Official Caterpillar3116/3126 Thread

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by carterchapman, Feb 12, 2021.

  1. Njlarry

    Njlarry Active Member

    472
    May 9, 2021
    Chesapeake bay
    2000 400 DB
    Cat 3126
    If the engine runs ok without the racor and runs ok on the other racor then it has to be the racor. I seem to remember that they have some internal parts like ball on a spring check valve.
     
    dtfeld likes this.
  2. Njlarry

    Njlarry Active Member

    472
    May 9, 2021
    Chesapeake bay
    2000 400 DB
    Cat 3126
    I would strongly consider replacing the tanks while everything is out. Likely would switch to poly and be rid of the corrosion issues.
     
  3. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    Have you checked the primer valve (not the pump)? If that is not in the correct position, you will have power loss issues. From memory I believe that the valve "knob" should be in the 90* from the pump to be in the "run" position. It can be a bitch to get to as its on the bottom side of the primer pump assembly.

    Additionally, make sure the drain plug is sealed in the bottom of the bowl on the Racor...if it leaks, you'll see the same results. You can see bubbles in the racor bowl if this is the issue.
     
  4. nattydread

    nattydread New Member

    9
    Jun 19, 2022
    Bermuda
    1997 Sea Ray 370 Express Cruiser
    Caterpiller 3116s
    Not quite, it won't run with any racor on it, but does run without the racor.

    Yes, I did have a previous battle with that valve knob, but I can confirm it is in the run position.
     
    dtfeld likes this.
  5. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
    just to be clear - do you mean it runs OK without the filter element in the racor but still pulling fuel through the racor body, or bypassing the racor completely?
     
  6. nattydread

    nattydread New Member

    9
    Jun 19, 2022
    Bermuda
    1997 Sea Ray 370 Express Cruiser
    Caterpiller 3116s
    Bypassing the racor completely
     
  7. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
    techmitch likes this.
  8. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    The check ball is only there to prevent siphoning back to the fuel tank. There are no "springs". The only air leak areas are the lid gasket and the Tee Handle O-ring. All of the other seals will leak fuel.
    @nattydread - If you are seeing the fuel level down in the Racor when the engine shuts down you can be assured air is getting into the system before the Racor. If the engine is shutting down and fuel level isn't dropping in the Racor then something is preventing or stopping the fuel flow. A couple of things to consider -
    • The fuel solenoid Relay.
    • The fuel solenoid electrical connections.
    • The fuel solenoid adjustment into the injector assembly.
    • The eight little plastic check valves silted up in the injection assembly.
    • The siphon tube in the fuel tank partially plugged
    • The fuel hose from the tank to the selector valve and/or racor inner liner collapsed.
     
    dtfeld and techmitch like this.
  9. nattydread

    nattydread New Member

    9
    Jun 19, 2022
    Bermuda
    1997 Sea Ray 370 Express Cruiser
    Caterpiller 3116s
    Even though the engine runs normally with the racor bypassed completely?

    I have noticed the vacuum gauge does register when I put a vacuum pump on the engine side to pull fuel into the racor. However, the indicator drops back to zero once the fuel fill the glass.
     
  10. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
    The racor talk hit me thinking I should rebuild mine this winter. I see a gasket kit: https://pro.westmarine.com/racor-seal-kit-for-500-series-turbine-fuel-filters-108524.html

    I’d also like to add some drain valves. Are these correct? Ridiculously expensive, as expected: Racor U.L. Listed Brass Shut-Off Ma Turbine Retrofit Drain Valve https://a.co/d/2DrYKMT

    anything else I should replace while I’m in there? How about the bowl?

    I should probably cap the fuel lines, I’d rather not drain $7 diesel into the bilge. I’ll also shut off the fuel valves
     
  11. fwebster

    fwebster Well-Known Member TECHNICAL Contributor PLATINUM Sponsor

    Oct 6, 2006
    Middle Tennessee ; Panama City Beach, FL
    1996 450DA
    3116 Caterpillars
    I have, use and maintain several agricultural and construction diesel powered machines on my place in Tennessee, so I know how to care for diesel fuel in machinery and storage tanks.

    I owned my 450DA with 3116's for 25 years. I chose to buy all my boat fuel from a Valvetech dealer who filtered all his fuel at the point of sale, and I always used the additives I recommended in the "Diesel Management Article" posted in the tutorial section. I changed the Racor elements and flushed the Racor bowls annually and never saw the need to tear the Racors apart and rebuild them.

    This isn't to say you shouldn't rebuild your Racors but I posted my experience with them to suggest that you examine yours carefully and be sure you really need a rebuild before you get diesel fuel all over your garage or basement.

    The. bowl drain valves are a worthwhile addition and you can find UL rated liquid valves from other vendors online for less that the "pot of gold" Racor asks for theirs.
     
    dtfeld likes this.
  12. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    https://www.mcmaster.com/fuel-valves/compact-threaded-on-off-valves-for-fuel/
     
  13. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
    thanks gents. There’s all kinds of crud on the turbulator (sp?) thing inside the bowl so it seems worthwhile to do

    Frank, I followed your treatment plan when we took ownership of the boat and after 4 racor changes finally ended up with pink fuel. They were completely black with visible algae strings, so someone didn’t handle the fuel properly in the past.

    since then we’ve had no issues and the vacuum gauges do not show any major blockage, but I do see the “junk” in the bowl
     
  14. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
  15. mrsrobinson

    mrsrobinson Well-Known Member SILVER Sponsor

    Mar 9, 2006
    Virginia, USA
    2001 Sea Ray 380DA
    3126 purring CATs
  16. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    2002 410DA
    Caterpillar 350HP 3126
    Ethyl alcohol is a no-no. You want to use propylene glycol in engines, that’s the west marine pink. They’ll take about 7-7.5g each

    as to why it’s not recommended, I’ve always heard it eats seals and rubber and such which there is plenty of in the raw water path. Whether that’s true or not, who knows
     
    Last edited: Sep 22, 2022 at 5:52 PM

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