Trojan Boat Forum

Any thoughts on what might be the issue with CATs that get to 1500 RPM just fine, but try any further and RPM doesn't increase but starts putting out black smoke? I need to confirm if this is happening with both engines or just one; that would help isolate if it's something common to both engines ie fuel. Also not sure of model but hope to follow up. Any initial thoughts?

Usually caused by a too-rich air to fuel ratio. Leaky or stuck injectors, clogged air filter.
A few things to look at

Thanks T. Will pass it on. I'm sure I'll end up at it eventually though.

Lack of air?

Most common cause is a dirty bottom . Some black smoke when getting on plan can be normal and even a lot of smoke if pushing the throttles hard to get over the "hump" .

Good info. If there's more, keep it coming.

failure to get rpms above 1500 is a concern. On the turbocharged mid-80s Mercedes diesels we've driven for years, it's sometimes necessary (OK, useful) to really wind them up and blow out the carbon and fuel that (as I understand it) can gum up the turbocharger for lack of use -- called an Italian tune-up. Thing is, the rpms are climbing as you do this, typically in a lower gear, up in the 4000 range.

Couple questions:

What color smoke and how do the engines sound (smooth or rough) do they vibrate under load? Do they start easy?

If these are turbo charged motors then I would suspect you have lost a turbo. If this is the case and you keep running it watch out once the oil seals go in the turbo you run the risk of the engine running away on its own engine oil (I have had this happen with a truck driver trying to limp a truck back to our yard a few miles to avoid a tow); the only way to stop them once this happens is starve the motor for air or load it by putting the truck in a high gear and dumping the clutch (in a boat that's aproblem).

Natrually asperated I'd say the engines are working too hard (dirty bottom and running gear). I assume the overhead is set to the correct specifications.

I would not think both turbos would be bad , could be stuck if sitting , easy to check by pulling if the air cleaner .

BTW a turbo diesel would be more sensitive to a dirty bottom then a natural .