Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 10-09-2017, 09:38   #1
Registered User

Join Date: Nov 2012
Location: Boat is in Annapolis
Boat: 1991 Island Packet 29
Posts: 9
6000 RPM Tach On A Yanmar 2GM20F

New boat to me. Previous owner installed a new Yanmar Mack "C" panel with a tach that goes to 6000 RPM. Specs for the engine show max RPM rating is 3600 with a continuous rating of 3400. Had some other issues with the engine and asked a reputable Yanmar certified yard to take a look. One thing they want to correct is the tach. They say I should be using a 4000 RPM tach and should replace the one there now. Is that really necessary? Wouldn't the 6000 show the proper readout? What would be the issue keeping what is currently there?

The original tach that came with the engine when new was presumably a 4000 RPM.

Thanks,
Joe
Baysailor34 is offline   Reply With Quote
Old 10-09-2017, 09:50   #2
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,483
Re: 6000 RPM Tach On A Yanmar 2GM20F

Frankly I wouldnt worry about it. The "spread " on the 6k tach doesnt allow you as many increments in your engine range, but realistically, once your are properly propped you cant go over RPM and most people adjust the throttle to the "sweet spot", smooth spot, near the speed they want to go. I rarely even look at a tach.

What are your other issues?
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 10-09-2017, 12:55   #3
Registered User

Join Date: Jan 2008
Location: SF Bay Area (Boat Sold)
Boat: Former owner of a Valiant V40
Posts: 1,143
Re: 6000 RPM Tach On A Yanmar 2GM20F

Only issue I can think of ...,
Is the existing tach accurate?
Get an (inexpensive) laser tach and check the existing tach against reality. If it is close enough, no worries. If not ...
jamhass is offline   Reply With Quote
Old 10-09-2017, 12:55   #4
Registered User

Join Date: Jan 2008
Location: SF Bay Area (Boat Sold)
Boat: Former owner of a Valiant V40
Posts: 1,143
Re: 6000 RPM Tach On A Yanmar 2GM20F

Only issue I can think of ...,
Is the existing tach accurate?
Get an (inexpensive) laser tach and check the existing tach against reality. If it is close enough, no worries. If not ...
jamhass is offline   Reply With Quote
Old 11-09-2017, 15:19   #5
Registered User

Join Date: Mar 2015
Posts: 104
Re: 6000 RPM Tach On A Yanmar 2GM20F

I would forget about it, The yard must be short of business.
M
MartinF is offline   Reply With Quote
Old 11-09-2017, 16:42   #6
Registered User

Join Date: Jan 2015
Location: Oz, PNG, Western Pacific
Boat: Adams 42
Posts: 79
Re: 6000 RPM Tach On A Yanmar 2GM20F

I would keep it.
It may come in to its own if you have a runaway diesel from ingested fuel.
Excessive or misdirected crankcase blowby and spilt flammable liquids. Are two events that I have experienced.

Cheers
Frugal is offline   Reply With Quote
Old 12-09-2017, 17:06   #7
cruiser

Join Date: Jan 2012
Location: Lake Ontario
Boat: Ontario 38 / Douglas 32 Mk II
Posts: 3,250
Re: 6000 RPM Tach On A Yanmar 2GM20F

Quote:
Originally Posted by Baysailor34 View Post
New boat to me. Previous owner installed a new Yanmar Mack "C" panel with a tach that goes to 6000 RPM. Specs for the engine show max RPM rating is 3600 with a continuous rating of 3400. Had some other issues with the engine and asked a reputable Yanmar certified yard to take a look. One thing they want to correct is the tach. They say I should be using a 4000 RPM tach and should replace the one there now. Is that really necessary? Wouldn't the 6000 show the proper readout? What would be the issue keeping what is currently there?

The original tach that came with the engine when new was presumably a 4000 RPM.

Thanks,
Joe
If the tach is working accurately, reliably, and repeatably, tell them to stuff it!

