I fought by suburban starter for a year hard slow start, finally got a good one and bam start fast, but two good battery's is key, test both indivually, good glow plug system, and I usally up size all my battery cables, and lift pump, just cause it's purring doesn't mean it's pumping enough
I know I am changing glow plugs. What size is the socket for them. The lift pump I'm not to for sure how to check. I changed fuel filter could I have not gotten all the air out of the system when I did it?
Yes, air in system could cause a no start, or hard start. Fire it up and crack the injector line nuts loose one at a time. It will squirt out a little fuel, when you tighten it back up you hope is a small change in the sound.
3/8 or deep socket for the glow plugs. Soak them with your favorite penetrating oil first- I like pb blaster.
O'Riley starters I have had luck with 1 but I wouldn't bet the house on them. Otherwise I again recommend a NEW Powermaster. Glow plugs are not going to change cranking speed.
For grins you need 9v at the pull in wire at the starter and 11v at the battery cable on the starter minimum per the electrical shop I returned bad starters too.
New parts do not mean good parts. Reman parts even less so.