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  1. #1
    Join Date
    Nov 2007
    Location
    Netherlands, boats in Portsmouth & Fethiye
    Posts
    563

    Default How to check diesel RPM?

    My Perkins 4108 idles very lumpily at an indicated 900RPM, but in all other respects is fine - no smoke or oil or water consumption, and it revs well. Before I investigate further I would like to check the actual engine idle speed - it may just be that the engine is idling to slowly. So what is the best way to check the rpm, without using the permanent rev counter? I have a Gunson strobe for the car, but that only works on petrol engines, as it takes timing off the spare plug lead.

    Thanks

    Neil

  2. #2
    Join Date
    Jun 2001
    Location
    Scotland
    Posts
    6,035

    Default

    Quote Originally Posted by neil1967 View Post
    My Perkins 4108 idles very lumpily at an indicated 900RPM, but in all other respects is fine - no smoke or oil or water consumption, and it revs well. Before I investigate further I would like to check the actual engine idle speed - it may just be that the engine is idling to slowly. So what is the best way to check the rpm, without using the permanent rev counter? I have a Gunson strobe for the car, but that only works on petrol engines, as it takes timing off the spare plug lead.

    Thanks

    Neil
    Lumpy running can be caused by a poor injector and exacerbated by a sloppy governor. Maybe get the injectors serviced at a diesel shop and if the lumpy running is not not cured then get the fuel pump serviced as the governor is inside it.
    Eastern Scotland and beyond.

  3. #3
    Join Date
    Jun 2005
    Location
    Mid Devon
    Posts
    5,140

    Default

    You need to borrow a strobe tester.

  4. #4
    Join Date
    May 2007
    Location
    Hampshire, UK
    Posts
    324

    Default

    Search eBay for RPM meter, very inexpensive: I bought one to check my rev counter and works a treat.

  5. #5
    Join Date
    Jun 2007
    Location
    Live in Kent, boat in Canary Islands
    Posts
    14,243

    Default

    Quote Originally Posted by Puggy View Post
    Search eBay for RPM meter, very inexpensive: I bought one to check my rev counter and works a treat.
    Or on Amazon: http://www.amazon.co.uk/exec/obidos/...H0/dolcetto-21
    ⓒ Nigel Mercier 2014
    FREE Bavaria Yacht Forum: www.bavariayacht.info

  6. #6
    Join Date
    May 2013
    Location
    Kirkcaldy, Fife
    Posts
    2,153

    Default

    You need a hand held tachometer. They come as either a contactless type that uses lasers or contact type where they have a wheel that you press against the crank pulley. Go for the laser type as your far less likely to lose all you fingers in a drive belt. ( I know someone who this happened too).

  7. #7
    Join Date
    Nov 2007
    Location
    Netherlands, boats in Portsmouth & Fethiye
    Posts
    563

    Default

    Thanks all. I am going to get the injectors serviced this winter and will bear the governer in mind. I had no idea that laser/LED tachos were so cheap!

    Neil

  8. #8
    Join Date
    Jun 2001
    Location
    Guernsey, Channel Islands
    Posts
    2,616

    Default

    I bought one and calibrated the tachies on Play d'eau. Two people required. One to control the throttle, note down the tachy and strobe readings, whilst the other manages the strobe.

    Simples.
    These are the voyages of Play d'eau....www.playdeau.com

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