Dozer hard to start

Firing right away seems like the glow plugs and injectors are working good, good compression etc. Could be leaking a little air in? The return test makes a lot of sense at this point. I don't know where to check for an air leak, you could try priming it with the hand pump before starting it, if that helps, then you know you're on the right track.

Wow, this sounds just like my D3C 6SL00662. I did change out the screen filter, check valves, springs and connection washers (5) at the transfer/priming pump and---I think that may have fixed my problem. I have only started once since doing that and it fired right up. Before I replaced the parts, it was acting just like Sethmill describes---plus there was a cloud of smoke when it finally did start. I will attach a photo of my transfer/priming pump BEFORE I did the changes and you can see it looks a little "moist".---and the photo was after I dried it off. I think the pressure was slowly bleeding off thru the seepage at the pump making it hard to start the next day. I'll know better if it really is fixed after a few more starts after setting for a few days.

Man, I CANT count the # of times a customer would throw a pump on my counter & be cussing & screaming about how it wont start..
I would go grab my 22mm wrench & while still at the counter, take that banjo bolt out, right in-front of him..
SOMETIMES it wouldnt hardly come out.. u had to push in & out on the bolt to break the sticks that were caught in the filter screen..
& when u show him, he usually says, I'm firing that f'n mechanic when i get back to the shop.. just go thru it & make sure its ok..
I offer to blow it out & he can take it back with him..?? lol.. THAT never happens.. as long as its off, go thru it..
Glad it worked out for u..& nobody got fired.. lol

I tried the return line test to see if i had air , looked good after a couple seconds, also tried pumping the primer pump before starting and that didnt help either... 60 degree here today and dozer started good, Thinking im low on compression...

I finally got the dozer on a job and worked it for a couple hrs. I have a tick when it gets warm, gauge shows good oil psi. Seems like I remember reading about trouble with valve guides moving on the 3046 ? Or maybe broken valve spring ? Any thoughts ? This may tie in to my poor starting.

Has anyone checked the valve clearances recently..?