Helppppppppp!!!!!!!

[Terry]

Guys,

Our new 310 is equipped with 2x 260HP, 5.0 MPI Seacore engines with BIII's.

We have just hit 20hrs when last night whilst on plane running 25 knots, running and sounding sweet, the starboard engine revs shot up and started fluctuating and there was a general loss of power from both engines.

We set everything in Neutral. Tick over was fine.  We set off again with low power. Eventually we were able to increase the revs and get to 14 knots with steady, but high, revs.  Then all seemed to right itself for a short time (15 mins) then the power loss problem and fluctuating revs came back.  We got back to the Marina (it was night so couldn't get to check things out) and she performed as normal at low revs for berthing.

Obviously we have reported to the broker and we are under warranty but wondered if anyone out there has had a similar issue and can guide our thinking?

Cheers 

 

[jjlovett]

Sounds like an engine alarm/limiter but I'll let the gear heads weigh in here... 

[trich11]

I have experienced something similar but it turned out to be simple. I picked up a piece of driftwood in the starboard trim tab. Engine would rev way up without much power but handled fine at low RPM. Hope your problem is something that easy.

[jpn]

Maybe one of the props are slipping???? 

[frodo13056]

If weeds get wrapped around your prop (or props) that will cause the exact same problem you described.  It's easy to clear the weeds out by stopping the boat, putting the drives in reverse and quickly "punch" the throttle sharply to clear off the weeds. Is it possible you ran through a batch of weeds?
Or, maybe you got some fishing string or something like that wrapped around the props?
As trich11 already said, a peice of driftwood will cause the same thing - it happened to me many years ago - hit a soggy 2x4 about a foot long and it actually impaled itself onto the lower unit. The engine would rev out of control and the boat would not plane until I jumped into the water and checked the lower unit and found the 2X4 and removed it.
Also, if you happen to pick up a plastic bag on the out drive, that could create the same issue but you'd overheat your engines in short order if that were the case.

[jpn]

Terry,

     Any updates on what happened????

[Terry]

Hi.  The brokers team went to check this morning but no sign of anything fouling the props or the trim tabs the the props were not freewheeling.  Awaiting the Mercruiser engineer to check her out.  I'll let you know as soon as I find out anything.  I was hoping it was stuff wrapped around the prop, now I'm hoping, as someone mentioned, that it could be a limiter - but the rough running sounded more serious than a limiter, but I'm no engine expert. 

[Terry]

Well...

The Mercruiser guys turned up...plugged in the diagnostic tool (lap top) and found.....nothing wrong.  I guess I should be overjoyed 
We took her out and she performed flawlessly.   The only conclusion our collective genius came up with was either:
1. Bag or something around the prop that eventually released itself when I got to the Marina
2. Water caused by condensation in the fuel causing a momentary loss of performance.
  Anyway, the good thing is nothing wrong.

The other event of the day is Mercruiser trying to rip me off for a 20hr service with a 100hr service!!!!  Sorted them out however.
 

[Terry]

To conclude this chapter, on the way to the service yard today (our Marina doesn't allow service nor does have the facilities) the same issue happened.  As it was daylight we could see the issue ----- Coconuts!!! They are bobbing around all over the place but bloody hard to see at night.  NEar impossible to see during the day.

Anyway, at least I know if it happens again then it is nothing serious 

Was wondering, based on the size of a coconut, the size of the boat and the size of the waters around Singapore, the odds of hitting a coconut, let alone twice 

[Dream 'Inn]

Glad to hear that's all it was!   Would've been a tough one for us Northerners on the Atlantic.  If we hit coconuts here then something's not right.   Our coconuts are called crab pots.

[ParkRode360]

Boy, that's a new one for "local knowledge" of the waters!    Glad you got it sorted!

[Terry]

Not coconuts it seems! 

Today we moved the boat from the yard after her service and after 1hr running great the same issue of the starboard engine high revs, low power appeared again.  This time there was not a coconut in sight, or anything else other than very large tanker ships.

The problem just wouldn't go away and we limped back to our marina.  Talking to the Mercruiser guys on the phone they are suggesting one of three things:
1. Clutch has gone!  Back to yard and lift her and fix it
2. Some rubber bush he said but I thought Bravo III didn't have a rubber bush??
3. Worst case the drives are F%@$£d
The worst part is he wasn't sure if this stuff was under warranty!!!!!

Anyone out there had same issues and would also have an idea if such stuff is warranty covered?
 

[frodo13056]

Ok - since you've eliminated anything in the water or stuck on the lower unit / out drive - my next guess is that your engine coupler is shot - and that would be due to a severe mis-alignment between the out drive unit input shaft and the engine or a faulty coupler.
There is a coupler that bolts to the engine flywheel and the out drive input shaft then slides into the coupler. The couple is made from rubber and has a metal insert where the out drive input shaft spines engage with the metal insert on the coupler. The coupler is a mechanical coupler and is what transmits engine rotation to the out drive and makes it go roundy roundy.
Usually when a coupler starts to fail, it will not fail 100% to where the engine will spin and nothing is transmitted to the out drive.....but rather what you are seeing which is basically an intermittent failure where the engine revs up but no action from the drive. Usually, when a coupler goes, there is a very strong odor at the point where the coupler is bolted to the engine - kind of a cooked rubber / grease smell.
If it is the coupler, then it is MOST CERTAINLY under warranty assuming you did not hit anything. If you hit something very hard, it is possible for the coupling to fail but you'd practically have to destroy the lower unit as well and for sure the props would be trashed. Even if it isn't the coupler, you do not expect a brand new boat to exhibit this type of behavior and whatever the cause, it darn well better be under warranty unless they can show you hit something, etc.
Let us know what you find!

[alswagg]

I would not think the coupler would be bad since you mentioned it slipps sometimes and not other.  If the coupler spinns, the engine will spin excessivly to high rpm and provide some propulsion at low rpm.  It will not suddenly grab and provide propulsion for top end performance.  Although the clutch will do this in some instances.  Certanly should be under Mercruisers warranty.  If the clutch is diagnosed the problem make sure they replace the entire drive assy and not just the upper.   Al

[Terry]

Hi Frodo, Alswagg.

Thanks for taking the time to go through this.  I have read a few posts now about alignment leading to issues!! This is Mercruiser or Rinker that does the final alignment?

Seems it could be the coupler or the clutch.  We didn't detect a burning smell.  We do get grip to push the boat along at 12 to 18 knots but the starboard engine is 5k to 6k rpm whilst the port engine is 3.5k rpm.  May be it is the clutch then.

Taking her for a sea trial with the Mercruiser engineer tomorrow.  Somehow hoping the fault appears and we can start getting to the bottom of the issue.  Very very unhappy about this after such a short time
I am very confident we didn't hit anything more than a coconut.  The props look fine and Mercruiser who did the service on Wednesday didn't raise any concerns.

Will let you know how it works out.