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Johnson/evinrude adding a tell tale

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  • Johnson/evinrude adding a tell tale

    Adding a water pressure indicator to an OMC outboard.

    Tell-tale, tale-tell, that little squirty thing -- later model OMCs have 'em and you want one on yours.

    The water pump is a crucial element in preserving the health of your outboard. It's vitally important to know that it's functioning properly. That's where the water pressure indicator comes in. It functions by tapping into the water-jacket in your powerhead and providing a visible relief outlet, or "pee stream". The outlet is small, and has limited flow so water pressure is still maintained in the powerhead and doesn't all escape via the indicator.

    To retrofit the indicator, you'll need to tap a hole for a fitting in your powerhead's water jacket, put a hole in your lower cowling for a bulkhead indicator fitting and run a hose between the two.

    If you have an early 80s or late 70s motor, it may be adviseable to relocate, or modify the routing of the indicator's plumbing. Service bulletins have been included in the appropriate engine section where available. Included is a section on modifications at the end of the FAQ to cover some of these procedures.

    Adding the indicator outlet to the block

    OMC's early tell-tale equiped motors tapped into the bottom of the water jacket through the exhaust cover for the indicator's source. It was later realized that tapping in high up on the powerhead had the added benefit of removing any air-pockets in the cooling system, as well as draining the entire system after use. The latter has substantial benefit for winter storage in cold climes. Most later model OMCs had their tell-tale outlets located high up on the exhaust cover for these reasons.

    In retro-fitting a tell-tale, you have many choices for locating the indicator outlet on the block. Certainly, the exhaust cover is one, but on some blocks there are better choices. Wherever you choose to locate it, higher is better.

    At the chosen location you'll need to drill an 11/32" hole and tap it with a 1/8" pipe tap. This will accept either the OEM outlet elbow (P#321886 0r Sierra # 18-3290). All of these accept a 3/16" to 5/16" ID hose (P# 321887, 913435, or 327721) that will run to a bulk-head fitting (P# 0321885) through the lower cowling. When drilling the hole, apply grease to the drill bit to capture any metal shavings, and be sure to use a light oil on the tap so the threads are cut properly.

    The tap goes through the outer wall and into the water jacket.

    V-4 blocks
    The V-4 configuration presents some interesting issues for locating the indicator outlet. Typically the V-4s run hot on the starboard side. That's because of a tendency to develop air pockets high up on cylinder #1. By adding the indicator outlet to the top of the water jacket above cylinder #1 you provide an opportunity to "burp" any air out of the system and fix this issue. On many of the '73-'77 V-4 blocks there's a cast-in round boss just perfect for locating the indicator outlet. If you don't happen to have that boss, you can go in through the top, just behind the coil brackets also.

    Location of the cast-in boss w/ hole tapped.

    This location puts the outlet at a high spot in the cooling jacket. Also, since it's to the side of the block, it's easier to route to the side of cowling for the bulkhead fitting than an outlet located on the exhaust cover.

    Using the boss provides access high up on cylinder #1's water jacket.
    Last edited by tashasdaddy; August 5th, 2009, 02:10 PM.

  • #2
    Johnson/Evinrude adding tell tale continued 2


    Inline 3-Cylinder Blocks

    The recommendation for the inline threes is to place the indicator at the top of the cylinder block as per the following service bulletin. Even inline threes with factory installed tell-tales are advised to relocate from the exhaust cover to the top of the cylinder.

    3-Cylinder service bulletin (click for larger image)

    There isn't much room on the top of the block to place the outlet in the suggested place, but it is possible. You may need to space or remove the lifting eye in order to get proper clearance.

    Suggested location of water outlet.

    Another possible location is in the head, as seen in the following photo.

    Placing the outlet in the head.

    Complete installation of the powerhead outlet.


    • #3
      Johnson/Evinrude Adding a tell tale continued 3


      Important Addendum On Powerhead Fittings

      It is highly recommended that you use the OEM specified fitting on the powerhead. Especially, for use in salt water. Use of bronze substitutes available at auto-parts and hardware stores may result in electrolysis and corrosion of the threads in the aluminum block. Use the OEM fitting to be safe.

      Mounting the lower cowling bulkhead fitting

      Now that you've got the outlet fitting in the powerhead, you need a way to make the output visible on the outside of the motor. This is done by drilling a hole in the lower cowling and attaching the OEM indicator cowling fitting (P #321885) in a place that will be easily visible. This is usually placed in the rear of the lower cowling on the starboard side.

      Lower cowling fitting

      This fitting clips into a 11/16" hole. Now, not all of us have drill bits that big. You can get by with drilling a smaller hole and making an oval for the two clips with a small round file.

      The fitting then simply clips into the hole from the outside of the lower cowling.

      Indicator outlet lower cowling bulkhead fitting from the outside

      Indicator outlet lower cowling bulkhead fitting from the inside

      Routing the hose
      Now that you've got both fittings in place, you just need to connect them up with a hose. If you have not tapped the powerhead outlet into the very top of the #1 cylinder, it is advisable to route the hose in such a way that some part of the hose raises above the powerhead. This will prevent air pockets from forming in the powerhead and creating hot spots. Use zip-ties to clamp the hose onto the fittings, or leave un-clamped. There is very little pressure on the hose and it won't leak if it's in good shape.

      Advisable Modifications to Early Systems

      Service Bulletins
      Service bulletins containing re-location or re-routing instructions specific to engine type are located above in the following sections:
      • Inline 3-Cylinder Blocks

      Other Modifications
      Many of the early systems tapped into the water jacket at low point, and ran the outlet hose straight down to the bulkhead fitting. This configuration can cause air bubbles to enter the water jacket and cause hot-spots.

      Early OMC low-placed outlet with direct drain

      If you don't want to relocate the outlet to a higher spot on the engine, it is advisable to re-route the hose over the engine block to prevent air from entering the system.

      Routing the outlet line over the block.

      The Short and Sweet
      1. Drill 11/32" hole in powerhead providing access to the water jacket, thread with 1/8" pipe tap.
      2. Fit 1/8" pipe fitting with 5/16" nipple into the hole using either:
        • Outlet elbow (P#321886 0r Sierra # 18-3290)
        • Similar bronze fitting
      3. Drill 11/16" hole in lower cowling.
      4. Fit bulkhead fitting (P# 0321885) in place from the outside.
      5. Run a 3/16" to 5/16" ID hose (P# 321887, 913435, or 327721) connecting the powerhead fitting to the bulkhead fitting.
      Last edited by tashasdaddy; August 5th, 2009, 01:58 PM.


      • #4
        Re: Adding a tell tale FAQ submission

        Okay, so there it is. Had to split it up due to the 6-image limitation. Read it over and let me know if any issues cropped up in the translation.

        Also, the images are hosted at photobucket. If there's a better place here on iboats that we can put them I can re-link.

        And a special thanks to all who contributed.


        • #5
          Sign up today
          Re: Adding a tell tale FAQ submission

          Finally Larky did a 1971 50hp 2 cylinder. here are his pics.

          TEBOW Country

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