Good Morning. Last time since full oil and filter change was probably 7-8 years ago. Haven't been overly concerned about it since it gets ran so infrequently for # of hours the last few years. Dad was always a believer of straight 30wt oil in these older engines, he wasn't big on multigrade so that's what I've kept in it and what I've always topped it up with.

I did notice the fuel pressure gauge is reading off, should have a new one here in a few days to see if its the gauge itself or its leading towards other fuel system issues.

I'll give the Stanadyne a try - I've periodically put that in my truck and always seemed like it was good stuff.

The operators manual for the 51B series says the cooling system should be a minimum of 160 and the max is dependent on load and outside temperature but never to exceed boiling. Only time I ever saw anything over 200 on it was when the radiator was slam full of trash. Ever since we cleaned that out, it's been running where it has.

What would you guys consider a high # of run hours on the hour meter that would be an indicator it's just time for rings and rebuild? 6-7-8k hrs? Somewhere in there? Not sure why I never thought to just look and check on that. It did ran a lot back in the day.

CHANGE THE OIL.
Bob

when you do injector capsules you usually re-kit the the pump itself as well. any good injection service should be able to do this for you. and its a good idea as you know its right then.
just mark everything when you take it apart. and spill time it to check the timing.
the valve guides are easy enough to check remove the valve covers and have a look.

try a oil and filter change also try using 40 or even 50 weight diesel oil. multi-grade oil is superior in most applications. delo gold 15w40 works well in many of these older cats. oil technology has moved on since the 1940s

check the thermostat works properly. a infrared thermometer is a handy tool to get actual rad and block temp.

as neil suggests it could be stuck rings.

and yes you need to load it up properly to get it properly hot and make it work. ask your electrician he may know where you could hire a load cell the other way is pull the alternator off and hook it up to a engine dyno.

you genset may be a bit over sized for the task the average house would flat being 15 to 20 kw. cuase 220v at 80amps is only 17.6kw yes a genset needs to be larger then the load to be able to start the loads as you dont have grid inertia behind you. and yes there is a difference between kva and killowatts one is apparent power the other is actual power.

sadly the only way to check the wear in the bores is to remove the heads. as it has sat for long periods and run lightly loaded it probably has stuck rings.

An update to this machine;

Got new fuel pressure gauge - put on, ran briefly, still showing bottom of red on fuel pressure at idle. Ran up to operating speed, barely registered in red, estimating 3-4psi of fuel pressure. Original cat gauge was 0-15 from what I've read so something was obviously wrong. I only suspected the original gauge was stuck before, not that it was registering correctly.

I had just had new hoses made from the fuel tank and they were clear and had fuel the same time I put the gauge on (as a preventative measure since they were old and didn't want any leaks starting).

So I got to reading my service manuals and parts books and discovered the fuel bypass valve may have been stuck, or had trash under it, not allowing it to seat properly, which would have let it build pressure. I took the cover off where the spring, cup, and plunger are supposed to be at, to only find the cup! No spring, no plunger, at all. How this could have happened, my only assumption is that sometime in the past when Dad had this machine in the shop or apart, it got lost/fell out, whatever, and just didn't get put back in. That would have been easily 25+ years ago, so it's been this way a very very long time unless they somehow just dissolved in there. Dad was an expert at equipment and Cat stuff in particular for his entire life, but unfortunately in his later years he became more forgetful as the dementia and old age set in.

My parts book for the 51B series called for the following part #s in the fuel bypass valve parts;

7H9922 - Spring
8B8917 - Plunger. Regal Corp gave me a superceded part # of 2S4015 for this one. They had a new aftermarket one that they sold with the spring to me.

The plunger is not pictured very well/detailed in the parts book or the service manual. I was expecting a rod that the spring and cap went behind, and its more like a button with a point on it that the spring fits into the back of. But this is what I got.

In other unfortunate news, while I was waiting on these parts to arrive, the generator quit putting out power after hurricane Helene, and I had to go get a small portable generator to replace it. Engine was running, just no electric.

So in the next few weeks I'll put these parts in the bypass valve, see if that fixes my fuel pressure issue, and probably go ahead and pull the whole thing out from where it is into the shop and start working on diagnosing the power generation issue and dive deeper into the engine to solve the slobbering issue I guess.