List,
I have 2005 Mercury 60 Bigfoot on my M. Typically at WOT she'll turn 5400-5500 rpm, with seeing 5700-5800 at sealevel. Just the other day I took her out for the first time this season and she's spinning at 6100! Truthfully didn't sound higher. . . like the tach was off. Is there a simple test for this, or does it sound like the tach needs to be replaced?
Thoughts?
Thanks
Bad tach?
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wardski
- Just Enlisted
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- Joined: Thu Feb 01, 2007 8:21 pm
- Location: Hood Canal, WA 04 26M, Suzuki 70 MACM0377A404
Re: Bad tach?
A long time ago I borrowed an instrument from work that was called a vibrating reed tachometer. It required no power and you just set it on the deck next to the motor. It measures the frequency of the vibration and you just read the RPM's off of it. Don't know how much they cost or where to borrow one from now, but was a slick little instrument.
PS My tach only lasted 5 years before I has to replace it - but the needle was frozen at 0 RPM's (lack of use).
PS My tach only lasted 5 years before I has to replace it - but the needle was frozen at 0 RPM's (lack of use).
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RobertB
- Admiral
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- Sailboat: MacGregor 26M
- Location: Clarksville, MD
Re: Bad tach?
If your tach is reading, it is probably working. Did you lighten the boat or finally store the anchor out of the water?
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Tomfoolery
- Admiral
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- Sailboat: MacGregor 26X
- Location: Rochester, NY '99X BF50 'Tomfoolery'
Re: Bad tach?
I had a tach on a Yanmar 3-cylinder marine diesel that would read low once in a while. It turned out to be a known problem in the harness, but I don't remember the cure. I sold it before I fixed it.
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Harrison
- First Officer
- Posts: 307
- Joined: Tue Jan 04, 2005 12:57 pm
- Location: Frederick, CO. '05 M, Merc 60 Bigfoot
Re: Bad tach?
Gonna check it again over the weekend. (hopefully weather will cooperate)
The best I've ever seen was 20.2 mph (miles) at about 5800rpm. That's fully loaded, mast up, 2 people and towing a dinghy in the Pacific. Here at altitude (5000+) I see about 18mph max at around 5500. Just last weekend (at altitude) 3 people, no mast, 16.5 mph MAX, but 6100rpm! That's what got me curious about possibly having a bad tach.
The best I've ever seen was 20.2 mph (miles) at about 5800rpm. That's fully loaded, mast up, 2 people and towing a dinghy in the Pacific. Here at altitude (5000+) I see about 18mph max at around 5500. Just last weekend (at altitude) 3 people, no mast, 16.5 mph MAX, but 6100rpm! That's what got me curious about possibly having a bad tach.
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seahouse
- Admiral
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- Sailboat: MacGregor 26M
- Location: Niagara at Lake Erie, Ontario. 2011 MacM, 60 hp E-Tec
- Contact:
Re: Bad tach?
You might want to check that your prop is not spinning on the shock-absorbing rubber hub. Mark them with a grease pencil, and see if the marks still line up when you get back from an outing. Unless you have already done this.
- Brian.
- Brian.
Re: Bad tach?
If its literally doubling the RPM check to see if there is pole switch on the back, (looks like a little dial) it tells the tach how many cylinders your engine is.Same problem on 1996 Nissan BF-50 tach is doubling the count?
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Harrison
- First Officer
- Posts: 307
- Joined: Tue Jan 04, 2005 12:57 pm
- Location: Frederick, CO. '05 M, Merc 60 Bigfoot
Re: Bad tach?
Harrison wrote:Gonna check it again over the weekend. (hopefully weather will cooperate)
The best I've ever seen was 20.2 mph (miles) at about 5800rpm. That's fully loaded, mast up, 2 people and towing a dinghy in the Pacific. Here at altitude (5000+) I see about 18mph max at around 5500. Just last weekend (at altitude) 3 people, no mast, 16.5 mph MAX, but 6100rpm! That's what got me curious about possibly having a bad tach.
Well all is good! Ran it again this weekend and it displays what it should. No erroneous displays.
