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6V92's TAB lack of RPM

Discussion in 'Engines' started by Robertoman, Aug 30, 2015.

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  1. Capt Ralph, Sep 8, 2015
    #21
    Capt Ralph

    Capt Ralph Senior Member

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    Yep, I'd say there was a vacuum change.
    10s never had a chance.
    Snake oil is not going to fix that either.
    Keep rotating 30 mics and stay in the choppy water to keep the Sediment up.
    But I am afraid it's time for some tank polishing.
    Start asking about for a fuel tank polish/cleaner guy.
  2. Robertoman, Sep 9, 2015
    #22
    Robertoman

    Robertoman Member

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    I have the fuel polish guy polishing up his filters and he will be going to work soon.
  3. Capt Ralph, Sep 9, 2015
    #23
    Capt Ralph

    Capt Ralph Senior Member

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    That's going to smart in the pur$e but the best path.
  4. K1W1, Sep 9, 2015
    #24
    K1W1

    K1W1 Senior Member

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    Depending how much you have it might be cheaper to dump the fuel and replace it, use Biocide when you do either refill or reload the "cleaned" fuel
  5. Capt Ralph, Sep 9, 2015
    #25
    Capt Ralph

    Capt Ralph Senior Member

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    It is easier if the tank is low, I would not think disposing the fuel is required unless it's real old and not trusted. Your fuel guy can help determine this.
    Your vendor probably does not want to remove it all, need some to rinse the stuff from tanks bottoms and corners. This last fuel may end up dark. Some things ya can't filter out. You may want to dispose of this, Your fuel guy may have some better on site thoughts here also.
    On full or large quantities, our vendor is able remove it and store it close with a constant filter/pump running while he rinses your tanks.
  6. K1W1, Sep 9, 2015
    #26
    K1W1

    K1W1 Senior Member

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    If the cost of polishing it is more than the cost of replacing it I would suggest replacing it and cleaning the tanks. Dunno what was so confusing about my previous post.
  7. Capt Ralph, Sep 9, 2015
    #27
    Capt Ralph

    Capt Ralph Senior Member

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    The cost of disposing of the old fuel is more than the cost of new fuel. That more than doubles the price of replacing the fuel.
    He is on the left (West) coast. Under even more EPA regulations in removal, transporting and disposal of oil and fuel.
    In my hood, with a mobile business, I pay a fortune to dispose of used oil & fuel. I used to sell it.

    AND, You still have to clean the tank bottom and dispose of that.

    It may not be bad fuel, just dirty and dirty tanks.
    Last edited: Sep 9, 2015
  8. Robertoman, Sep 9, 2015
    #28
    Robertoman

    Robertoman Member

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    All good points. The boat had about 100 gallons of original fuel on board for sea trial. Age and condition unknown. Fuel bowls perfectly clean and clear. Boat ran well on trial.
    Exhaust seemed really loud and p/o assured that was because exhausts were totally out of the water. We added 250 gallons of (treated name brand) fuel and sea trialed again and found noise was not too bad with exhausts 1/2 submerged. (This was before i learned about the poor boy 10" exhaust silencers) which are on my, long, to do list.
    Ran a couple trips, noticed smoke, changed all filters and added restriction gauges on Racor Assy's, ran again, noticed smoke again and from info I learned here, decided that 2 micron filters were not good and filled tanks to top with more fresh fuel, added a biocide and changed racor filters to 30 micron and boat ran good. Whew, sorry for the long winded explanation.
    The point being, we now have about 3/4 fuel, 400 gal +- which is fresh, and treated. I could be wrong, but I thought that the "polishing process" just largely filtered the fuel and returned it to tank.
    I have worked with the polisher before and actually, never thought to ask.
    I don't want to throw all that red fuel away!
    But, all in all it has to be fixed, and we will see what happens. I hope I am not boring you all with my trials and tribulations, but I really get a lot from this sight and all the people here.
    I'll be back!
  9. Capt Ralph, Sep 9, 2015
    #29
    Capt Ralph

    Capt Ralph Senior Member

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    There we go. Your fuel guy will have two hoses into the tank (hopefully at two different places), one returning, another to pick up the crud. During the exercise, he will use the return to pressure sweep the bottom of the tank and start filtering the junk again. At some time he will make a report and ask to stop or sweep again and keep going. For my customers, I've always requested to keep sweeping till no more is picked up. This may near double the time but it's up to you and your check book.

    I have worked with the polisher before,, If your buds, then go over a game plan and expected cost subject to surprises.
    Show him the pictures you showed us. You of-course want that problem gone.

    We are blessed with a fuel guy in Jax that works with us very well for our customers. I help give him the access to the tanks and he does the dirty work. I clean up after him and put the ship back together.
    You may want to plan to make your fuel guys job quicker; Get everything (furniture, carpets, mother in law) out of the way. Open up the tanks sender opening and any service points he may need to access. He's on the clock to do it him self.

    The Californian (671TIBs) we manage has a tank astern under the master bed and two engine room beam tanks. The beam tanks have side mounted level senders (pains to remove). IM me if you have these and need help removing them.

    Again, your fuel guy may already know these things and if you want to help (save some pennies) he can guide you. Fuel tech guys usually don't want to move furniture, move bedding, or handle many things. You do not want him to transfer the odor of fuel to your stuff either.

