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Difference between port and starboard engine

Discussion in 'Technical Discussion' started by Worthy vessel, Sep 8, 2020.

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  1. Worthy vessel

    Worthy vessel Member

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    I had posted recently about my port engine transmission running 14 degrees hotter than the stb
    This is at cruise after about 10 minutes and does not change after that.
    I now realize that the port engine burns very slightly more fuel than the stb, at the rate of about 2%,
    ie: maybe 5 gallons more over 200 gallons of burn.
    I have a Sea Ray 36 Sedan Bridge with Cummins 380 hp. year 2009.
    The oil samples are good, the engines both run a constant 175 degrees.
    Question- is it possible the port engine is less efficient and transmission a little hotter because of the counter rotating prop?
  2. motoryachtlover

    motoryachtlover Senior Member

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    My port transmission runs a little hotter than stbd and was told this was normal due to it having an extra gear to turn in reverse. I don’t know about the 14 degrees but that sounds right. I am not a mechanic but went through this same drill this summer ironically leaving Sarasota heading south. I don’t know if the gulf was abnormally warm this year or not.
  3. alvareza

    alvareza Member

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    My two gears have a similar difference to what you describe. Engines steady at 164 degrees. I haven’t worried about the difference in transmission temp/pressure between the two since it does not seem to fluctuate.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Extra drag, internal or external, will easily change the gear oil temp. Also may increase some fuel consumption (talking near micro amounts here).
    If this is a new symptom, check your running gear. A lil whack on a blade, even if you can not feel it will do this, or simple fouling on one side.

    Some clutch / gear use an additional gear, Some just engage the other clutch but it does take some energy to reverse rotate the torque and may make some extra heat. Even here, should just be a few degrees,
    What gears do you have?
    Probably TD 5114s. Should be within 2-3 degrees if detectable at all.
  5. alvareza

    alvareza Member

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    Mine are MG5114A. Maybe I should be concerned. I will make a note of temperatures and pressures next time I go out.
  6. Capt Ralph

    Capt Ralph Senior Member

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    Put an IR gun on the same points between the gears. The same 5114s will take near 1000HP so don't worry. They are great clutches.
    However, Temp gauges are not made so well.

    Now, is this a new symptom or always been for many, many hours?
  7. cleanslate

    cleanslate Senior Member

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    Boats never use to have Trans/clutch temp. gauges, none of mine do whether it's the Borg-Warner or my Twin-Discs. I just have pressure gauges for the Twin-Disc units form 1981. Put tape over the temp gauge so you can 't see it ! Lol:) As long as the pressure is up, and you check and change the gear oil and clean the screen regularly you are good to go. To much info. and just another worry/distraction to bother you while at the helm, in my opinion, but nice to have I guess.

    Do a search on you gears on line. You should be able to find the factory operation manual on-line and that will answer your question about the temp range your gears can run properly with out causing damage.
  8. alvareza

    alvareza Member

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    It has been this way since I got the boat 2-years ago. Curious, so I’ll check temperature and pressure and compare to the manual.
  9. Capt J

    Capt J Senior Member

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    Are you sure your generator is not drawing fuel from the port tank? It could be any number of reasons, but Port gears always run a tad higher than starboard 9 out of 10 times. What temperature is the gear oil running at. It could be a list that causes un-even load. Could be that one prop has a tad more pitch.......Few boats run the exact same load factor......1-2% difference from side to side is good.....but I've seen as much as 7% on new yachts. Quite honestly it is most likely a non issue if the fluid is at the correct level.
  10. Worthy vessel

    Worthy vessel Member

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    Temps run port- 134 Stb- 120 Fahrenheit
    Gen runs off Stb tank so can't be the issue. I most run without generator running. Only go between 5 and 25 miles.
    Thanks for all the responses. What a great resource!!
  11. Capt Ralph

    Capt Ralph Senior Member

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    Your rite close to the line to need and check this out.
    But; you are NOT running hot.

