Penta D1-30 with 130S saildrive low RPM

[Rufduck]

Help please.
D1-30 130S in Mahe. About 2400 hrs for both engines. Everything fine six weeks ago (noticed that WOT was perhaps 2900 on port engine but it was only a casual observation when I applied a periodic burst of full power) WOT gave 3000+ in neutral and about the same when stationary in gear for stbd and perhaps 2900/3000 port.
Now sitting in Nanaimo, BC with the port engine turning 3000+ in neutral but only 21-2200 in gear.
Changed fuel filter, no change. Dove and Cleaned prop (small amount of green hair) and no trash in prop, no change. Engine/drive fluids are Okay and drive oil doesn’t smell burned. If it was air filter, presume it wouldn’t turn 3000+. Noticed that off and in gear, that the prop will turn with some resistance but not like it is turning the engine but I don’t know the inner workings of the drive to know if it’s normal. Wish I had thought to compare to good side but was cold. Finally, when wife was doing the run up and retarded throttle to dead slow and in gear the drive made a lot clattering and shaking. Almost like too much gear lash or a bad u-joint in std auto transmission (I may be doing a bit of imagining at this point).
Apparently Nanaimo doesn’t have a wide enough travel lift nor a VP service center. Been working toward this trip since March but I’m not happy pushing into tidal rapids in narrow passages with only one engine.
What am I missing? Suggestions? Anyone? (Indistinct muttering not appropriate to print)...
Martyn Adams

[Thumbs Up]

Did you say that you performed this test while stationary? Clattering and shaking could be motor mounts. Could be overpropped. Could be miscalibrated tachs. Could be blocked exhaust mixer elbow. What has been changed or repaired recently? Start there.

[Xenofonte]

Hello, Mister Adams.
Sorry for my poor English.

The most problems fail in your engines is the near obstruction of the exhaust mixer elbow (REF 861906).

I recommend you unmount already your elbow of the port engine (It will have a about 98% stenosis caused by carbon deposits), and replace it by a elbow from key part.com , REF. 861906SS-R, made of 316 stainless steel. You must change too the Exhaust Elbow Gasket (ref 861907-R) , same proveyor.

You'll fix the problem.

The D1-30 w. 130s has to reach 3500 in stationary, and a max of 3200 in navigation. (Max revs recommended: 2800)

Good luck. Greetings from Malaga, SPAIN (EC)

pepeprego@hotmail.com

https://www.youtube.com/watch?v=rQs1GT0bOtk

[Xenofonte]

Thumbs up is Right.

Exhaust mixer elbow cleaning must be a essential part of the annual workup of this engine.

Saludos !