ambac pump 8050 problem/?..I think?

OK, sorry long post. This 8050 has been giving us heating problems for 3 years. I've posted here before and even thought the problem solved. We've done everytihing, rad recored, foam, water pump, oil cooler cleaned and tractor was still getting hot under a load. The tractor just seemed sluggish, runs, starts and pulls OK, but just didn't have the pep or power it should. The engine front cover was remmoved last winter to fix leaks.  The crank pully dimples are in line and the inj. pump is in time at 19 degrees btc. Pump was rebuilt in about 2008. OK, here we go, my mechanic is as good as it gets, former AC mechanic, hes's been working with me to find the problem. I ask him if there is a way to check the timing, he shows up with his diesel timing light. ( I didn't even know such a thing existed.) He hooked up to #6. At 900 rpm's it was actually only at 16 degrees, but steady. At 1800 rpm's, the mark would move from 16 degrees to where the the mark was so far down it was barely visible with the light and erratic, moving up down, dissappearing, back up to 23 degrees and all over. The tractor did not sound like it was laboring or missing or knocking or running all that poorly, tried # 1 and same result.  Mechanic starts talking about the advanced timing inside the pump, I know very little about the workings of an injection pump. He said he wasn't sure how or why the timing could be so erratic. Not even sure if the rebuilders have a way to test or check the oil driven advance system. Any input is appreciated, will a pump rebuid fix this or where do I go from here? If you want you can pm me or post here. Thanks.

The "intravance" relies on engine oil pressure to function properly. First thing to do is make sure you have at least 50 psi in the line to the injection pump.  The erratic movements from the light can be poor connection at the line. Most lights I've seen or have, the advance can be adjusted on the light to bring the two marks together, then the number of degrees of advance can be read in the digital display. With a diesel timing light, the signal gets confused as the rpms go up. This does sound like you have intravance problems in the pump by the symptoms you give. 

The inj pump could be not advancing it as far as it's supposed to, but it could be because your oil pressure may be too low, or just too low at the injection pump. Yes, running with late timing will make it labor, and thus overheat. 

that should be fine. Just be sure the pump is getting that oil pressure also. 

Inline pump swap time! Lol