Good points Francois, I have meant to take a good look at the prop and probably do need to send it off for reconditioning.
I know the bottom is a little dirty and so is the prop. But even when everything was freshly painted I still had this issue. It starts up very easily which makes me think that I'm running it at a decent load. Is there a way to determine the reliability and accuracy of the Tach? On Fri, Jun 1, 2018 at 9:30 AM Francois Rivard <jeanfrancoisriv...@gmail.com> wrote: > Hi Kevin, > > In addition to making sure the transmission is fully engaged (We had that > issue too, for me, it was solved with a simple cable adjustment), it sounds > like you should jump in the water and take a good look at your prop. What > you need to do is grab the blades and wiggle them against the folding axis. > So, not following the folding movement, the other axis -> back and forth. > If the tip moves more than 1/8 - 1/4 inch the hub and blades need a > rebuild. > > The Martecs only go so long before needing a rebuild which consists of > reaming the pivot axis hole and installing a larger diameter pivot shaft. > It sounds like a big deal but it's not: Last time I had it done Martec did > it for $80.00 plus shipping. > > The 3GM30F (I have one on my boat) is a small displacement engine (950 CC) > and by diesel standards: A High revver. It needs to cruise between 2800 and > 3000 rpm and should run about 3400 rpm flat out. If it's in good shape and > it can't achieve that something is amiss: Too much pitch on the prop / > dirty and draggy bottom / combination of both. > > When I had my prop redone Martec sold me higher pitch blades saying it > would "Run better" It didn't. All I got was cavitation and vibrations. > Going back to the original blades solved the issue. Yes, the blades with > more pitch were pitted (Obvious sign of cavitation), they looked like they > were infested with little crustaceans that don't exist in a lake. > > When Yanmar says you should run the engine at those RPM they are not > kidding. Prior owners of my boat ran it at low rpm too often and turned > the engine into a "Hard Starter" (What the local mechanics called it) as > not enough load and RPM caused excessive carbon deposits / fouled the > injectors / messed-up the whole thing. it was literally a 5-10 minutes > battle to get the engine running on the first start of the weekend every > time we used the boat when we first got it. > > I "fixed" the issue by running it at prescribed RPM / running it wide open > for at least 10-15 mins every weekend / using Diesel Kleen Power service > injector cleaner. It took over 20 gallons to really make a difference but > now the engine starts within a few seconds every time when cold and > immediately fires-up for the rest of the weekend. > > Good Luck, > > -Francois Rivard > 1990 34+ "Take Five" > Lake Lanier, GA > > >
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