    Lets get an IR gun on the two clutches while operating. Remember to put the dot on the same exact location at the same distance (closer the better) when comparing between the clutches.
    Include the oil lines to the cooler very well.
    Cleanslate had a good point above; without these later boats having clutch oil temps available, all would sleep better.
    We could just be chasing a wraith or bad sender / gauge.
    Or, Just the way it is (cue Walter Cronkite).
  12. Capt J

    Capt J Senior Member

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    How are you running the engines? Is there a synchronizer? or Are you pushing the throttles forward and running off what the tachometers are reading? Analog or digital tachometers? If you have the analog Faria tachometers that Searay loved to use back then, those tachs are usually very far off. It's also possible that you are running the port engine at a slightly higher RPM than starboard and the port is seeing a higher load factor and higher temp. You can buy a photo tach pretty cheap and put the tape on the shaft and see actual rpms at cruise on each shaft. 134F isn't enough for me to worry about IMO. There also might be something stuck in your gear oil cooler, easy to take the hoses off and check with a flashlight.
    Last edited: Sep 9, 2020
  13. mapism

    mapism Senior Member

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    Good suggestion.
    But unless hard to "see", due to how the engines are installed and how much space there is around them, I'd rather put the tape on their flywheels.
    Two reasons: allows to check also idle speed with no gear engaged, and avoids any gearbox reduction math.
  14. rtrafford

    rtrafford Senior Member

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    Temp guns aboard are critical tools. I keep two, just in case. I take various measurements while running long legs and log them in the ships log. Carry the phone camera and gun through my rounds, grab a video, and later transfer that information to the spreadsheet. Really want to spot trends early. A recent one help me find a failing cutlass bearing long before it could become a crippling issue. Heat guns. Love them.
  15. rtrafford

    rtrafford Senior Member

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    Just a thought, keep in mind that gear temps and fuel variation may not be a component of the same issue. Another place to check is to spin the wheels, be it at the shaft or in the water at the props. See if the shafts feel the same with regards to drag or restrictions. Alignment issues or a bad bearing can cause the fuel issue as well.
  16. Capt Ralph

    Capt Ralph Senior Member

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    Flywheels? SAE 1 & 2 flywheels are enclosed. The front pulley or harmonic balancer is where to read from. However, just to ensure the engines are turning the same speed and the exact rpm is not an issue, as J's post is concerned here; the shaft coupler works fine.
  17. Capt Ralph

    Capt Ralph Senior Member

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    Get the Ap that allows your phone camera to to show heat sigs. Un-calabrated with out a proper sender, but it shows a thermal of the image.
    I use this for quick battery issues. Amazing how fast you can determine a bad cell while charging the bank.
    Yep, out of 16 cells on my 32V bank, I can see who is charging and what cell is bad.
    Great for un-calabrated spots on exhaust manifolds; What lung is weak, NOT HOT.

    Yep, a bad 19" 8V battery on JoSea. FM
  18. mapism

    mapism Senior Member

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    Guilty as charged for using the wrong term, indeed the pulley is what I had in mind when I wrote flywheel.
    In fact, my comment about being possibly hard to reach only makes sense for the front pulley, not for the flywheel side, by the way.

    But talking of terminology, what do you mean by shaft coupler?
    If it's the shaft connecting remote gearboxes (those which usually integrate a V-drive), not all boats have that transmission layout.
  19. Capt Ralph

    Capt Ralph Senior Member

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    Either straight drive or V drive, Reaching the shaft may be tough. The shaft coupler, is that big round thing that joins the shaft to the transmission output flange. It may be more easier to place a piece of tape on the coupler, and observe with a photo tach.
    Regardless of where the foil tape is placed, just the same place on both engines if just comparing rpm.
    If your checking against your helm tach, Best on the balancer or crank pulley base.
  20. Capt Ralph

    Capt Ralph Senior Member

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    Also in Skippy J's post #12 he mentions tachs not reading the same.
    I remember a customer who constantly complained about a noise in his boat while cursing that drove him near crazy. Finally I went for a ride, he opened her up on plane, settled down to a easy cruise and there was the sound.
    I reached over and just tapped on the throttles to bring the engines in sync by my ear. Noise went away.
    Cat 3126 and big VDO tach are used on other SleRays also and these were off.
    The owner was so proud that he could quickly get the tachs to match each other, he never thought they were in error.

    Learned a lesson in replacing the tachs. I thought I would just purchase one new VDO tach and tie the 3 (2 old, 1 new) together and find the tach in error. Well all 3 read different. The new tach was verified to be correct.
    I had to purchase a second new tach and it did match the first new one.
    Oh, New VDO tachs do not have the tacky SleRay emblem in them.

    So, keeping a long story long; If your syncing up with the tachs on the dash, regardless of mfg, they could be wrong.
    Just takes a couple of rpm to make one engine do more work, use a few drops more fuel, more wear and maybe more heat.
    Or think of it another way, just a couple of rpm off and the slower engine is dragging,, slowing the boat down.