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Not easily serviced by the average Joe ! If that what it is ! The other thought is a sticking EGR valve, Less common however a possibility! Turbo issues are most common ! as Tech mentioned High on the short list!

We use donaldson as a second line and sell them for those who don't want to spend the bucks on genuine Mack I have seen them come with threads not there ,However seen it happen once on the Mack filters too! Shit happens! Automation!

That is a possibility ! Should show up a low fuel pressure!

Splitting hairs! It’s a form of egr!

So Money pit here's a thought and some experiences for ya! One test that can be performed is to put 12 volts to the solenoid if the timing advances then the econovance is working and you may still have an electrical issue ! there is a spring inside the unit that can break and there are teflon piston rings that can wear and deteriorate !So in that sense the mech is correct ! IMPORTANT If the econovance is working correctly the engine should start and stumble and smoke blu white smoke till the oil pressure comes up once the oil pressure is up, the engine should clean up and run smooth! at that point the engine is running @ apporx 12 degrees advanced !Properly working the timing should increase with RPM up to 22/24 degrees depending on RPM ! sounds like yours is not working! I suggest you put 12V to the sol and see if it advances the timing you will hear the difference if its working if you don't hear a difference then the line across the front of the engine could be suspect change that Its Cheap! And available anywhere! then try the test again Manually if the issue is still there your likely going where they are sending you! If the issue goes away and you still have a problem with the wire from the harness connected then you got a wirring or ECU issue ! SO A possible work around would be to cap that line off to the econovance and set the base timing from where it is now roughly ( 6-8 degees) to 19 t0 20 degrees this may get you to work with out spending a big bag of money on parts ! Because in my Opinion the econocance was installed as More of an emissions issue! not that much of an economy thing! (And that there is JUST AN OPINION!) not a fact!

Have you replaced the line to the econovance, they can deteriorate overtime!

Yup Hide And go Seek!

Yup I agree with Tech ! Also Its unfortunate but in that era is the year prior to Egr They were struggling to meet emissions Targets And to do so they were being stingy with fuel ! We had a lot of power complains back then, we even dynoed 460s that were putting barely 360 to the ground And they would NOT Fix it! We live in steep country here and need the ponys to get things up and down mountain sides anything less than 500 hp is inadequate!The V8 or Mp ten was the answer for this However they saw fit to remove these from the line up!

E7 no egr E7 aset and AI are both egr engine’s

long as it cleans up when pulling I believe you'll be ok in that department! i'm Thinking the same as milkman Is likely the rad or the fan hub by what you discribe!

The computer Will likly show a bad pump not the injector! u still may have a bad pump if you changed an injector! just sayin

In your case remove the valve cover and check for broken rocker shaft bolts! Just my opinion! the new engines had an issue in this department !

Yup Nice install! 285 or 300 as stated!

To Late now its Spilt Milk! The Gas companies here where I live advertise on tV all the time ! CALL BEFORE YOU DIG ! I think that applies Here!

Like everything else ! mother Volvo screwed up the Heavy haul now the light haul ! Middle ground is all that's left! Oh well I predicted the mack Brand would RIP after the tenth year And we still going ! I was wrong ! even thou the mack cab is really all that's left, the brand is still here , However shallow it may be! Might see another ten years who knows?Once the cab changes that will be the END! Parts are drying up for the old stuff and even the newer stuff!Tough to predict the End BUT Its coming unless Scania or some one buys in ! Highly unlikely as The Volvo influence Is Deeply ingrained From the parts system down or up whichever way you want to look at it! 😡

the problem is likely inside the bell housing

Its likley the clutch actuator is leaking down and is not operating the clutch properly Either a leaking hose or or the bellows has a hole!either way its pricey! and you likey have to take it to a dealer!

Yup remember everybody is saddled with the same rubbish to add on to meet the emissions , Must be some other stigma! ? Maybe the VW People Are Evil !?🤪

Also the supply pumps can fail ( Fairly common) is your oil level staying normal or rising !

new style lifters are of better design the original lifter had the hard surface silver soldered on the new style seem to be one piece these never or rarely fail !

Check your oil pump I’d replace all the lifters

We access thru our dealer portal you may not have access to that on your set up not sure

so likely the 285 hp then

If you have a mack logon at your location you can log on and go to this section ! Case based reasoning ! They have collected all of the field repairs and fixes and compiled them for guys to shoot for when having issues with this and other stuff Its one of the few things that they did right with the program ! as its not all theory Its fact base repairs Done by real people not dreamed up by someone whom has never turned a wrench!

My opinion you have a 285?