RS Disposal

not exactly sure where that is. I am not a heavy truck mechanic and still learning my truck all beit it is older

lately I haven't been getting anything out of the purge valve when the system reaches 120. I agree that the line between compressor and dryer should be replaced. It is definitely on the list of things to do with this truck. Right now I am also fight a fuel problem which I am hoping is old/bad fuel lines. The truck was never maintained as it should of been when my dad was operating the business and then sat for 20 yrs before I opted to put it back into service

i am working on replacing most of the lines one by one on this truck being it is a 1979. I know rubber breaks down just from age (not alot of miles but 47 yrs old) and this truck has seen alot of road salt. The problem I am having is that once it got cold the truck had a hard time building air. I replaced the governor which seemed to help a bit. Air pump was replaced about 5 or 6 years ago. Being a garbage truck it does alot of start and stopping.

the air dryer is fairly tall as compared to what I have seen on other trucks. Plenty of room whereas the dryer is on the inside of the frame rail and nothing else around it

I am wanting to service my air dryer being I can't find in maintenance records my dad had for the truck when it or if it was last done. I can't find a tag on the dryer or and specific info on it in the factory service manual. Not sure if I can actually get it apart being truck sees ALOT of road salt in the winter. If that is the case what style of air dryer should I be looking at. A google search shows there are quite a number of different dryers available.

OK, an up date on my problem. The issue is now that when climbing the canyon occasionally the truck will start to miss to the point I have to pull over and let engine idle for a bit at which time I can continue on up. Replacing the in/out fuel lines from the secondary fuel filter didn't really make any change. I replaced the fuel line from primary filter to the fuel pump, again with no change. Still have to change out the line from tank to primary, but that one is alot more time consuming because of the way the factory routed it. Thinking I will route it in a more direct fashion from tank to filter rather than down along frame to behind trans and across and back up to filter. The line doesn't appear wet anywhere, but being on the suction side I am thinking it might not be. This line being under the truck is exposed to alot of weather and road spray/salt. Plus the truck is 47 yrs old. Not alot of miles but I do know rubber breaks down because of age. just trying to learn my system also and whether or not this could be a problem. The first pic is of my intake manifold with where I assume this senses boost pressure and sends a signal to the injector pump. (where my finger is pointing) The larger line is truck air and the smaller is the one that goes around to the injector pump. The third is on the side of the injector pump where the small line comes down from the row of injectors and the larger line goes back to the tank. On another note the couple of times I have replaced/taken the secondary fuel filter of it hasn't been completely full. Maybe about 80%. In my way of thinking it should be full. Would this be an indication the air is entering my fuel lines somewhere between tank and injector pump?

I want to thank everyone for your replies. Please excuse my terminology whereas I am a small truck/auto mechanic, not a heavy truck mechanic. I am just a one man show with only one truck and I do try to do most of my repairs\maintenance myself. That the way my dad did it and taught me.. I may of found my problem, if not it was a problem only going to get worse. During some routine work I noticed a fuel line along side the frame rail going from what I assume is a fuel pump on the side of the injector pump the was wet and the under side of the truck and leaf spring also wet. My truck has 2 fuel filters. primary has the line from tank then goes to this fuel pump. From there the line goes to the secondary fuel filter and from there to the injector pump. I am assuming these last two lines are under pressure hench the reason the line is wet from leaking. The other lines are suction lines. I noticed that last time I replaced fuel filters that the secondary was only about 80% full. The line that was wet was the one from the pump to the secondary filter. So my thinking is that for whatever reason pressure was being lost and air introduced into the system. Replaced the two lines off the secondary filter and I guess time will tell if that was my problem. As soon as the weather gets a little better will be replacing the other fuel lines. Don't have a shop big enough to get truck inside so it is all outside work.😪

I believe the fuel tank is good. when I did run it lower on fuel I did shine a light into it and it looked clean

when I snap the throttle the rpm's don't run up. It immediately drops back down to idle. Truck doesn't have alot of miles, only 160,000. It's just old but other than the occasional surge it runs and pulls great

That was on thing I was thinking might be, a fuel restriction. When I changed fuel filters, thinking it was plugged filters, and I cut one open there was a black residue in the filters. My thought weas that maybe the fuel lines were beginning to deteriorate internally being the truck is 1979 (46 yrs old) I have purchased new fuel line, just haven't replaced it yet

