What are some signs of low compression in a diesel.
The motor runs its best when its first cranked in the morning and becomes completly gutless after it has run for a few hours. My thoughts were low compression but Ive had some tell me low compression would do the opposite...run terrible when cold and get better when its warm...so which is it?

 

what oil you running in it? filters been changed?

 

White smoke, hard starting, excessive breather tube gasses/oil dripping from tube.

With the symptoms you describe, I would change fuel filters, check fuel system air leak, check the sock in the fuel tank.

 

i have none of the signs above. i have one at 250. 5 have 300 which is about 100 pounds low. truck starts fine down to about 18 without any help. i submit that sometimes a diesel is just a different breed of cat. not trying to hyjack just a personal observation.

 

Have a look at your IAT and MAP sensors.

 

Jughead:

250# of compression sounds pretty low to me.

I thought a healthy 5.9 was more like in the 450-500# range?

(Sorry just by memory)

I think you should find a service manual and look up what minimum compression numbers should be.