miro

Starter may have a thermal protection switch that is defective, try changing starter

Sounds like you have a bad primer (hand) pump

I doubt a coolant filter will help your problem. There is no filter media in them. They contain DCA and slowly add that to the coolant. You can get the same affect by testing the DCA, with test strips, each service with test strips and topping it up. Don't think that just dumping it in will fix the problem. too much is as bad as not enough.

If you're torquing them with a 1ïnch gun and then a six ft bar, you're stretching the studs. You only need 280 ft lbs of torque on a 3/4 stud

Check your motor mounts and crossmembers. If these break the frame can flex and cause that kind of problem

I think you'll find most people in North America, buy exchange transmissions and diffs, warrenty and availability are main considerations

Check Toe and Wheel alignment

I agree with 39 Baby Mack check the over center spring on the throttle lever

Actually I remember Mack had a kit to install shocks on the front drive axle. The lower bracket bolted to the back to pocket rubber bolts and the top one was one of the trunnion bolts

You said it needed a clutch. If this has the push style clutch you might not have to change it. Mack used to put L shaped spacers between the pressure plate and flywheel, held down by the bolts. If you have this all you have to do is one by one remove those spacers and re-tighten the pressure plate.Hang on to those spacers you'll need them if ever you do need to put in a new clutch. Also a word of warning those old clutches and brake blocks are made of asbestos, do not breathe the dust!

Maybe a dumb question, but how do you work on the engine? Doesn't look like the cab can tilt.

Check for a bad ground from engine

I am looking for an inexpensive computer reader, that would read mileage and or hours, and would work on any modern system. It does not need to do any diagnostics or tests. I have Googled it and saw some Chinese units for about $170 dollars, anybody have any experiance with them

Put some ultraviolet die in the cooling system, run it for a day and check the engine with a blacklight. Be sure to check the bottom of the air dryer and the intake of the compressor (if it is fed from the engine intake) and the engine oil itself( Not very likely if its not milky)

How old is the truck? Does it have Positive ground?