Hello all my dear friends. I have yanmar yse 8 engine on my Tasman 26. Lately I decarbonised the engine, cleaned the air intake, changed the propeller and antifuled the boat. The engine is running incredibly quiet and strong. I would say 50% improvement.
The only problem is that if I try to put the throttle handle to 100% open it automatically comes back to 80%. I just can not understand why is that. It feels that the engine has some kind of response to 100% throttle. The interesting thing here is that even if I open the throttle more than 80%, those extra 20 don't to much only extra smoke but revs are not interesting when on load. For me is actually OK, it reminds me what is the max throttle that makes the engine happy. There in no really any benefits of holding the throttle 100% it only smokes more and smoke is black.
I am wondering why the engine didn't do this before the carbonising and cleaning the air Intake.
Is this normal? Does anybody else experience the same? It feels that engine in not comfortable when throttle is 100% and kind of bounce back then it works happy.
Is this only my impression or something is seriously wrong with my engine. Again it runs beautifully, better then ever and with 80% of throttle reaches the full hull speed even with the strong wind against me
Any explanation will be appreciated. Thank you my dear friends.
Keep intouch
There should be a travel limiting screw to stop the lever on the engine going too far. Perhaps you are trying to push it past that point and bending something.
I wouldn't be using anywhere near 100% unless in an emergency.
Hi Serb;
It's most likely to be the engine control assembly and/or cables. It's quite common for the older Morse type (like mine) to lose their friction and hence the ability to maintain position against the engine spring force at maximum revs and creep back. There might be some other cause, but that's a good place to start looking. A simple fix is to add some adjustable friction via a small clamp on the engine speed cable (two plates pulled together by screws which you can adjust). It's not pretty and you do lose a bit of "feel", but it works. If it's an older lever, parts won't be available. Their alloy internals can corrode too, so open it up and clean & lube it. Otherwise stump up a few hundred for a new lever.
It's quite likely that with all the frustration and upset you experienced from vibrations, noise and disappointingly low speed, that you didn't notice the throttle creep. It's a almost certainly a function of the control assembly and/or the cables, not the engine.
Cheers, Graeme
Thanks guys. Tried again without the handle and actually realised that the engine is actually pushing the throttle back because it feels that engine is raving 20 000 revs per min. Since I cleaned air intake, decarbonise and made it very responsive that engine is working 5 times better. It really feels that engine is creating some kind of resistance on 100%.
Anyway I won't change anything it is working mad on 80% and the boat is flying.
Just for the record, that green stuff which is added to the fuel costs around 130 bucks a liter but it works very well. I strongly recommend to everyone who has diesel engine on their boats.
