Lmackattack

All I can tell you is dont get the epa involved or go to any scrap yard who might get them involved. Your best bet is to let them drain as long as possible so you reduce the oily sludge mess. sheer them up into smaller chunks if possible and then crush them flat so they don't look like a tank. Put them in mix scrap loads. When I do it this way the yards never even know because it just looks like normal scrap. If they are heavy with sludge in the bottom. fill it plenty with exhaust fumes from a truck before using a partner saw or plasma cutter to make a large doorway into the tank. This will remove oxygen inside and reduce its chance on flashing over. Once you have a doorway you can shovel the slop into buckets. And the tank is now safe to cut with a torch You just need to dismantle them so they don't resemble a tank and they pose no safety issues.

You have what many mack guys call a low rpm engine. It is set to 1700 in attempt to gain fuel economy. The trucks built with these engines would l have had different rear gearing to compensate for the reduced rpm. You will need the pump recalibrated to 2100 rpm specs to gain more rpm. Not sure if you can do it while its still on the truck but I know it can be adjusted.

.If you think the coolant is pressurized. You can bring a fairly cheap co2 tester with you. You will want the truck to run for a bit to see if combustion gasses are entering the coolant. RELD Head Gasket Tester Kit Combustion Leak Detector for 50 Tests https://a.co/d/4va7zaw

This was the cap end of one of the rods. Looks like it's a P1 bearing

On my b model with budd wheels. They are standard lug nuts with right and left hand threads depending on what side of the truck they are on

Many say that. But it just doesn't build pressure like any diesel I have driven. I'm used to seeing it snap from 30 psi hot idle to 60+ psi as soon as the throttle is touched. This thing has 35 psi at 1200rpm. That's when she's making all her torque !

I did not. I was hoping the bad plunger I found was the issue. Talking with others it seams .003 is the upper limit for good rod clearance. General consensus is I should just roll in a standard set of rods and mains next to see if it cures my concern. If that don't fix it it's probably worn auxiliary shaft or cam bearings. I may pull the valve covers just to see how oil flow up there is.

Pulled 2 rod caps down today. The bearings were spotless. If im reading the bearing numbers right they are noted as a P1 / standard size. I plastigauge them both. Got .003 clearance. Is that within spec? I shimmed the oil pump with new plunger and spring. Installed new plunger and spring in the upper and lower parts of the fuel pedestal. Put the pan back on and filled with oil. I Still have what I consider lower than usual oil pressure. Hot idle pressure is slightly better. Previous was 25psi now its 30psi. However i still have to spin it to 1600Rpm just to see 40psi. And at 2100rpm it is at 50psi. the oil pressure spec per my mack manual says 40-95 psi at governed 2100rpm every maxidyne I drove the oil pressure jumped to 50 right off idle and by 1200 it was pedded at 60-70psi all the way to 2100. This needle barely moves untill over 1200rpm then it slowly increases with rpm until high idle. Still scratching my head at this

So I dove in a little further. I removed the upper and lower plungers from the filter pedestal. The blackend plunger with wear was from the top of pedestal and was kinda stuck in there. I could push it in all the way in but about half way out it was binding. I had to use needle nose pliers to pull it out. The lower plunger is from the bottom of pedestal and came out with my finger. The 3rd pic shows both side by side. Both have the same 21A stamp on them so I assume are the same plunger but obviously one has the chrome worn off it. The plunger spring also had some caked on crap that was not metal but was hard like plastic. Not sure what it was but it was stuck in the spring. I hope to have replacement plungers/springs next week

That's what 2 people have said now that it looks like welding slag. I think it looks like block casting that may have flacked off. I definitely will be putting in a new spring and a shim washer to see if it helps pressure come up. Your right about most of these endt675/676 motors coming right up to 80psi on start up. This is lucky to see 60. I

When I bought the truck 15 years ago. It was running about 50psi at 2100rpm. It might hold that psi with clean fresh oil but not older oil with some fuel delution in it. I swapped in a new dash gauge 5 years ago and it read the same. The truck has really only had 3 oil changes since I have owned it and every time it had fresh oil it was a few psi higher. I have mobil 1 synthetic waiting to go back in now. I dropped the oil pan and pulled the presser relief today. Spring measured 3.46" . Plunger had a little wear on it but nothing I could feel with a fingernail. The picture makes it look worse than it is. Regardless I ordered a new spring and plunger. I did find a metal chunk in the pan stuck to the pick up tube. The tube did not have a screen on it like i thought it would have. It just was some grooves cut into the pipe. I forgot to grab a pic of the tube but will tomorrow. I may pull the pump to see if any metal went thry it. If anything to inspect the pump gears.

Maybe use smaller roller diameter to compensate?

That's a good suggestion. I'd suspect it's not because it reads 60 psi at cold start but it's worth looking into.

It's not horrible for a hobby truck but I'm use to seeing the 2v and 4v engines jump to 60psi right off idle. This engine oil psi is barely increasing off idle and It takes all of 2100 to reach 41 psi. I was surprised to see my copper readings so low. I was ready to roll in a new set but now I'm wondering if thats the issue

My 77 mack with 283 tipturbine has about 25psi warm idle and 42psi at warm high idle. Cold start is 60psi I feel the oil pressure is low for this engine. It's been like this for 10 years and want to try and correct it. I did an oil sample and results were normal for a hobby truck That idles more than ddriven.i thought I was going to see high copper values but they are normal. I will be replacing the plungers and springs in both the oil pump and filter pedistal. Is there a procedure to adjust the oil pump relief spring. Or is it just bolt in and go? Thank you