theakerstwo

To help out these guys that are helping you, you may get some one to turn the ign. on and off while you get up close and listen untill you find out if it is inside or out side then once you know that get back on here and tell us but i have found it is hard to tell what the problem is unless you are there and you are there so if i was you and can hear the leak then put your hand in there and start to pull and tough and rub around things untill you hear a change and now you know where it is a little now look with a good light for a oily spot where air may be leaking becuse some times there is a little oil in the air and it is left on the leaking spot and now dirt gets mix on that and it makes a dirty spot. I am not sure but i think you said it leaks with key on but do the engine need be runing? glenn

You are right that is a 50s mack engine and that is a 500 luberfiner bypass oil filter and you could not put a full flow on that engine and i remeber the switzer water cooled turbo and i dont remeber if they came with a oil cooler. many people put turbos on them and did not i guess put a oil cooler on them but when i think about it it did not have a full flow oil filter then you would not have any oil line to care the oil to the oil cooler because the 500 luber finer filter only used #6 oil lines . glenn

I dont know what kind or what year truck you got but let me play like it is a late model so when ign. is on it may be a air fan problem.more infro will help alot these other guys may know what you have but i domt glenn

The APE3 is the model of pump but for caibration you will need the other # and I think it is on the governor and a dealer or pump shop can tell you about that because 300 can take different pumps. glenn

Dont even drain the coolant untill you have pulled the pan and found the leak but some times you cant find it then with many hourn of checking then you can tar into it and start hopeing or guessing but as old as that engine is it could have a cavitated block behind a sleeve and may be hard to find but I have been in them for a simple inframe and have antifrezze drope on me from between the block and sleeve and then put sleeve and find a pin hole in block which then have a sleeve put in it to bring back to standard but have aways found the holes at the bootom of the water.Could be a oil cooler but should have oil in coolant. can be a injector sleeve leaking at the bottom into the clyinder when shut down but then you should have compression in radiator.glenn

And about theaair dryer the old one was a ad9 bendix and was good dier but all trucks use the the small light weight and it will work as good as old one but cost more be buy byt lighterin weight. glenn

Sounds like the parking brake vavle is wrong so check when there is no air on system and see if the vavle is spring loaded out that would be the right vavle and there is another vavle that looks alike but is not sping loaded.Also the later trucks will not set the park brakes untill as low as 30psi and when I worked at freighliner we had many times when drivers though they should set at 65psi like old time systems and we was have trouble exsplainig to then so I pulled it out of the sevice manuel and made copies for all and that problem when away. glenn

we may be able to help but need to know some info like what engine and what year and does the jakes work good when they do come on and by that i mean is it a electric or mechanicecal problem if it never holds goog then it may be under the covers and then you can gather more info from that glenn

To id the model look for a number that starts with a END on the block casting on right front that the injection pump is bolted to at the round part at the top.It will not be a cast number but a stamp number and if out of a cag over it could be at rear of engine on block but that would be a old engine. I will look at tat cadt number in the morning and see what is tells me. glenn

No heating or welding can be used on a steer spindle butr ok on a drive. If you would magiflux a good spindle with no damage you would find cracks on a large number of spindles and who would want a crack spindle on there steer? The steer spindle can be changed but if it is on drive then the axle doctor can cut and put a new end on the axle to get out of changing the axle housing. If is a truck for a toy then I would clean up where the wear is where the brearing will slid back all the way and then put it back together and see if it leaks again. glenn

My addvice is take it back thet may need the practice glenn

It may have a barrel and plunger sticking but any way it needs pulled and put on a test stand. glenn

It is better to change rear ratio's to keep the drive line speed dowm because that truck was spec'ed with a certain lenth drive line for a give rpm and gear ratio and when you speed the drive line up to much you may have some problems and I know the cowboys will tell you dont worry but I have seen it done many times with everlast problems of virbraions and you can blance drive line and if they are too long for the speed then the lease thing with cause then to loosen yoke nuts and the you have problems with bearings and ujoints going down and with eaton trans then you will have snyonizer pins breaking and the list goes on.glenn

You need to drive it with a pryometer now or overhaul later glenn

if you have jake brakes it is simple to slow engine down to shift. glenn

another way to turn any engine is to jack up one wheel and put trans in hi gear and bumb the wheel over by hand with a bumbing motion and if it is hard to turn you may need some one to watch the what ever.I have did it for years even runing over head you turn a litte and walk up and look and turn some moore till you got it and that way you dont have to weight on some one to come over and help. glenn

If I remember right the exhaust port bolt pattern is the same but you are going backwards in technology and probley would hurt in power and every thing else because 2 is not better than 1 in some cases. The twin turbo was started in about 1966 and if that was good I think 1 would not replaced it. glenn

The roosamaster pump has a gear pump on the end that can go bad and you will have to send the injector pump to a rebuild shop to tesr it. glenn

There is many things that can cause low oil pressure and I can tell you that those probles is not easy to find some times. Had did you check the oil pump wear? That has to be done like to book says and you can look at any thing to check it .It has to be measured for wear and the rod and main bearing have to be good and the right size and the crank and cam can be worn below specs and the oil filter needs to be clean and the oil regulator can cause a problem and fuel or gas in the oil can cause a problem and the rockers might but you dont see much troblem with the rocker with rear. And always check the oil pick up tube for cracks. hope that helps. glenn The reason I said any thing about the crank wear is because I know of a dt466 that give a lot a trouble with low oil pressure after the crank was ground .It took about 2 years to find and we checked the bearing clearances with plasticgage and found that the crank was grounded to much on one journel

I remember the roosa master pump on mack engines and that was in 1965 and 1966 but was on r models but could have been used on b models also they were had to start if they did not have a electric fuel pump put on to push fuel to the injection pump.they could not have been much good I remember and have worked on the psj and psm pumps that the end664 used and it was a short lived pump glenn

You are right about the head bolts I worked for a mack dealership when that engine came out and it is ok to turbo them but do not set up the fuel because it has a hi copression piston and it is still hard on head gaskets .I would be ok to set up fuel if the truck does not have to work but just play. glenn

Make sure there is no slack in the rear brg. or yoke before you choose to not repair because if a brg. is going bad you could hurt trans and those parts are too hard to find. Glenn Akers

I would never set the fuel up on that engine if it is a truck to work ever day but if you are playing with it and it is yours that would be ok.The top rpm is not 1750 but that is were it is at at peak torqe and that is were the governor starts to cut back. You need to check full throdle and make sure you are pushing the lever all the way and you do that by not starting the engine and get some one to mash the pedal down and you go around and see if you can move the lever any more and if you cant then you are geting full throdle but there is all lot of things to check before you start to turn screws. hope this helps glenn

I have seen many frames straightened and no problem if did right but you cant let just any one that has a torch do it. glenn

I think that I remember the engine # on old cummins were at the middle or fromt of the block just below the head and a 8########.I have not looked at one in 10 years but I thimk they were there so look and see and I have the cummins quick serve web site at home if I can find my password Glenn