Hi Meridian,
I too have the 1976n V555M, the N/A version and have had since '85. It has run well for ~5,700 hrs now,but there are some things to look out for.
Now the diatribe. I took the liberty of copying my last post on B.D. to save some time.
I have a V555M, the natural so some things may vary but basically this is it.
ZINCS: -- One big one L.H. lower corner of the heat exchanger when facing engine.
--Another on the gear cooler. BE CAREFULL HERE. Cut the pencil to NO MORE THAN 9/16" from the shoulder or you risk damaging one of the water tubes and breaking the solder joint. These coolers are no longer available from Cummins although maybe from Sendure for at least $500 + . I found out the hard way. Yours could be different but be carefull. They are a weel built cooler though.
The heat exchanger zinc will last 40hr or so. The gear cooler should be checked often 15-20 hrs/ Check them often enough to figure out your changeout cycle. I would say the little one at least 2X or 3 X the rate of the big one.
COOLANT: ~ 40 litre each engine of 50/50 mix. [~10.5 usg ea]
You MUST use DCA or it must be present in whichever coolant you purchase if you buy a ready mix or risk liner damage. There are test strips available to check the concentration. It´s not hard to do but must be done and maintained. Every 2 years.
I do mix my own with DISTILLED water and DIESEL low silicate antifreeze. One jug water and one jug A.F. plus 4/5 bottle of the DCA which is a pint bottle. Do not just pour the whole DCA bottle in or you will end up with a too high concentration requiring removal of a bunch and redoing it. I do the initial mixing in a 2 gal bucket. This mix should result in the DCA concentration at the low end of the OK range but in that OK range.
Install a new coolant filter if your engine uses one.
Then run the engine to heat it up, mix it up and when cool do the concentration test. Take it for a run under load for an hour or so. It is easy to add a bit more DCA to raise the concentration. It is a PIA and a waste to have to reduce the concentration.
Don't try running it in the slip as that will not heat this engine unless you run it for a LONG LONG time which is not good.
-- CUMMINS P/Ns
coolant fltr 4 unit DCA60 WF 2071
Additive - DCA60 DCA 006000LX
Coolant test strip 4 strip pack CC2602-A
The A.F. is your choice as long as it is rated DIESEL - LOW SILICATE
I do use whatever Cummins has on the floor which is Zerex Diesel low silicate.
RAW WATER PUMP:
SOme time after mine they changed to a cog belt drive. Mine has the twin V belts with a 3 plate design of sheave for tension adjustment. PIA. Be carefull as these plates are no longer available so if you break one or lose it you will have a big problem. Again, not hard to adjust but it is slow and a pain. The bolts do not need to be more than snugged up firmly to lock the plates. You will NOT get the belt tension exactly even.
I fully rebuild mine every 5 yrs with new impeller, new bearing, new seal, new cover gasket, new belts. The cam plate i replaced the last time although after comparing to the new one I didn´t need to change it. It´s now a spare.
I also replaced the back wear plate and the cover plate. It did need it.
VALVES AND INJECTORS: Need the book, really is a must have.
DO NOT UNDO THE VALVE CROSSHEADS untill you have checked them and found they do indeed need adjustment. Leave them alone unless they need adjustment Other wise it´s just a whole lot more work AND you introduce another chance of error. They usually are fine. The valves themselves may need adjustment, or not.
INJECTORS: Must have the book for the procedure. You can use a torque wrench. NOT THE CHEAPO CRAP or chance damaging an injector. You can also search e-bay for the Cummins imjector setup measuring tool. I picked one up a couple years ago. In the past I made some probes for a dial indicator and used a mag. stand. Twas a pain but worked. The tool I bought is faster and less prone to causing errors.
The timeing marks are on the flywheel. There is a hole on the R.H. side when facing the engine front, just to the side of the PT pump.. The barring shaft is on the side of the PT pump with a hairpin to keep it from sliding into engagement accidently. The shaft is spring loaded with the hairpin an extra safety. I believe the shaft requires a 5/8 socket, maybe 9/16 but easily checked.
There is an owners manual on the Boatdiesel site in 5 parts that outline the procedure. Also a parts book. Both for a ´76 but it should all be the same. The fuel feed differences are in the PT pump, not the injectors.
These engine do live by the valve and injector adjustment though. There is no inj. pump timeing per se like many engines. The PT pump supplies fuel under varying but relatively low pressure. The injector finishes the job of timing from the camshaft and raises the pressure MANY times, apparently as much as up to 20K psi.
So take your time here and do it right.
ENGINE OIL:
I simply use Cummins Premium Blue 15/40 but as long as the oil is a major diesel rated oil you have a wide choice. Mine requires at a minimum CC, not been available for many years, but the oils now are up to CJ-4 so much better. CC & CD were 20+ yrs ago. Yours may need a more updated oil, engine yr. of mfgr. and the turbo, so with current oils you are covered.
Depending upon your filters you may need between 20+ litres up to 30L. I simply upend a 5 gal pail into the sump. I do have the bypass filter which holds ~ 5-6 L so subtracting that leaves your needs without the bypass filter at ~ 25L. The FF filter needs about 2 L. I would not put all that in right away the first time but maybe 22L and then start and check after shutdown. These pans, at least mine, hold enough that a couple litres or so low at idle is not critical.
If you have the bypass filter, a large black canister, then add about 4-5 litres of oil to it after changing the element. If you don't then no big deal.
When I bought the boat years ago I was told 32L. After a while i realized it should be about 30 tops . The engine , at 32L , was constantly using oil. At a high of 30L it goes many, many hours before I need add more. If you do not have the bypass you will simply have less oil in the system but the pan level should be the same.
I did monkey up a pump to fill the filters and prime the engine but before that I would disconnect the power to the fuel control solenoid and then crank the engine for two or three 15 sec shots. Then reconnect and let it start AT IDLE untill oil pressure came up.
FUEL FILTERS:
Yours will likely be different from mine. However, these engine can purge small amounts of air so are not nearly as picky about priming as many diesels. Just get the fuel close and it may stumble as the air is run out but it should smooth out soon.
I do not recommend just cranking and cranking although that will do it most times. Hard on the starter and maybe the PT pump.
I don´t know how your fuel system is arranged so you will need to have a good look. Hopefully the previous owner or builder made some provision to refill and prime the filters.
I have the primaries, then a standpipe, then the last ditch spin on. I have a small electric pump, normally valve isolated from the filters, which sucks fuel to fill the primaries. I just have to be sure to close the valve that isolates the tiny pump from filters. Once that is done I remove the standpipe plug and open the valve at the bottom and pour CLEAN fuel in. Then close the valve. I replace the plug after the engine is primed and running. Almost always the engine starts quickly and with a minimum of bumbling.
If there is a poor setup for filter priming then look up Tony Athens´ squeeze bulb priming and set that up. Next year I will be changing my setup to spin ons and I think I will copy Tonys´ idea.
As mentioned I do not warm it in the slip other than the time it takes to slip the lines and get moving after starting. Keep the load light and but increasing as the engine warms and it should serve you well.
You should have the owners manual at a minimum and the parts book. If possible the shop manual. They should still be available from Cummins on order, you will have to wait.
I hope I covered most of your questions.
If not then you can e mail me through the forum.
Good luck