I have put together a couple of gassers and am in the process of rebuilding my 7.3 idi turbo. On the gassers I used stp on the bearings and coated the cylinder walls with oil and give the pistons a coat of oil before putting them in the block. Is there any difference when assembling diesels.

 

I don't think it makes any difference gas vs. diesel. I use trans fluid on the cylinders and regular motor oil on the bearings, unless the engine is going to sit a while before first fire-up, then I use vasoline on the bearings and squirt some fresh ATF in the cylinders before firing (spin the motor over with the spark plugs/injectors out when doing this).

 

Mix of 10-w-40 and STP. Dip the pistons in it before putting them in the cylinders. Just assembled my 6.9 and installed it. What I did to ensure good oiling was to take out the oil pressure sender from the back of the block, put a 1/8 NPT nipple in it, a rubber hose to that, and a funnel hung from the hood attached to the rubber hose. I dumped a mix of 10-w-40 and STP down the funnel while I worked on other things. That ensured all the oil passages, oil cooler, etc. were full. It took a long time, like several hours, because it was gravity flow and thick because of the cold and STP. But, on first crank, it came right up to 30 psi immediately.

 

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