Diesel slow to accelerate?

[Hankasail]

Originally Posted by sailorchic34

Check the discharge elbow for carbon buildup. That can cause a diesel not to rev.

I think sailorchic34 is right on target. I had the same symptoms you described with my Yanmar 3GM30 and 3 different Yanmar dealers told me to check the mixing elbow in the exhaust system. I checked it and found it was almost completely blocked. Apparently this is a common occurrence with Yanmar engines. If the engine can't get rid of the exhaust it can't breathe and loses power.

[Symphony]

I assuming "slow to accelerate" means the engine RPM is slow to increase.
OPs engine is a Yanmar turbo.
Exhaust elbow or more likely turbo
here's a DIY link to check the turbo
Marine turbo chargers, love them or hate them they are here to stay

[briblack]

thanks for all the good input. I meant that the engine was slow to increase RPM's, not that the boat itself was slow to increase speed through the water. We put a new mixing elbow on her two years ago, but I suppose it could be obstructed.

[SteveInMD]

Good luck with the repairs. Let us know what you find.

[Kenomac]

Originally Posted by briblack

thanks for all the good input. I meant that the engine was slow to increase RPM's, not that the boat itself was slow to increase speed through the water. We put a new mixing elbow on her two years ago, but I suppose it could be obstructed.

With or without a load? In gear or in neutral? When was the last time the bottom and prop were scaped and cleaned?

Without answers to these very basic questions, nobody can give you a good suggestion as to the source of your problem.

[SteveInMD]

I totally agree! Troubleshooting is a logical step by step investigation based on inspections and testing. Short of that it's just guessing. Guessing can be a very expensive way to fix an engine.