My truck and it's shenanigans.

[Hammerhead]

(01-31-2018 )IrishKW Wrote:  Possibly could be. I looked it has the new style seals. I suppose they could have damaged on when Cummins remaned the head.

What would be the best way to tell if they are bad?

The best way is to look for the presence of oil in the exhaust port. This indicates v/g seal leakage, but doesn't tell you why the seals are leaking.

***CAVEAT***this IS NOT for the faint of heart and requires extreme care and a soft touch!
Be honest with yourself, if you do not have extreme care & patience, DO NOT attempt this!
This is inadvisable for most people, but you asked...and you have been warned!

Remove the front rocker shaft.
Remove the front 3 injectors.
Place #1 at TDC, use the tool and remove the valve springs.
Remove the v/g seals, (yes this means you'll need to buy a set of v/g seals. Compared to replacing a head for no reason, CHEAP!)
Nudge, and I do mean NUDGE!!!! not bar, the motor SLIGHTLY so there is some vertical movement of the valves from seat to piston. DO NOT roll the motor over far enough to get the top of the valve stem anywhere near the top of the valve guide! 1/4" of valve travel is MORE than enough to measure lateral play
Use a dial indicator to check for lateral movement of the valve's stem in the valve guides, there should be very little lateral movement.
Nudge the motor BACKWARDS (back to TDC) and replace the v/g seals and springs. Yes I know you're never supposed to bar the motor backwards, but you're not barring it, you're nudging it. A couple degrees of rotation is not going to hurt it.
Repeat for cyl's 2 & 3.
The valves should have very little lateral movement of the stems in the guides, if so your head is unlikely worn out, and you just need v/g seals.
If you have no, or very little lateral movement of the stems, checking the rear 3 cyl's would be the next step.
Using a calipers to measure & record the valve stem protrusion of each valve for consistency will give you a very comprehensive understanding of the condition of your head.
After this, you have replaced all of the v/g seals, and confirmed the condition of the valves & guides.

***Be Prepared!!! If you roll the crank too far and the valves come out of the guides, you WILL BE REMOVING THE HEAD TO REINSTALL THEM!!! Once again, you have been warned!