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A Maxidyne engine will hold on right down to 800 rpms Its not the best thing for em but they generate good power even below 1000 rpm! It is real amazing! Huge power band As for the R never seen one sorry! Might be as stated Restricted upper rpm duno!

Make sure the throttle lever has no wear at the throttle shaft If the lever internal springs are worn it will cause the idle to be erratic . if the lever is good then the governor is worn and heeds to be removed and repaired! OR just live with it!

how's the fuel pressure ? if it has unit pumps it needs 70 psi to run decent, if it has vmac 2 it needs 15 psi min to run right low fuel pressure fuel transfer pump failing or sum bad fuel lines coming to and from the pump also fuel drainback valve issue

The fixed shift rail can break and also cause this !u need to lift the lid off and look! also a loose lock bolt on the air shift could be an issue

possibly Injector Cups

25- 30 psi

Codes ????

Or Loose wheel bearings

I'm a bolt and pry bar guy as well the kent tool only comes out when it got a stuck one!

Its possible the boost pop off valve has stuck open ! its the brass fitting hose and 1 inch steel pipe that lead back to the exhast pipe from the inlet and egr mixer tube!

HELLO???? This is a Mack forum bleeding the air from the cable is a little tough! that assist is constant feed . ARE you driving a volvo or a mack?On A volvo hydralic Clutch you sumtimes have to stand the slave cyl upon its end to bleed em!

Yup keep an eye on both ends the coolant and the trans I just ran across the beginings of one of these the other day! Fortuantly didnt wreck the trans yet! we ussually get em after the damage is done!

injection lines yada yada you need a donor engine to do this it would be too pricy otherwise

Make sure you observe the width of the roller on the pump you take off if its a wide roller your OK if the roller is a narrow roller you can cause your self problems Compare the pump your putting in to the pump your taking off! Wide on narrow is ok narrow to wide is a problem.

These were notorious for loose valve seats and worn valve guides! listen carfully after the engine is warmed up, when shuting it down you may hear a pop pop coming from the head area!That is tipicly a valve seat.

You need to preasure test the Whole intake system for leaks ! I have seen intake gaskets blow a chunk out! cap off the hose at the turbo side of the charge air and put regulated shop air into the hole where the puff limiter reversing relay WAS and crank it to about 30 psi you will likly find a cracked cooler or intake gasket blown out! OR At idle run propane or ether around all of the intake system if ya hear and increase in RPM you have found your leak pay real close attention to the ends of the charge air core they tend to crack!

If you have steel rims check for a cracked inner wheel! (Usually) power divider problems are an fairly evenliy spaced clunk along time in between usually caused by missed matched tires.

Thanx for clearing that up Staxx I Kinda wondered about the bearing issue ,they we only did half a dozen trucks here and heard no more about it, as time went on the issue kind of faded!

Cover the jake heads with a rag and operate it manualy by pushing in on the center of the sol with the engine running see if you can get it to operate Observe how much if any oil is getting passed the slave pistons on the under side of the housings if there is lots the housing are likly the culpret this was a real comon problem with these,The oil line kit will likly be pricy as it consists of new jake heads and spacer plates and lines! ALL of the above helped but only marginally The pump and bearings helped the most and would be allot cheaper than the oil line kit in my opinion!There was a special bearing supplyed for sum engines which reduced the bering clerance from 3 thou to1 .5 thou if I recall correctly!Ya may want to check into this IF you can find a good oldtine parts guy Barry may remember this or have a buliten he can look up! and yes the plugs I spoke of are on the rocker shaft ends!If there is one missing you will only have one head operating! As for setting them up 21 thou in my opinion is counter productive you already have a shit brake and 21will make it worse, I have always set them at 15 (even with the updated screws) when you think about how it works the more gap you give it The less you open the valve the less effective the brake! The 21 set would open the valve 6 thou less! Again just an opinion and a bit of Trial and error experiance.Less the error part ! Also run power to the jakes with a jumper wire and see if you and make em work cold then hot!

Did make sure the plugs were in the ends of the rocker shafts??? it is quite common for them to pop out!

If you took the delivery valve out you need to snug the nut back down did you do this?If you are still having greif post a picture of the pump it my help us determine what your up against.I use a hose and blow thru it to time most of the time!

The sol is toward the front of the pump it has wire going to it with a screw on top.

Also the older pumps have a slip clutch on the pump cam ,if the clutch gets worn the engine can over speed if your simply going to governed rpm your golden, if its going over the governed speed be carful not to be stomping on the throtle as it reaches top rpm It may not come back down! Its possible its a sticky rack or simply a throtle cable / lever issue operate it at the pump and see what it does !

is the check engine light on on the dash? the timing advance solnoid is likly haywire!You could save your self the bucks of buying the sol by doing this I have found that replacing the solnoid Does not always fix the problem changing the timing will fix the problem for ever! I have had this happen I have ended up setting the timeing up to 10 degees its a farely big job because there is alot of stuff to move out of the way to get to the timing gear and you got to drain the coolant. but all in all its worth it!