    Keep us up on how it works out.
  10. Robertoman, Sep 28, 2015
    #30
    Robertoman

    Robertoman Member

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    Okay, here is the latest.
    The fuel guy came down and worked his a-- off, had to figure how to work around all the tank baffles to get to the bottom areas, He was very impressed with the amount of baffling, "these tanks are built like a tank". Filter and wash the tank, filled his primary filters twice with bugs and the third time about a 3 lb. coffee can full.
    He told me that I had made the right choice to clean. We only did the one tank at this time because there is no sign of problem in other side.
    I changed out both of the primary Racor's just for good luck and now to the boatyard to do the bottom.
  11. Capt J, Sep 28, 2015
    #31
    Capt J

    Capt J Senior Member

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    Change your secondary fuel filters on the engines as well as the Racors. I'd run 10 micron Racors and have a set of 30 microns as backups. If one side has a ton of algae and the other side doesn't, water is getting in there. Change all of your fuel fill o-rings and check your vent direction, make sure spray is not getting in there. If the dirty tank is the cockpit tank, then that makes sense as it is exposed to the sun and the heating up and cooling off.
  12. Robertoman, Sep 28, 2015
    #32
    Robertoman

    Robertoman Member

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    Question. When I last changed the spin on secondary filters, they were as tight as any filter I had ever loosened, two wrenches and they still collapsed!
    Is there a reason they need to be that tight, or maybe I am just getting old, seriously they were tight. I have changed a filter or two and these were tight.
    Is this a Detroit manly thing or what?
  13. dennismc, Sep 28, 2015
    #33
    dennismc

    dennismc Senior Member

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    You sure you are changing the fuel filters ? my secondaries are not spin ons, did not know there was a mod to change them, my oil filters are spin ons which was a mod.



    THOSE
  14. Marmot, Sep 29, 2015
    #34
    Marmot

    Marmot Senior Member

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    In the interest of technical accuracy, a vacuum of 12" of mercury is about 9 psia (absolute). The positive pressure created by a column of mercury 12" high is about 6 psig (gauge).

    A good place to start troubleshooting is to check the fuel pressure out of the pump, it should be max out around 60-65 psig. There are a number of reasons it might be low, the fuel filter is only one of them.
    Last edited: Sep 29, 2015
  15. olderboater, Sep 29, 2015
    #35
    olderboater

    olderboater Senior Member

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    You keep talking about the sea trial. Was there nothing in the survey related to this?

    Be sure the person who is "polishing" is really polishing and not just filtering. There are those who claim to polish by having a system of filters but have no centrifuge or other equipment to actually polish.
  16. Capt Ralph, Sep 29, 2015
    #36
    Capt Ralph

    Capt Ralph Senior Member

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    Are you putting fresh oil on the gasket before assembling?
    When spinning on, it stops and 1/4 turn more?
    The gasket swells when wet from fuel, it will get tighter.
  17. Capt Ralph, Sep 29, 2015
    #37
    Capt Ralph

    Capt Ralph Senior Member

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    There are updated mounts for oil and secondary filters to make them spin on. Even for the old Allison clutches. DDC used to sell an adapter for the block oil filters when it was part of the oil cooler. AC, Donaldson and others can provide new filter heads that exact replace the old cartridge head. If your tight with a Detroit shop, ask them to find you some used spin on sec fuel filter heads.
    Last edited: Sep 29, 2015
  18. Robertoman, Sep 29, 2015
    #38
    Robertoman

    Robertoman Member

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    As i stated in the title of this topic, I was asking for input regarding the rpm that these engines were able to achieve given the factors that were available to me at the time I asked the question.
    While on the original S/T the engines ran almost as they were supposed to, so given the conditions on that day, I concluded the engines were satisfactory.
    About a month later after a couple fishing trips when I went to "blow out the carbon" towards the end of the trip the best the engines would turn was about 1850+-rpm. That is what led to this topic.
    I don't know any other way to determine engine loaded performance other than to do a "SEA" trial. I don't think it would be liked much if we ran the boat around the ski course.

    Regarding the polisher, he is quite reputable and well known. No worries about his work.
  19. Robertoman, Sep 29, 2015
    #39
    Robertoman

    Robertoman Member

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    The filters I removed had been on since who knows when, and the guy who tightened them down never read the instructions printed on them (OIL and turn 3/4 turn after gasket contacts base), or he knows something that I don't.
    So you are saying, to spin filter on until it stops of its own friction, and then another 1/4 turn?
    Thanks
    Back in the day, I had an oil filter sealing gasket, pop out of the filter lost the oil at high load and knocked out the rod bearings and the crank in a CAT 1693, faster than I could shut it down. Long story short, that hurt.
  20. Capt Ralph, Sep 29, 2015
    #40
    Capt Ralph

    Capt Ralph Senior Member

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    There are usually a lil graphic or instructions on most filters. If the filter has instructions on it then that is what to follow. My comment was not to superseded any OEM instructions.
    However, when I spin on a secondary fuel filter, it's pre charged (almost full) with fresh fuel, oiled gasket and spun on till it stops plus 1/4 turn by hand. Never had a problem. Never had to wrestle another one off.

    I think the heat makes spin on oil filter seals expand more. I still hand tighten them but pull out the strap to get them loose a bit during changes.
    Last edited: Sep 29, 2015
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