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I would head in the direction you have been pointed, T in a fuel preasure gauge at the fuel pump and check preasure there full load it should not drop below 20 psi full load .If it does check all the lines and if they are clear check to see the drain back valve spring is not broken,I'm kinda working blind here and am assuming its not e7 or vmack. transplant.

I have seen this many times on these units most of them boiled down to the air drier leaking internally! remove the small air line at the air drier install a temporary guage on the end and watch the guage if the gauge stays put once the compressor unloads you have an air drier problem! replace the air drier again.

Packer has a good thought there! I have seen the solnoids come loose check em while doing the valve set !(Which by the way will set the dynatard as well its built in to the rocker!)Also you can cheat some on this setting to get better performance set your exhast to 22 or real tight to 23!A little bit goes along way. 0

Crank and push rod???? dosent add up in my mind! or crank and conrod please clarify. you pull Engine out the crank out?? I'd be carefull!

I don't have all of your answers But heres a couple If the engine is indeed a 375 hp then it should be (painted silver and have a 12 speed behind it.) -2150 to 2300 rpm is fine perfer 2150 loaded note if the no load rpm goes adove the 2100 say closer to 2500 then it is 325 hp engine The valve set wil be intake 16 exhast 24 for either. -Boost sume where around 15- 20 psi'!(Guessing on this one) -pyro 1000-1150 -Dynatard is always weak get use to it! -oil psi 30-40 idle 650 rpms -oil recomend 15/40 -30 w ok -turbo depending on how hard it was worked ,replacing the turbo not a bad idea depending on what your plans are to do with the truck. -Bearings is a work thing ,if it has 10 to 15000 hours on the clock not ,a bad idea to roll in NEW bearings ! - axle it may have been born with that axle depending on application crane dump ect. The steering end play thing is not somthing I put in the memory bank sorry! good luck with your unit!

Did ya get the trans working yet?

Yes !Give them the year ,model and last 6 digits of the vin there may be somthing that can be done. They can at least claifiy things for ya! http://www.macktrucks.com/default.aspx?pageid=53 Do you guys need 405 hosepower? Maybe derating the engine will be an option? It has become most important to spec a truck for a job these days Other wise you end up with problems like this! In other words if you buy 405 hp you had better be using it 80 percent of the time!

Brother ,I'm sorry I can't help,We have had very few regen problems Have you tried the one call people?They may be able to prescribe somthing! 1-800-866-1177

It is supos to move against the springs there should be no space between the springs at all no free movement.If it looks rusty or worn at all or if in doubt change it, not that expensive there are two types a three hole and a two hole. also if you got air ride cab it makes things way worse!Don't spend a dime on anything else till you try a new lever.It may surpriz ya.

How was your idle time?

Also check the throtle lever to see if the springs on it are tight if the springs are lose the throtle will jump about and so will the rpms in light to mid throtle.To check hold the throtle at half by hand and grab on to the shaft portion where it clamps on and try to move the shaft part if it moves and you were holding the rod steady the lever needs replacing.

The inversion valves replaced the regs and the quick release I beleive, there is only one reg now you'll get it figured!

Its called an inversion valve (sort of a quick release.)Really its a an air operated on/ off valve. There should be two of them. Anyway you can delete the line to the engine if you feel the need. it somtimes can cause greif with power.plug everything thou.bro The lid is not going to fix it's self ya need to get it off and verify what is going on.Having said that thou, somthing that gets negleted on 12 speeds is the air filter Does it have one?Should be on the rh counter shaft cover. If so get a new one.Drain the air before you change it. Check out the diagram left at the first part of your post.

Yes Correct.Mark the lines when you take em off .

Where Glen is heading with his coment is if it goes forward to the intake it is the torque limit line! if that line is causing issues simply cap it off and plug the t fitting on the trans.

I have seen an r700 with ntc cummins in it Our army had one or 2 with this oddball spec behind it was a fuller 15 speed I beleive.Leave it up to our guys to order an oddball combo . If you going to buy an all mack driveline.Not sure if it were a 766 prefix thou.Quite Likey A modern day mack cl would be cl733 real mack power 713.

I googled this http://www.dieselpowermag.com/news/0707dp_...e/photo_01.html The 237 dosent have the after cooler.

Number 20 is the revese piston. Read carfully what I wrote last ! Remove the rear line on the rev cyl with the air shift selector in rev ,check to besure there is no air escaping the cyl thru the fitting or coming down that line.if there is air on the line it may be the shift knob.

Bro ,ID be checking the plumbing as well! When reverse is selected you should have air at the forward port of the reverse cyl No air to the rear port of that cyl (if you remove that rear line there should be no air coming from or going to it! if itscoming from it its leaking inside and needs orings!)Also when reverse is selected you will have air to both sides of the spliter cyl holding the split in neutral.

The adjusting nut that you are refering to was deleted in later years this likly being one of them!If the split doesent center its self you have to shim the spring!When you get to the part in the rebiuld routine where you apply equal air preasure to both sides of the split hopfully you will have no problems. Most times its OK.Also in the tips Rob gave to ya if the shift fork bolts were not tight when you go to loosen them THAT can be a 90% posability of your problem!

No you have to remove the whole module! (Shiftlid) its a breeze on tht model of truck You can have it out of there in less than an hour!If your hving an intemitant revers problem still it maybe the larger cyl causing the problem there is a lock out pin in the lid,If the spliter does not make center for any reason the reverse air shift will be locked out! When you get the lid off check to see that the set bolts are tight on the shift yokes in the lid that is the first check of the day! If one or both are loose remove and apply locktight and re assemble. If not remove the cover of the big piston and check for any rust or broken snap ring.

E7 no side covers is the give away. And mech pumps were offered on lower hp a few years beyond e pumps.

That is compound low! reverse is on the rear shift cyl that looks the same size as that one back shift lid.There is a switch on the dash for that one.

More stuff to try! asuming it is vmac 1 or 2 Not eteck and IF it happens any old time ,also asuming you have no fault light on ,In my opinion you need to have the fuel pump plug repined take it to a dealer and have them put new pins on the fuel pump conector.this very often will cure the problem. next (IF) the problem happens when the engine gets warm Get a bucket of water and pour it over the back part of the fuel pump then try start the the unit if it starts the fuel pump needs to come off and needs internal repairs try these two things first the water trick is the odvious cheaper of the two (IF) your symtom is as discribed. Note This info is provided from the Mack book of hard knocks and is not writen in any manual on the face of the planet to the best of my knoledge..