Re: [Amel Yacht Owners] Re: Yanmar 75HP - Cannot go over 2300 RPM

Bill & Judy Rouse <yahoogroups@...>

I believe that a repitch is nearly impossible. the AutoProp automatically pitches based on the rpm and the hydronamics of the shape of the blade. So a repitch of the AutoProp I believe requires reshaping the blades.

Since there is no adjustment in an AutoProp as compared to other folding/feathering props, low rpm has to be caused by any one of the previous suggestions.

If you want to know how I would rank the causes:
1.) Dirty prop
2.) Restricted fuel flow anywhere between tank and injector nozzles...tank, filters, fuel pump, injector pump, injectors, nozzels.
3.) Restriced exhaust/Turbo...valve lash clearance, exhaust manifold, elbow, rest of the exhaust system, Turbo needs service
4.) Prop needs bearing service
5.) Engine timing problem
6.) Fuel quality issue
7.) A C Drive issue
8.) AutoProp blade bent (wrong pitch)

I would eliminate one at a time beginning with the most likely to the least likely.

Bill Rouse
BeBe Amel 53 #387
Virgin Islands
Sent from my tablet
+1832-380-4970 USA Voice Mail

On Jan 12, 2017 10:05 AM, "SV Island Pearl II colin.d.streeter@... [amelyachtowners]" <amelyachtowners@...> wrote:


Hi Vladimir
Since Island Pearl II is the same 75hp Yanmar engine, same gearbox, and the original Amel supplied autoprop, and it easily does 3300 - 3500 when clean, I think you will find it is the turbo, not a need to re-pitch the autoprop. Good luck with it though. Hope you don't need to re-pitch that really nice prop.
Colin Streeter, Island Pearl II, SM#332

On Thu, Jan 12, 2017 at 11:49 PM, Vladimir Sonsev sonsev52@... [amelyachtowners] <> wrote:

As I stated above in this thread, I also have low engine RPM. It was 2500 RPM maximum when I bought my boat. I have 75 HP YANMAR with transmission 2.8:1 ratio. I contacted US Autoprop representative. He forward my question to the factory. See below their reply.  I copied and pasted it below.

"As far as I am aware Amel have not advised us about using Yanmar engine so this prop was never set up for this engine. Our records show that they only used Perkins or Volvo so it is not surprising that the pitch is out. Probably never right from day one. Say that however, it should not be too far off the mark in terms of engine loading. My best guess is that if the turbo is not working this is the reason for the low maximum rpm and not because the prop is holding it down."

My boat is on the hard now. I plan to check torbo when boat is in the water. I will conduct some other tests. If I could not resolve the problem I will remove the prop and send it to US Autoprop representative for a pitch change.


On Jan 11, 2017 7:16 AM, "David Pawley pawleyd@... [amelyachtowners]" <> wrote:

Its possible there are 2 types of injectors for the same engine, one set for derated. The difference would be seen in the nozzle hole Dia. Have you still got the old injectors!. Visual examination should be adequate but better to use nozzle cleaners. I have no idea if Yanmar have derated injectors, but other large bore engine manufacturers certainly have.

On 11 January 2017 at 16:34, 'sailormon' kimberlite@... [amelyachtowners] <> wrote:


The autoprop rebuild is not difficult just tedious and takes the  good part of a day.

If you Contact AB the bruton distributor in the USA they will sell you the bearings needed and rent you the special tools needed for the rebuild at a nominal price.

Fair Winds


Kimberlite Amel Super Maramu #376


Colin Streeter
0411 016 445

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