umar49•1mo ago

I finally figured out how to seat stubborn O-rings on injectors

Been working on a 6.0 Powerstroke last week and kept having the high pressure oil rail o-rings pop out during install. Tried greasing them, tried freezing them, nothing worked for more than a few seconds. Then an old buddy from my shop days told me to try a little bit of silicone lubricant instead of assembly grease. It's a bit thicker and holds the ring in place way better. Got all four seated on the first try after that. Has anyone else found a better trick for keeping those little rings from rolling out on you?

4 comments

4 Comments

mark_ward1mo agoMost Upvoted

Those injectors use a 7.3 Powerstroke on the high pressure rails, not a 6.0. I'd know because I've had both apart and the seals are different sizes.

brianm661mo ago

Wait, are you sure about the seal sizes being the main difference? I've messed with both too and the real issue isn't just the injector body size but the high pressure oil rail fittings. The 7.3 uses different threads and O-ring grooves than the 6.0, so swapping them isn't a straight bolt-on deal. @mark_ward has a point about the seals, but the actual mounting points and oil rail port depths are what cause most guys trouble when they try to mix parts. The high pressure oil system on a 7.3 runs at way lower pressure than a 6.0, so the internals just aren't built the same. I've seen a guy ruin a set of heads trying to force 6.0 injectors into a 7.3 rail, it's a totally different animal. So while the seals being different is true, that's just the start of the headaches.

paulw531mo ago

Yeah I mean I get what you're saying about the rail pressures being different, but I think you're mixing up the 7.3 and 6.0 a little bit. The 7.3 actually runs a higher pressure oil system than the 6.0, not lower. The HEUI system on a 7.3 pushes around 3000 psi at the injectors, while the 6.0 is more like 2800-2900. And I've done a few of these swaps myself, the real headache is definitely the oil rail port depths like you said, but you can actually make it work if you machine the rails a bit. The O-ring groove sizes on the injector bodies themselves are the same between the two motors, it's the Teflon seals on the barrel that are different. So mark_ward is partly right, but the seal sizes aren't the whole story either.

the_tessa1mo ago

Tbh I remember reading on another forum that some guys were actually swapping the high pressure oil pumps between the 7.3 and 6.0, not just injectors. But brianm66 is right about the rail fittings being different. I saw a post where a guy tried using 6.0 oil rails on a 7.3 block and the threads stripped because the port depths were off by almost a quarter inch. That O-ring groove difference mark_ward mentioned is real too, I've heard of guys using Viton O-rings from McMaster to get around it, but it's a gamble.