suspension. I had to ring meritor to find out what brake pads to suit as mack dealer send me drum brake shoes according to records with vin number.

Old owner said that a previous haulage company that bought the truck new was pulling 2 trailers behind it and put a new motor in it around 2007 (different year engine i suspect due to weird wiring in behind dash along with the dash cluster from donor truck i suspect as theres abs light in dash but no abs i can see on truck)

its got the ea7470 motor with no polution gear or exhaust recirculation that i can see and has the powerleash brake i think as theres no spacer between tappet cover and heads.

its a grain tipper with sleeper cab.

Theres 2006 on tag on one diff so i think someone has maybe replaced diffs from drums and springs to airbags and discs at some point but i dont know what truck the diffs came from

Front drive diff tag:

Here is new 2024 cans. See how the thread doesnt allow the rod to become as short as the brakes on truck. I would have to cut the shaft right near can and weld the old eye on with only the weld holding and no threads. This makes me nervous. Im hoping to get shorter cans that look same from factory without me welding. They are MGM brand on truck

Heres a pic with brakes on. The truck mechanic said he adjusted them a couple months ago when he inspected it for rego saying they arent allowed to go past 90 degrees on lever brakes applied.

The truck has meritor axles all round but have mack stamped on the tags on diffs.

the drive axles are 160 series meritor running dx225 disk brakes and the cans are located on the front side of axles.

Here is a picture with brakes released. 

I opened the box with new cans in it and the rods are a mile too long.  Even if i screw the eye all the way down to end of thread it would still be too long. See on my can pic above the rod barely sticks out of can before the eye and the eye is welded to rod with no threading visible its just plain rod. The new cans rods are threaded to within say 3 inches or so of cans. Will have to take them back and see if they can get shorter ones with welded on eye or threads that go all the way to can and cut excess off. Dang it. 

Thanks for the help. Will post back when i find the problem

Now the damn leak is stopped. Its intermittent. Tried pumping brakes and park brake and dumping air tank and I cant get it to leak. But it will wait till another time then leak again. Guess I just need to try wait till its leaking then undo the hoses and see.

while its leaking I see all the brakes try come on for a couple seconds and while the brake rods are jumping in and out a bit that flap valve has aic coming out the bottom then it just stops leaking and brakes return to off.

no luck today for a fix as I cant hone in on the problem unless its leaking 

Heres a picture of a spring brake thats on truck

Ok i will start disconnecting thd maxi lines but will have to keep truck running i suppose to see which ones leaking. I still dont understand how the air leak stops when i turn engine off.

Ea7 470 hp motor and 18 speed roadranger crash box with a very stiff clutch pedal lol

Its s 2004 mack vision tip truck with doff locks and cross locks and full air brakes

Then these 2 valves are also on right side of truck chassis (standing behind truck) closer to cab than the last valve above i showed but I dont know what they do.

the valve that leaks air out bottom is the new one that sends air to all brake booster ports closest to rods but stops soon as trucks turned off even though all air tanks still full

This valve is on other side of chassis and the black hoses lead to the front and rear dual diffs brake boosters ports farthest from the rods

This valve is the new one which is leaking just the same as old one I took off. It sits on left (standing behind truck) hand side of chassis just in front of rear diffs. The black hose on right leads to front dual diff brake boostes at the ports closest to the rod that comes out and the black hose on left leads to rear diff brake boosters at the port closest to the rod as well

I dont know why? The truck according to mack dealers via vin number has spring suspension and drum brakes but truck has meritor air bag diffs and disc brakes all round. Also according to registration papers the truck has been upgraded from 70 tonne gcm to 80 something tonne gcm.

Ok will get some pics. 

Hi guys, just got time today to investigate this air leak problem and I have bought 2 new 20/24 spring brakes. I have not put the new ones on yet. So, i start truck and get air up, release the brakes and I get the air leak out the bottom flap valve.

I turn truck off and almost Immediately the air leak stops. If I turn key on again the leak is not leaking.

If I restart truck The leak starts again???

I have not disconnected any lines yet to see which spring brake might be faulty but this leak stopping when I turn truck off has me puzzled. How would the spring brakes know the truck is running or not, an oring in spring brake can’t fix itself with truck turned off and then damage itself once trucks re started so I’m trying to understand what happens to this leak stopping when engine gets turned off?

wouldnt a leaking oring in spring brake  keep on leaking whilever pressure is on the line?

is there some valve that disconnects spring brake air when motors off?

was hoping to have motor off so i could hear which spring brake might be leaking but it stops leaking soon as i turn truck off lol

Ah, ok thanks guys I will have a look at the brakes and see If I can find which one it is.

I’m not confident to disassemble a chamber safetly so might just replace the whole thing. I seem to be getting to know Andrew (mack parts dealer) pretty well now hahaha. Thanks again for the help.

Hi guys,

I have a 2004 mack vision tipper thats leaking air out of this air brake part with air brakes released.

if i put my fingers over the flap on bottom where air leaks out to try stop leak then I can see all 4 rear brake come on. I replaced the valve with a new one and it still does it?

it sits on chassis just in front of the dual axles. Something else might be wrong but not sure where to look.

any ideas?

thanks.

Got the ram back in this arvo and looks like we have had a win. No leaks and it goes up and down but I didnt like the looks of the oil that I released out of the air bleed bolt at top of ram to purge air. Looks contaminated with specks of perished hydraulic hose interior sidewalls. I will give it some new hoses  and a bit of a tank cleanout I think.

I like pictures on repair type jobs. Silly mistakes can be picked up on by the more experienced and gives everyone a bit of entertainment at the same time. I’m looking forward to getting this rig registered and on the Rd. Glad to find a great Mack forum where I can get a bit of help with things on the truck.

Thanks Guys.

You should see my 1959 david brown 900 tractor loader with the blown up engine I got going by welding a toyota pickup engine and gearbox into with the tail lights off a boat trailer for my dashboard then Terry. The guys on that forum wanted me to take a picture of it with a stick duct taped out the front with a can of aerostart hanging off the string for their yearly club calander 😆

Easy as that 😃