Ducatii 996 Possible Major Engine Failure.. Any Advise Please.

Is there oil and water still in it
would be my first question. If so then pull the alternator cover off and I'm sure your first guess would be correct.
Never had the alternator nut come loose but I'd guess the major parts, crank, rods, pistons, valves etc should all be ok. It'd just stall when it loses the spark.
Also, pull the plugs out, stick it in gear and try spinning the rear wheel. That'll tell if it's proper bolloxed or just alternator.

 

Well keep us informed on what you find. Sure more help will be along soon.
I'm probably gonna make matters worse by asking if you know a worn sprag can be fixed for about £5 too.

 

Ah. I've had sprag trouble too. So long as it's not battered the flywheel etc by keep trying to start it you only need the spring replacing. And a 50mm fork seal spring is perfect for the job. Never had to buy a new sprag in 20 years of owning Ducatis.

 

Did you rebuild the whole engine or just change the sprag clutch. It sounds like you could have big end failure or there is a plug in the crank web that if it comes loose can cause a lack of oil pressure, that's assuming you have no major oil leaks and all was rebuilt as it should be.

The sprag clutch may or may not be related to you present problem hence my comment above, you may need to look more widely. It may even be something as simple as a failing oil pressure sensor and or the flywheel nut coming loose or some other coincidental problem, did you loctite the flywheel nut and torque it correctly? I have had a flywheel nut come loose although it did not come undone completely and that just made a clunking sound when the engine was turned over by hand. Some of the 748-9** engines suffer from main bearing, and less so, big end failure and I have had a main bearing go on a 748R engine with just 4,000 miles on the clock. On stripping it was also found that the big ends were almost gone as well.

No doubt others could give you some more suggestions but these are just a few things that spring to mind that you might want to check out.

If it's a main bearing failure usually the alternator side casing will crack and this of course, if you lost enough oil, would cause the oil light to come on.

 

Are the cam belts intact?

 

Could be so many things as suggested, but going by symptoms it could be that one or both big ends have failed suddenly as if they have been wearing out gradually they don't usually seize a crank solid unless engine pushed really hard plus main bearings usually rumble/develop play rather than seize as they are conventional bearings not shells. Causes for a sudden oil pressure loss again could be due to several reasons but crank oil gallery plug unwinding (as said) is quite common and probably the most likely. Although often criticised for having greater than ideal clearance, oil pump failures are virtually unheard of and almost the same for pressure relief valve.

 

I'm presuming you pushed it home in neutral ruling most the clutch and gearbox out as potential problems.
As said check the belts. Mine still ran when a belt snapped though just had no power.
Might be time to become a real Ducati owner and split the engine for a good look inside.
Be an interesting one this.

 

If you can move the flywheel up and down then you may well have broken a main bearing. The bearings are in a plastic cage and if they break up and roll out I guess you could have one jam the crankshaft or get between the crank and the crankcase and jam it. They can make a bit of a mess when the balls are free to fall into the crank and crankcase area.

Judging by the metal floating about in the oil it looks like something has broken (up). Certainly further investigation is needed and possibly it is time to remove the heads and barrels and look into the crankcase to see if you can see anything amiss or seized. Many possibilities have been covered but to add one more item a ring could have gone and done some damage, although unlikely.

 

^ op said no movement on flywheel

 

I mentioned this to indicate what main bearing failure might feel like, if you have not experienced it before, and it's always worth a check. If the jamming is caused by something jamming the crank that is in between the crank and the crankcase there still is\may be the possibility of main bearing failure, which possibly could just be starting, or certainly worth a check. No doubt deeper inspection might prove what the problem is\might be.

 

I have a 916sp and it dropped a valve. The engine locked up on that big holes in the piston. That metal could be bits of piston and valve.
Whatever it is you are going to have to strip it down to find out