Of course... I just bought another tool on eBay about 10 minutes earlier

Did a bit more work on this truck today... I tried cleaning up the nipple cup itself on the cylinder where the problem initially occurs, I used 280 grit sandpaper which isn't exactly "polishing", but I did remove some of the marks from the O-rings... these marks were not deep enough to catch a fingernail or even feel with a fingertip... but on reassembly it did seem to seal up with the shop air test. I had just put a new top injector o-ring in that same injector last night.

I will add however, that on my first test I didn't put all the bolts back in the oil rail... just a couple in the middle... I thought for a shop air test that would be sufficient, but maybe these things are very fussy with being completely bolted down and torqued, even for a quick shop air test.

Just passing on some results for everybody else to consider when troubleshooting... this is a particularly frustrating one to troubleshoot... hope this helps someone.

I should have my tool and O-rings next weekend... I will try cleaning up all the nipple cups when I install the new O-rings.. along with new top seals in the injectors, hopefully this thing will seal up completely.

I think someone mentioned earlier in this thread that everybody probably has some HP oil leaks, but they aren't even noticeable until they get bad enough to cause a no hot start condition. I work on a lot of 6.0's every week, and I have noticed some big differences in how quickly they all start, both hot and cold... probably due to these "un-noticed" HP oil leaks. I had a 6.0 excursion here last week that started instantly as soon as you touched the key... it was very noticeable how fast it started on a hot start... maybe perfecting the nipple cup seals is the way to make them all start this way!? I will provide my feedback here as it comes in.

Duane