Rod Brandon
Sheen Marine
ramblinrod is offline   Reply With Quote
Old 12-09-2017, 17:52   #8
Registered User

Join Date: Aug 2015
Location: Sozopol
Boat: Riva 48
Posts: 1,382
Re: 6000 RPM Tach On A Yanmar 2GM20F

I had a lot of issues with my original Yanmar tach on the same engine. Then I realized replacement tach gauges from Faria cost $40-50 on Amazon/eBay. Replaced it and never looked back. No point in over complicating. Get one in a style that you like and replace it.
Pizzazz is offline   Reply With Quote
Old 12-09-2017, 18:11   #9
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,155
Re: 6000 RPM Tach On A Yanmar 2GM20F

This admonition from a "certified" mechanic is kinda scary (if he really believes what he says) or a real warning that you should take your biz elsewhere since he is trying to sell you unneeded parts .

In other words, the advice is ridiculous... kinda like saying you should replace the speedo in your car 'cause it goes up to 160 mph but your car will only do 110 flat out.

Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
Jim Cate is offline   Reply With Quote
Old 13-09-2017, 00:49   #10
Registered User

Join Date: Oct 2009
Location: australia
Posts: 539
Re: 6000 RPM Tach On A Yanmar 2GM20F

The mechanic is not pulling your leg. Your 6,000 rpm tacho gauge works on a different pulse frequency to the one that your engine presently produces. Have a look on the back of gauge as some have pulse change switches.
shakey doug is offline   Reply With Quote
Old 13-09-2017, 03:17   #11
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,155
Re: 6000 RPM Tach On A Yanmar 2GM20F

Quote:
Originally Posted by shakey doug View Post
The mechanic is not pulling your leg. Your 6,000 rpm tacho gauge works on a different pulse frequency to the one that your engine presently produces. Have a look on the back of gauge as some have pulse change switches.
doug, are you sure about this? Seems like the tach must be matched to the alternator on the engine, and they do vary in the number of poles and hence the number of "pulses" per revolution. But the tach is simply a pulse counter, and what its max scale reading is kinda inconsequential.

Another poster has suggested using an external tach to check the accuracy of the 6000 unit, and that's a good idea (for everyone!). Such a check will reveal what the truth is! Why for everyone? Because lots of us have changed alternators and pulleys and have no idea if there have been changes in the number of pulses per revolution, and hence of our tach accuracy.

Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
Jim Cate is offline   Reply With Quote
Old 13-09-2017, 05:40   #12
Moderator and Certifiable Refitter
 
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 20,305
Re: 6000 RPM Tach On A Yanmar 2GM20F

Quote:
Originally Posted by Jim Cate View Post
doug, are you sure about this? Seems like the tach must be matched to the alternator on the engine, and they do vary in the number of poles and hence the number of "pulses" per revolution. But the tach is simply a pulse counter, and what its max scale reading is kinda inconsequential.

Another poster has suggested using an external tach to check the accuracy of the 6000 unit, and that's a good idea (for everyone!). Such a check will reveal what the truth is! Why for everyone? Because lots of us have changed alternators and pulleys and have no idea if there have been changes in the number of pulses per revolution, and hence of our tach accuracy.

Jim
Hmm... the stock Yanmar tach is driven by a flywheel sensor. Who knows how this aftermarket tach is excited; my guess is the alternator but maybe not...
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Reply

Tags
2gm, 2gm20, rpm, yanmar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar 2gm20f - Black Water at 2700+ RPM cfoxcvg Engines and Propulsion Systems 46 30-08-2021 17:01
Yanmar Starting Issues and Tach Not Working Buttercup Engines and Propulsion Systems 0 05-07-2012 19:07
Troubleshoot Yanmar 4JH2BE Tach sailguam Engines and Propulsion Systems 10 30-11-2009 05:37
Yanmar 2GM20F tach Glenn Whaley Engines and Propulsion Systems 4 12-07-2008 03:47
Yanmar intermitant tach and instruments Celestialsailor Engines and Propulsion Systems 6 24-07-2007 19:50

Advertise Here


All times are GMT -7. The time now is 00:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.