In my limited experience
of rebuilding pumps (and they've all been Berkeley pumps...never done a Dominator so I'm not sure if there are many differences, if any)...
If you're just wanting to rebuild the pump so that you have a fresh working pump and you are mechanically inclined, I say do it yourself. At minimum, I recommend getting the 1/2" drive spline socket that goes over the splined end of the pump shaft, the 1/2" drive impeller nut socket, and the impeller puller to do it.
For the bowl you'll need a 3/4" socket.
Packing gland nuts are either 1/2" or 9/16"
Allen bolts on the bearing cap are a 1/4" allen
Handhole cleanout cover bolts are 9/16"
You'll need a set of flat feeler gauges for checking clearance, and a dial caliper is recommended for measuring these as I've found some to be marked inaccurately.
The thrust bearing is a interference/press fit onto the shaft.
The new impeller should hand fit (not be tight) onto the shaft
If you're gonna run a shouldered wear ring, the impeller will more than likely have to be shimmed back to give adequate clearance between the front thrust edge of the wear ring skirt and the shoulder.
Bowl removal can be done by removing the bowl bolts, then loosely threading in two of the bolts a few turns (one on either side of the bowl), then tap on the bolts alternately with a hammer to walk the bowl off of its register (the bowl sits on a register and is an interference fit onto this register so it will not immediately come off once the bolts are removed).
Depending on the impeller nut that is currently installed you may or may not have to cut it off as some of them seem to adhere themselves to the shaft pretty good.
I prefer to install the rope packings BEFORE the shaft is installed (easier to get them all the way in without having to use the packing collar). Once the new bearing is installed on the shaft, I wrap electrical tape around the impeller register of the shaft to protect the rope packings from getting damaged by it. You may have to tap the shaft through the packings by placing a piece of wood (preferably a dense type of wood that won't splinter when struck...don't ask me how I learned that
) on the splined end of the shaft and tapping it through the housing. The bearing will be a slight interference fit into the housing so the shaft will have to be tapped in all the way.
Most rope kits come with 5 ropes, however I've never been able to get all 5 in upon initial assembly. I run 4 and keep readjusting the packing gland as need as the new ropes seat during normal operation. Then once the collar is bottomed out (should happen after the first few trips out) I remove it and am then able to install the 5th rope seal.
For intial adjustment of the packing collar, I spin the shaft by hand and keep tightening the two packing collar bolts evenly until I start to feel drag on the shaft. Final adjustment occurs once the pump is installed and the boat is in the water.
Once the shaft is in I mount the bearing cap WITHOUT a gasket until it's snug, then measure the clearance between the suction housing and bearing cap. The bearing is clamped, or "crushed", into place by a register on the backside of the bearing cap. From what Duane at Hi-Tech Performance told me,
the gasket will crush 0.005"-0.010" if it is of the proper thickness. To determine if the gasket is of the proper thickness, you measure the gap between the back of the bearing cap and the bearing cap mounting surface on the suction housing, and the gasket should be 0.005"-0.010" thicker than this measurement. If it's too thin, you can either stack gaskets until the stack of them is the proper thickness, or use gasket material that is 0.005"-0.010" thicker than the gap measurement.
For the wear ring (DO NOT DO THIS ON AN ULTIMATE WEAR RING!!!), I use a map gas torch to melt the plastic insulator that's sandwiched between the housing and the ring. Once this is meted down, you can easily pry it out with a screwdriver. To install the new one (assuming a metal wear ring), I freeze them overnight, then install the new insulator in the housing around the wear ring housing, then use the old impeller to tap it into the housing. Make sure the front edge of the wear ring fully seats against the lip on the insulator.
Without the shaft key on the shaft, install the impeller as far in as it will go, then install the impeller nut snug. Measure the clearance between the -
For standard non-shouldered wear rings...the thrust face on the suction housing and the front edge of the impeller wear ring skirt
For shouldered wear rings...the wear ring shoulder and the front edge of the impeller wear ring skirt
This clearance should be between 0.025" - 0.125" If running a stock non-shouldered wear ring, it's typical to see 0.125" as this is Berkeley's factory blueprinted spec. You CAN either have the nose cone of the impeller OR the shaft register machined to get it closer if you wish.
With a non-shouldered wear ring, you will have some of the insulator lip sticking up with the wear ring installed. I take a razor knife and go along the wear ring and trim this excess off (NOT doing this was what caused my first pump to fail).
With a shouldered wear ring the impeller WILL be too close and will have to be shimmed. With the impeller installed without the shaft key and the nut snugged up on it, the front edge of the impeller wear ring skirt should be up against the wear ring shoulder. Check to see if there is a gap between the shaft register and the nose cone of the impeller.
If there is no gap - I install a 0.035" shim and call it good. This will set my shoulder - impeller clearance at 0.035'
If there is a gap - I measure the gap, and add that much shim to the 0.035" shim (example: if you have a 0.010" gap between the impeller register on the shaft and the nose cone of the impeller, I add a 0.010" shim to the 0.035" shim for a total of 0.045" shim.). That will bring the impeller nose cone - shaft register gap to 0, plus will set it back 0.035" away from the wear ring shoulder.
In the rare event that there is a clearance between the wear ring shoulder and the impeller wear ring skirt with the nose cone up against the shaft register, measure this clearance and subtract it from 0.035". This will be how much of a shim you will need.
Once you've figured out how much shim you need, remove the impeller and install the shims. Then reinstall and snug up the impeller. Use feeler gauges to check the gap between the impeller and thrust surface of the housing (wear ring shoulder for shouldered wear rings). I use a flat feeler gauge and stick it between the two, then drag it all around to feel for tight spots.
*NOTE: When using flat feeler gauges, check their thickness with a dial caliper. Don't trust what they're marked to be to be correct. I've seen some that are off by as much as 0.005".
According to Berkeley's spec, impeller nut torque and bowl bolt torqu is 75 ft lbs.
Bowl bushings are an inteference fit into the bowl. You can remove the old ones and reinstall the new ones by tapping them out/in with a socket.
Once the pump is fully assembled, spin it with a breaker bar and the spline socket and make sure you don't hear any rubbing or scraping and that it turns smooth without binding.
Once the pump is installed in the boat, the packing collar may or may not need adjustment. With the boat sitting in the water and the engine off, sit on the dock and watch how much water leaks through it. It shouldn't leak anymore than 1-2 drops per minute. If it's leaking more than this, tighten the collar bolts evenly in 1/4 turn increments, then watch it again. Keep doing this until you only see 1-2 drops per minute.
Hope this helps.