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Thread: Checking Engine Gauges On An Unfamiliar Boat

  1. #1
    Contributing Member I Ensenada Crab's Avatar
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    Checking Engine Gauges On An Unfamiliar Boat

    so having recently purchased an E32-2 with a 5416, i noticed upon arriving at the boat, the water temperature gauge shows 150 (F) and the tach 400 rpm. both gauges move appropriately once the engine is up and running--but i am left wondering if the rpm and water temp are accurate. i suppose i can measure the voltage coming to the gauges but all that tells me is (maybe) if the sending units are working. not so concerned about the rpm as i am about the water temp. it seems to take a long time before the engine warms up which makes me wonder about the thermostat working properly.

    any ideas aside from replacing the gauges? i didn't think to tap on the gauge faces but i will next time down.

  2. #2
    1984 Ericson 30+, Nanaimo, BC
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    Our 5416 engine regularly runs at about 175 degrees on our temp gauge, just for info. We have a160 degree thermostat.
    Frank

  3. #3
    Principal Partner Tom Metzger's Avatar
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    Here is the info on your gauges, from Teleflex via Jamestown Distributors:

    Water Temperature System (Inboards & Stern Drives)
    1. To test gauge, voltage from "I" to "G" terminals must be 10-16 VDC. No wire on "S" terminal. Gauge pointer should rest below 120. Next, connect the "S" terminal to the "G" terminal (leave "I" and "G" terminals connected). The gauge pointer should rest above 240.
    2. The resistance of the sender can be measured to determine the sender's correct operation. Remove wire to gauge. Connect an ohmmeter to terminal of sender and to engine block. Approximate values are: 75 (room temperature) = 600 to 800 ohms; 212 degrees = 55 ohms. (These are single station values- twin station values would be 1/2 these numbers).
    3. If sender is shorted (0 ohms) gauge will read above 240F.
    4. If sender has infinite resistance (Open) gauge will read below 120F.
    5. If the gauge reads lower than expected, was sealer used on the sender threads? (See illustration.)
    6. The accuracy of the system (gauge, sender, voltage range) can vary as much as 16 degrees at 180F.
    7. Use of pipe extenders to plumb both a sender and temperature switch (for horn or warning light) from one port is not recommended. The amount of weight extended on the fitting of a vibrating engine could cause fatigue-related breakage. Also, the sender is removed from water flow inside the engine and will probably read cooler.
    8. Teleflex does not offer senders for metric threaded ports.


    Tach & Tach/Hourmeter (Diesel Alternator Type)

    (For Diesel or Low-RPM Inboard and Stern Drive Engines

    1. For this type of tachometer, the engine is usually a diesel, but can be a low-RPM gasoline stern drive or inboard.
    2. Check all wire connections to see that they're tight and not corroded. NOTE: Some older style tachometers operate with only Ground and Sender connections. Teleflex tachs must have 12 VDC (from the ignition switch, "ON" when engine is running) to the "IGN" stud.
    3. When tachometer is first turned on, pointer must go to zero 50 RPM. If not, check connections (if OK, tachometer is probably faulty).
    4. Voltages with engine running should be: IGN to GND terminal: 12 VDC minimum; SEND to GND terminal: 5 VAC minimum.
    5. Arrow on rotary selector switch must be pointed directly at setting or the tachometer will go to full scale.
    6. Some alternators do not have output terminal for tachometer signal. A local alternator repair shop can install a tap from the internal rectifier to facilitate a tachometer signal from the alternator.
    7. If the number of alternator poles is not known, measure actual RPM with a Master Tachometer. Rotate tach selector switch to the letter that puts the tach closest to actual RPM. Final calibration adjustment requires a Remote Master Tachometer. Connect the master tach and start the engine. At about 1,500-2,000 RPM, use a jeweller's screw driver to carefully adjust the potentiometer in the "CAL" hole (about 10 o'clock on the rear of the tach), bringing the tachometer into agreement with the Master Tach. Only a minimal amount of turning is required. Overtorquing of adjustment will damage gauge mechanism. Turning clockwise increases tach reading, counter clockwise reduces reading. If the tach cannot be brought into calibration, the black Range Selector Switch is probably on the wrong setting.
    8. Alternator belt slippage will cause some error on the tachometer.
    9. Dual stations: the send er will drive two tachometers. Simply connect "IGN" to "IGN", "GND"to "GND", etc. NOTE: mixing brands/ types (such as 2-wire/3-wire, see paragraph 2 above) may cause problems.
    Tom Metzger
    E-34 Xanthus

  4. #4
    Contributing Member I Ensenada Crab's Avatar
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    Not to Highlight my ignorance too much: but where would i find this thermostat?

    Quote Originally Posted by Frank Langer View Post
    Our 5416 engine regularly runs at about 175 degrees on our temp gauge, just for info. We have a160 degree thermostat.
    Frank
    It's obvious i need to spend some time just sitting with my 5416 following hoses and wires. but in the meantime, i am assuming the thermostat must be located above the fresh (not raw) water pump? is it a standard automotive part or a unique part made for marine diesels?

    i have found a couple of PDFs covering the parts of a 5416, but nothing like a chilton guide to a 225 slant six. is there a book that covers servicing these engines?

    i suppose there is no shortcut to learning about something over the years. . .no magical guide to being ready for any problem.

    thanks so much for everyone's helpful comments to date. i hope to make it up to nanaimo late next spring, after the life threatening weather system's have passed.

  5. #5
    1984 Ericson 30+, Nanaimo, BC
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    The thermostat is located directly above the fresh water pump, just a couple of bolts to undo the housing. There is a paper gasket.
    The thermostat looks exactly like an automotive one, and it would function the same if you can find one that opens at about 160 degrees. There has been previous discussion on this site about trying to run at about 180 degrees, which some say is better for the engine. I would think that if an automotive one fits in the space, it should be ok, but I'm not a mechanic.
    I tested mine a while ago using a meat thermometer in a pot of water on the stove and watched it open as the temp reached 160 degrees, so I could tell it was still good. Maybe you don't need a new one, though it's a good idea to carry a spare.
    I found a 5416 diesel service manual on line for free download some time ago, so an internet search might be worth a try. The service manual is helpful, but not as detailed in my opinion as a chiltons car manual.
    Frank
    Last edited by Frank Langer; 11-19-2018 at 03:45 PM.

  6. #6
    1984 Ericson 30+, Nanaimo, BC
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    You mentioned it taking a long time to warm up your engine. I find at this time of year my engine won't get to operating temp by idling at dock for 10 to 15 minutes. I have to leave the dock after a brief warmup and run at about 4 to 5 knots for another 10 minutes or so, then at normal speed of about 5.8 knots for a few minutes to reach full operating temp. I think the air and water are just too cold this time of year. Maybe it's the same for your engine, and it might be fine. ☺️
    Frank

  7. #7
    Principal Partner Tom Metzger's Avatar
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    Diesel engines don't warm up at idle like gas engines do. They have to be under load. That's why diesel stand by generators have a resistive load bank for periodic exercising.

    That was from my veritable gold mine of useless information.
    Tom Metzger
    E-34 Xanthus

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