RS Disposal

2 hours ago, The Heinz said:

What's your fuel tank look like? You could have gotten some bad fuel or something if there's residue in the tank. We've seen it happen locally around here; an entire fleet was having some fuel issues (all newer trucks), and it turned out to be a batch of bad fuel at the local fuel station all their drivers were going. 

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

2 hours ago, fjh said:

Give it a try definitely worth replacing them ! The pump is Ambac worth keeping an ear on too the over run clutch can be an issue! Snap the throttle and listen for it jumping to governed rpm if it travels beyond the governed by more than 50 you may need to have the drive hub serviced!

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

On 11/20/2025 at 8:15 AM, Full Floater said:

Any chance that it's sucking air into the fuel system, or fuel restriction?  

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

On 11/19/2025 at 3:15 PM, D-Day said:

There should be a tag riveted to the side of the pump that will tell you what pump you have and the pump number

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

2 hours ago, fjh said:

can you identify the fuel pump for us! Robert bosch or ABAC?

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

24 minutes ago, Geoff Weeks said:

Budd is slang for stud pilot, that may be confusing you.

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

On 7/24/2024 at 3:54 AM, mrsmackpaul said:

I wonder if a lining has come loose on a shoe, is in the rivits have loosened 

 

Paul

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

On 7/24/2024 at 6:58 AM, fjh said:

try greasing the cams and see if the situation changes ! dust is quite likely

1

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

On 7/23/2024 at 7:26 PM, Geoff Weeks said:

450 to 500 ft lbs on inner and outer stud pilot nuts.

Brake noise is often dirt/ dust.

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 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

Just now, mechohaulic said:

hopefully the brass hammer tapping was being done in the center by bolt hole NOT outer edge 

it was definitely in the center of the dampener.  put an impact socket into the center of the dampener where the bolt goes so the force was directly in the center.  With the heating of the dampener with the heat gun before it didn't take much to get the dampener on far enough to engage the bolt

12 hours ago, mechohaulic said:

no reason to apologize "for all the questions" . knowledge isn't achieved with out questions. also best to ask then to screw up , resulting in lost $$$$

This forum for me has been a godsend.  Everybody has been so helpful in my quest and with my learning curve since my breakdown last fall that started my journey.  I know there must be some older mechanics in my area who would know this stuff, but when I was first making inquiries into having a shop do the repair the attitude I got was that nobody really wanted to work on a 40 yr old truck.  Probably because it wasn't sitting in their shop taking up space and knowing that sourcing some parts might be time consuming

12 hours ago, mechohaulic said:

13 min 250 oil ??? new tech . another first  for this  ole man ,   emery cloth -clean both mating surfaces . install dry ..challenge of the day was lining up the mounting holes. they are off set so damper goes on only one way for balancer timing marks, follow up on rear crank seal ==was it going to be changed or this is in frame??

this repair is in frame

I was able to get dampener on by using emery cloth to make sure everything was clean and a heat gun.  Was able to get it on far enough with some light tapping with a brass hammer far enough for the bolt to engage the threads and pull it on the rest of the way

Just now, fjh said:

Torch and a heat gun ! I have put these on cold !

A heat gun I do have,  Thanks

Book says to heat vibration dampener for 13 minute in 250 degree oil.  That I do not have access to. Is there something a little simple for me to do?

And I agree about the camshaft gear.  My son said he might of been able to get a small oven that they use at his work to heat bearings for the big pumps his company rebuilds.

1 hour ago, fjh said:

Yup back it out when installed turn it in till it touches and back it out  half to one turn! Snug the jam nut and your done!

Thanks, I eventually found the adjustment in the service manual.  Guess I'm getting tired. Been up since 11 pm last nite

Sorry about all the questions, but should I mess with the end play adjustment on the timing cover.  have yet to find in the service manual where this is addressed.  Maybe I'm just blind  LOL