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That turbo should be putting out in excess of what you need to achieve good boost In my opinion ya need to leak check the whole system to the boost your expecting to run , We have an adapter to put into the  After cooler on the turbo side and pressure up the whole system heads and all  ya need to bar the engine around a bit to get the valves in the right spot to pressure it up   or pull the rockers to close the valves .but its the ultimate way to ensure you have no leaks! Stock coolers tend to crack on the hot side top front! There has been instances where boost can be dumped out the Air drier Depending on how you gave the inlet of the compressor plumbed!!

This can happen on the v8 as well but you would likely hear it unless your running straight pipes!

Do you have a pyro plumbed in what temps are you seeing?

It is a large solenoid beside the wiper motor that powers the cab accessories including the computers.

Did you replace this sol???? Key to this is next time it happens check to see if the heater is blowing  if the heater motor is not working the  relay acc solenoid under the dash is toast its under the ash tray to of dash!

1 hour ago, Back In Black Pulling said:

I take it you have the stock air cooler ? Should be plenty big for what your doing.

Have similar prob , driving down road get steady 50psi ,hook to the sled and flutters between 50 n 60 , trying different air cooler . Martins told me they had same prob on 1st truck they built,

I had no problem getting 39 psi with stock parts working the truck with under hood air cleaner .

Is that pump from that engine ? is  timing set for that pump ? Had different timing settings.

Wow Im surprised you not having issues with that volume of air going thru that filter I've seen that rubber elbow collapse on the single under hood style with a moderately cranked engine  33 psi boost stock turbo! how ever that may have been a washed filter not great for use with a high volume situation ! The timing idea is a possible cause however the engine has been timed from 17 to 24 for different years and horse power ratings.I have had them not run correctly  timed to the number stamped on the pump !  IE: at 17 stamped on the pump  very retarded smokey bump it to 19 or 22 OK .!  In reply to the original poster, as mentioned  you might bump it beyond the pump setting and see if it steps up the game a bit!

Check for boost leaks!

are running dual airccleaners?

doubt the under hood single will handle the air you need to have well

Yup what he said change it

are you seeing smoke under load? If not check the throttle linkage make sure it's going full on and your getting full stroke 30 is stock boost 

They kept only  few select things which they charge the the nose for , the mack diffs and the tranys, and some suspension stuf the rest is rebadged Volvo trash ,any of the well engineered mack ideas were tossed to the side of the road and buried.

What type of clutch?eaton pull clutch? 14 inch 15 inch?if you need help please post clearly what your working on?set the clutch linkage so you got a bit of clutch brake first and then adjust the internal ring so you got 1/2 to 9/16ths space between the throwbearing and the brake! If it's Eaton

Is there any way you can build a test gauge to test fuel pressure needs at least  60 psi or better  Under load to pull decent run a temp line into the cab with 1/4 plastic line!

also have some one check the ambient air temp sensor if its running an odd number the computer may be being duped into thinking there isint enough air to burn the fuel properly!so its holding back!

On 4/22/2017 at 6:05 PM, 07cl733 said:

Yes. I built a tool with a wheel valve stem and gauge out of pvc pipe. I tested from the turbo to the intake manifold. I believe that even if it were leaking boost a 5+ pound loss would cause very poor fuel mileage, lots of smoke and high exhaust gas temps.

On 4/22/2017 at 6:05 PM, 07cl733 said:

Yes. I built a tool with a wheel valve stem and gauge out of pvc pipe. I tested from the turbo to the intake manifold. I believe that even if it were leaking boost a 5+ pound loss would cause very poor fuel mileage, lots of smoke and high exhaust gas temps.

Correct?

On 4/25/2017 at 5:05 AM, j hancock said:

Never worked on one but the 1988 Mack Midliner brochure indicates it is a wet sleeve.

Wet Sleeve for sure!

On 4/24/2017 at 1:56 PM, lakewood said:

Well the tow truck just pulled my truck put of my driveway. We will see b what the problem is and I will let you guys know. Thank you all for your input and I must say this is by far the best trucking community one the Web. Thanks again guys!

Yup keep us posted thats what makes it better here!

So this is the the truck that you have been having the pulling issues with?

Your posts are rather Vague Bro ! You need to provide info here if you want help! Check the air cleaner  take the inlet off the turbo and check the wheel and shaft for movement if these trucks are new to you you may have the wrong muffler on or the muffler could be falling apart inside!Are the engines mechanical or are they electronic!

Engine brake stuck on?

22 hours ago, theakerstwo said:

A KT in a dump truck is too heavy for around here.

 

yup with out fuel  legal with fuel not so much!

On 4/18/2017 at 7:57 AM, kscarbel2 said:

BC, I myself am still trying to interpret the two videos, and guess who their target audience is.

Kev, they showed a bunch of stupid people. That must be the target market! OH WAIT! They are promoting a Volvo! Kind goes without saying.

What horse power are these units!? you could be having problems with fuel pressure  or the timing advance if these a electric engines!

OR install and after market gauge and plumb in directly to the intake manifold !

Yup that will work gauge will be hose not sensor!

You likly have a boost leak/ lack of air most times causes poor fuel milage and low power

OR install and after market gauge and plumb in directly to the intake manifold !

Like suggested you should have 30- 36  psi if every thing is tight *( no boost leake ) ect try running in cruise and see if this changes your values at all you may have a throttle pedal issue 

18 hours ago, ndvaughn said:

Would the truck run fine if the lift pump was weak? The truck seems to run excellent, no smoking or missing, just no power. I'm not sure on exhaust gas temps cause i don't have a guage for that. Engine temp is normal, and all filters have been changed. Is there an easy way to check for a boost leak? 

yes!  you would not notice  a miss it would just be doggy with low fuel pressure I Check the fuel pressure  change out the fuel filters It can be the pedal how ever not often ( to check that use the cruise buttons!) The other hold out can be the torque limit switch on the trans the wires may be rubbed and shorted together or a faulty switch this will cut the boost in Half so the ECU will not see anything as a problem! If you have no boost gauge GET one! it will tell you allot!

Newer clutches have two zerks onr in the middle one at 4 oclock!

12 speed