This was the only tag I could find, but the pump was pretty dirty being the truck works in a very dusty enviroment

sorry about the dirty looking fuel pump. Best pics I could get being the pump is down alongside the frame rail

I csn try and look at it when I get to the truck tonite. Not sure how I would tell. What should I be looking for as far as the difference. Like I have stated I'm not really a heavy diesel mechanic. I can take a pic and upload it

I have a 1979 ENDT 675 Mack engine. Recently it has developed a surge at about 1500 rpm's unless the engine is under a load. Nothing around 1200 or upwards of about 1900. When it does surge the boost gauge remains steady. I don't think it is throttle linkage, but I could be wrong. Haven't tilted the cab to really look at it yet. It is definitely rpm related and not truck speed related. Any ideas as to where to start? You guys were awesome help a couple years back when the engine dropped an exhaust valve in helping me source parts and do the repair. nobody in my area wanted to work on this old truck and I am a light truck mechanic so it was definitely a learning experience for me. TIA Rob Shane RS Disposal LLC

I just remember my tire guy would ask if my wheels were budd when I need new ones

That I would hope not being these brakes are only accessible by removing the drive hub along with the drum. I will try looing thru the inspection hole on the backing plate to see if I can see anything

the cams get grease at approximately once a month when I do a pm on the truck

thanks, that was what I was thinking might be. This is a garbage truck and the dump is a very dusty place in the summer As far as the torque that is what I was thinking also being everything I found was saying the same. But everything I found was not saying anything about the older inner and outer lug nut style bud wheels

just the shoes were replaced and only one wheel. No noticed difference in stopping performance

Not really sure if this is in the right forum and it isnt necessarily just a Mack trk question. Lately occasionally my brakes will howl when I slow to a stop. I call it more of a howl than a squeak. The brakes were replace about 5,000 miles ago. No noises until just recently. Somebody told me this can be cause by dirt in the drums. Just curious and wondering what the cause is. My other question is about lug nut torque. I can find alot of info dealing with the newer trucks. But what about the older inner and outer steel wheel torques. Found a couple of broke studs which I am assuming was caused from being lazy and using a 1 inch rattle gun to tighten rather than a torque wrench. Going to replace all studs on the rear axle

I am not a heavy truck mechanic, but do have the mechanical inclination to understand what I was doing. I am a light truck/automotive mechanic so I must admit the the larger engine, etc was a little intimidating. I asked ALOT of questions and solicited opinions on alot of subjects from head work to camshaft/lifters to cooling system. With all the help etc I was able to get my trk up and running and so far it is running great. I no longer overheat going up the canyon empty even in the winter. I can now do this even with a load on and the engine never gets over 180 and daytime temps here have been pushing triple digits. There were a dozen or so that helped me, but right off the top of my head was Geoff Weeks, Joey Mack and Mrsmackpaul But I want to say thanks to everyone through my various posts.

I ended up buying a new Mack radiator. The core dimensions were all the same as the old radiator. But this radiator requires an expansion/overflow tank. I got an expansion tank off off a dead trk in the yard. From what I was able to see (this trk had a side mounted radiator) the large hose out the bottom goes to the lower radiator hose. My question is the two smaller hoses that go into the top of the tank. It appears when tracing down the lines on two other trucks with expansion tanks that one line goes before the thermostat and the other goes after the thermostat (upper radiator hose). Just wanting to double check being my pickup only has one small line into the top of the radiator and google searches have basically been geared towards automotive systems.

Valve lash question. This engine has the dynatard so it has the hydraulic exhaust valve lash adjuster. Book say you need a special tool to adjust this. When I adjusted the lash back when the head was rebuilt, I just made sure I was pressing down on the adjuster as I was taking my measurement. Is there a different/better way I should be doing this or just making sure the adjuster has downward pressure on it while taking the measurement work?

Sanitation engineer

I am definitely keeping all my old parts. It's kinda a thing with me that the wife doesn't understand. And I definitely agree that it is a brotherhood. I drove truck western states for 15 years before I took over full time my dad's garbage trk business and his trucks. Started helping him 63 yrs ago and as much as I could when I was OTR. Took over full time when he got off the trk at 83 yrs old and been doing it now for 30 yrs.