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The old adige ! It's hard to get good help these days! was never so prevalent as it is today! People that care are few and far between!

Bro this happend's lots at our place too! Difference thou is we don't got a tool budget if its something we run across we need we will build it if the tool looks to overly priced by the volvo /mack criminals! There are also things you can do on MP engines to find leaks that are NOT In the manual ! On an MP8 if you you got a squeal/ leak simply force a regen on it ,this will usually build enough pressure on the exhaust and intake side once its making the noise, run warm water over the manifold/turbo and egr cooler plumbing joints this usually will uncover what your looking for as a sound change when the water hits the effected area! Just shit you learn over the years you know how it goes!And usually its the school of hard Knocks that you learn from ! The above MP8 story there was learned late on a Saturday afternoon at going home time after a EGR Cooler change! 😡

yup any thing up to 40 psi depending on what your looking for!

You done Good!

jojo we built a setup for boost checking these engine two flat plates capping the exhaust and the inlet ! We also had to plug this valve off after testing it to see where it was blowing off at.remove it and put a pipe plug in its place then pressure up the exhaust and intake system to check it all for leaks this test was ultimate for leak checking Absolute coverage as far as leaks went!You can even check the turbo drain tube for blow by which was a fairly common issue on these and some AI turbos!

Not saying this is the problem however these engines are or should be equip with an over boost valve and tube ! That valve may be sticking open! Its the 1 inch tube on the back of the intake horn on the engine the tube attaches to the exhaust pipe! this valve is apparently set to lift off at 25 psi if it is sticking this could cause an intermittent boost scenario. see stax comment

Just to add a little to Joes advice all good suggestions! However! If the engine is not suffering from performance issues or throwing up engine codes other than an intermittent annoyance miss .I personally would not chase this! Only because I have done this before with no success . However if you do pursue it and you find success Please post it here! I believe it has something to do with programing ,the engine ecu is trying to make up for a cylinder imbalance in my opinion! Now that being said ! you could up root all the eups or the one you suspect and check the springs to be sure they are not broken do the swap if you want! but remember that the cal codes need to follow the eups as you swap them!

Yup Good call bro !Joey IS THE MAN!

10 psi

So before jumping to far ahead here the 7th injector is likley coolant cooled on that truck check that before condemning the thing! also the egr is controlled by the dpf on the egr tube if its polluted with coolant It will command the valve open if the cooler is restricted! Being deleted we don't know what they have done to this programing! Remove the egr hose front of the EGR cooler first cause its easy If it is soaked you have your answer ! Then check the injector, if the cooler is OK!

SWEET Looking unit! RDSX?

This here is the most odd post for me ! We have in our yard a fire truck converted into a food truck ! It is almost identical in spec! The engine in the unit we have had a leaky liner and took out the bearings by being run with water in the base a real shame The guy bought it for 15000 4 years ago if that gives you an idea for its worth! Unfortunately He put 15000 in grilles and cooking equipment into it then the motor createred !

I got to think you need to do the air in fuel test after the engine is warm I would lean to cups as you are thinking there( How ever) there can be other issues as mentioned sticking VGT when warm , EGR Valve commanded open due to low EGR Flow readings . This engine being deleted we have no idea what the program is doing in that area? Try unplugging the EGR valve and see if this changes your situation!

yup i must agree 38 psi is way to aggressive to much fuel ! Its Either tuned up or something is a miss in the governor! I have seen the fuel stops fall off on the ambac pumps which would cause this little engine to perform like a race car! A turned up e6 will self destruct in short order by breaking main bolts or cracking the block at Number 4-5 main if left like this! I Guess pulling the pump is highly recommended with that view on it!

Don't pull the pump till you check the easy and cheap, stuff puff limiter, make sure the tank vents arn't clogged ,,change them fuel filters as mentioned is it rob bosch or AMBAC?

Yup you have to by a new truck if you want a new practical connection!

Yup what he said! 😇 4:17 4:42 ratio? Check the gears set for wear! these ratios tend to pit out bad if you haul lots of weight! Also if the unit has a lateral torque rod to the frame check the bolts inside as stated ! the housings also tend to crack in that area when equipped with this torque rod! not too much a guy can do but pull the diff and weld it if this happens!

Good call Ony ! This comment applys To the newer vehicle's specially! The magic transmissions and after treatment crap needs dri air to operate correctly We see more failures to the 7th injector dowser modules attributed to water than almost any other failure on the after treatment setup ! and the stuff aint cheep!

Mike is the tach showing RPM? Just wonder if your chasing the wrong thing here Fuel transfer pump comes to mind! just saying!

The rocker arm assembly must be removed check them ALL! There is a special tool made to hold the slave While repairing it however you can get by with some aluminum soft jaws in a vice!

Mack pros got a point! To the un trained eye I the engine brake slaves would not be easily noticed! You claimed to of done a valve set did you adjust much on the 1-6 we usually catch this issue when doing a valve set It shows up as a real tight engine brake set on the offending cyls! Also it is possible you got some pin fretting or rotten wire on those two injectors causing the codes ! possibly unrelated to the noise! Just sayin

Also if you have clunks and you have steel bud wheels pull those wheels and look for broken rims!

Is the check engine light on? Is the suspension dumped? M Drive? Manual trans? You need to give info if you want answers!

Also bare in mind there are available oversized liners you need to watch for this When ordering parts ! the liners are etched with The part number the last digits ending P5 p10 ect being the oversized number! The liner should be a slide fit for the first 2/3 of the way down then a semi aggressive fit last 1/3!you may need a wooden block for the last little bit to seat them!

clean and dri shaft and plug reinstall with red locktight!