I just bought a 98 1/2 3500 with a 5.9 cummins and a 5 speed standard (150,000 mi). The truck starts fine cold, and runs great, shut it off after running it for 30 min, wait 5 min and it starts fine, wait 10 min and it still starts fine, but wait 30 min and it wont start without ether. Another point is under heavy hauling I am losing oil out thr breather tube. help! The local dealer says these engines should be rebuilt every 100 thousand miles. I find that hard to believe.

 

That guy is smoking the gunja...

 

I'll second that


anyway, your lift pump is probably looseing prime, need to change it out before you kill the VP44 injector pump which is expensive.

second, I would pull the valve cover off and re-lash the valves, then I would pull the radiator off and have the thing rodded out to remove corrosion. sounds like the engine is getting a bit warm.