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Old 31 August 2010, 03:19   #1
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Mercury 2005 60 HP EFI/prop? warning bleep/over-revving?

Had the first trip out yesterday in the 4.7 SR with the above engine. Sea was slight. All well but a few times at the end (only out an hour or so) when I was pushing it a bit more the alarm went off; continous bleep - which according to manual points to over rev, cooling or oil prob. Oil level was fine, tell tale was flowing so pretty sure it was the revs.

Also when turning with power on it seemed to rev-up erratically a bit sometimes.

In the excitement of first trip, nervous family (incl 1 x queasy kid/pushed for time etc) I was not really able to try different secnarios to see exactly when it happened or check revs etc.

I'm not sure I had the trim set correctly if this has a factor but the engine was not excessively up.

Prop on there is a 10.5 x 11 which previous owner had on for watersports. The other prop I have is a 10.5 x 14.

Would welcome any advice on this from those who know these engines or can advise on prop etc.
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Old 31 August 2010, 04:20   #2
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Max, if it was me (bearing in mind that I know next to nothing about how engines work - someone more knowledgeable will add their comments, I just like to keep engines going!), I'd get it checked out.

The presence of the tell-tale only tells you that the impellor is working and lifting cooling water from the sea. If the thermostat isn't opening, that water won't be making it around the engine and you could still have a problem.

You could still have an oil pressure or valve problem even though the oil level looks right. If your engine was losing power when the alarm sounded, that's another indication of a problem.

Hope ita ll turns out OK
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Old 31 August 2010, 04:42   #3
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Originally Posted by Max... View Post
Had the first trip out yesterday in the 4.7 SR with the above engine. Sea was slight. All well but a few times at the end (only out an hour or so) when I was pushing it a bit more the alarm went off; continous bleep - which according to manual points to over rev, cooling or oil prob. Oil level was fine, tell tale was flowing so pretty sure it was the revs.
I'd agree with SeaSkills - don't assume that because the oil level is OK and the tell tale is working that there are no other oil/cooling issues it is alerting you to.
Quote:
Also when turning with power on it seemed to rev-up erratically a bit sometimes.

I'm not sure I had the trim set correctly if this has a factor but the engine was not excessively up.
It sounds like the prop is ventilating (getting too close the surface sucking in air, which is much easier to "chew" so it spins faster). Its maybe a shame that a RIB wasn't available during your PB2 - the instructor would have covered trimming in for high speed turns. Not sure if that would have been covered on the "big boat" or certainly been as obvious, as you are not usually trying to turn through 180 degrees at high speed on a cruiser. Would still have expected them to cover trim settings though?
Quote:
Prop on there is a 10.5 x 11 which previous owner had on for watersports. The other prop I have is a 10.5 x 14.
The 11" pitch does sound a bit small? Someone who's had a similar combo will be able to comment better - do you have a tacho (rev counter)? do you know what speed you were doing?
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Old 31 August 2010, 04:45   #4
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I reckon you need a 13" pitch prop on that boat/motor combo.

It will, in all likelihood, over-rev with a 11" pitch. what rpm were you running at when the alarm bell started ringing?
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Old 31 August 2010, 06:19   #5
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Thanks guys - really annoyed I could not have more time to try and pinpoint the conditions under which it happened but I could not stay out any longer with a sick feeling 7 yr old for fear of putting him off. When we returned up the channel everything was fine, no other factors to point to engine/cooling problem and when flushing with fresh water I ran it for 10 mins. Oil is nice colour and smell and level is perfect.

We covered trim in PB2 but again not enough time for me to experiment yesterday to get it right.

I'm 99% sure the alarm coincided with high revs - glancing at one point I am sure it nudged over 6000...

Brad - I have a feeling Matt said the same and that an 11 was too low and 14 too high.

Maybe best if I try and get out again with the 14 on and see if it behaves itself.

I have always serviced my own engines (Land Rover enthusiast) but I have no experience of outboards or electronically controlled engines. I really know I should get it maybe up on a dealer's diagnostics but this is a major faff/expense/huge round trip - of course safety comes first so I will take advice on this. I also need to find a marine dealer to trust - years of dealing with un-trustworthy car garages makes me wary!
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Old 31 August 2010, 09:20   #6
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will post it anyway as might be usefull for someone else!!

its the over rev alarm, as your running the fine pitch prop, IT MUST NOT GO OVER 6000 rpm,!! i have set the throttle so its just on 5950, if sea conditions are perfect or running with the tide, it could go over and the rev limiter will cut in giving a beeping sound, if you swapped the prop the prop to a 12 or 13 pitch it would disappear, in this case (you would have to unscrew the throttle stop as you would need more revs) to run a courser prop,as i have limited the amount of throttle you get as your running a fine pitch prop,
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Old 31 August 2010, 09:33   #7
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Thanks Matt - and for the PM. Are you sure that's the case, did it happen when you had it? - don't want to get stuck out there!

I'll swap to the 14 and see how it runs. How did you set up the throttle screw though? Is it a case of on a calm sea go to WOT and if it makes, say 5250 RPM, stop engine, cover off, wind out 1/2 turn, try again, repeat if necessary??!!
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Old 31 August 2010, 09:37   #8
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..running with the tide, it could go over
Could it?
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Old 31 August 2010, 09:56   #9
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its basically the same as running a car in first gear flat out, your gonna over rev it.
as the pitch is so fine, it will over rev, so you increase the length of the throttle stop screw to limit the throttle movement which is easy to find on the o/s rear quarter of the engine.
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Old 31 August 2010, 10:01   #10
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Or, keep an eye on the tacho and throttle back when it approaches 6k
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