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  1. #1

    Winter Service, Injector re-build re-tip, coolant filter add

    Heading down to the boat with the 15yr old driving, needed a distraction so figured I'd update this.

    On the list for this winter was a full tune up. Before we got ready for the tuneup procedure I ran a few tests on the engines, and really glad I did.

    These are 600hp 8v92 TI's

    The only real 'symptom' we had was port side of port engine egt was running consistently 50degrees F higher than all the other 3 egt sensors. Also, even after prop adjustment we were about 150 rpm off of our desired WOT loaded rpm of 2350. Also, coolant temps seemed to creep up slowly when running over 2100 rpms, which leads to the thought of being overloaded/overpropped or a mechanical issue being present.

    Both engines are about 300hrs off major overhaul. They start right up, little/no smoke and generally purr like kittens.

    Test #1 was to run the boat at 1500 rpm at the dock and take temps of all exhaust manifolds approx 1" from the heads. (as a disclaimer I do not know if this is an actual Detroit Diesel test, I just thought it would be a good way to isolate a possible issue by showing me the cylinders that may, or may not, be 'out').

    Here are the results from that test.
    Port
    Fore to aft
    1500 rpm
    outboard
    156 - 157 - 187 - 213
    Inboard
    188 - 167 - 195 - 120


    Stbd
    Fore to aft
    1500 rpm
    outboard
    205 - 193 - 235 - 197
    Inboard
    194 - 164 - 169 - 188


    There were more anomalies than I was expecting to find but the two that really stood out are the 120 deg on port and the 235 on starboard. The other variances were deemed 'reasonable' by a couple of old timers with detroit experience.

    After that test had isolated a couple of cylinders of interest I performed a dead cylinder test on the 120 deg port cylinder. When I pushed down and held the injector plunger down there was very little, if any, change in engine rpm. When I pushed down any other injector plunger on that engine there was a notable stumble which quickly recovered due to the governor compensating.

    So basically we were running on 7 cylinders (at low rpm at least) on port engine.

    At this point I decided that I would be pulling all 16 injectors and sending out for rebuild.

    I ran a bore scope up in the 120deg cylinder and can still see very fresh cross hatch hones, everything looks good. I'll be performing a cold compression test on it this week as well to rule out a bad valve.

    The injectors in my boat are 7125's which have 7 spray holes in the tip. The current injector for this engine is the 5670, which has a 9 hole spray tip.

    After some consultation on Boat Diesel I decided to also at this time have all the 7125 injectors updated to 5670's. The 7125 and the 5670 are identical in every aspect except the tips with the 5670 having 9 holes which is apparently for better low idle fuel atomization. Being that we spend extended times at trolling speed I figured it would be an appropriate upgrade/update.

    So all 16 injectors were pulled Friday night. It took approx 4hrs of labor (from me) and wasn't a bad project at all. I did end up with a couple of skinned knuckles and probably should have worn mechanics gloves during the procedure lol.

    The injectors shipped out this morning to RPM diesel in Ft Lauderdale for rebuild. If all other parts are good the bill should be $95/injector to rebuild our injectors.

    Other items on the list this winter are a couple of small oil leaks/slobbers, mainly on cover plates that will be addressed.

    Also we will be adding coolant filters on both mains and the generator. I ordered 3 filter heads today. No particular reason or symptom to make me add the coolant filters other than I run them on every other diesel engine I own and have been routinely amazed at what they pull out at filter change. Being that the 92's are wet liner I feel that coolant condition and cleanliness would be very important to longevity.

    https://www.dieselequipmentinc.com/p...iABEgK5lvD_BwE


    I'll update the thread as these projects progress.
    These use the same napa filters I use on my trucks/tractors, so it will be nice to have a filter common to all.
    Last edited by rustybucket; 11-25-2019 at 03:36 PM.
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

  2. #2

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    Rusty, think I remember you posted about an additional oil filter you had added or are about to.
    What is the brand because it probably is a project we would like to do. Looked online and Amsoil was all over the place.
    We are already moving the stbd engine fuel filter because you have to spin it off to change the raw water impeller, only took me 17 years to finally do it.
    CRICKET
    1966 HAT50C101
    Purchased 1985 12v71Ns
    Repowered 1989 with 8v92TI
    Repowered 2001 with 3406E

  3. #3

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  4. #4

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    Rusty, don't just replace the tips of the injectors, it's another $100 per but do the barrels and plungers as well. I have had them do a couple (m15) at a time as they become weak. Maybe mine costs more but they were $175/ea You should be good to go for several years unlike reliajunk's
    Last edited by ageless; 11-25-2019 at 05:01 PM.
    '88 55'C hull 394 ​BEATs Therapy
    12-71 TA's ZF BW190 1.5:1 gears

  5. Re: Winter Service, Injector re-build re-tip, coolant filter add

    RPM won't return an injector to you if it isn't in perfect condition.

  6. #6

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    Quote Originally Posted by Cricket View Post
    Rusty, think I remember you posted about an additional oil filter you had added or are about to.
    What is the brand because it probably is a project we would like to do. Looked online and Amsoil was all over the place.
    We are already moving the stbd engine fuel filter because you have to spin it off to change the raw water impeller, only took me 17 years to finally do it.
    I went with the Frantz triple stacker. I looked at the Amsoil and others and honestly they are all probably good enough. If I had cats or newer tech engines I'd probably go with the amsoil or one of the other newer tech bypass filters. It seemed like the Frantz triple stacker had a greater capacity for soot than the others I looked at. After all, the Frantz filters are the same era as my Detroits so they were basically made for these engines. The triple stackers were VERY common with long haul truckers with detroits. They are no longer produced so you have to find them used or new-old stock. I was able to find two new-old stock on ebay for a couple hundred dollars each. One of them is weeping oil on the t-handle so I'm going to replace all the seals in them with vitton this winter as well.

    This is not my image but shows a triple stacker next to a normal single stack bypass oil filter.



    The idea is the same as the coolant filter, it takes a small stream of oil (I tapped into one of the out plugs on the full flow oil filter), runs it through the triple stacker cellulose or synthetic filter media which filters it down to < 2 micron, removing all soot particles that the full flow filters completely miss, then I returned the oil to one of the plugs just above the oil pan. I believe these plug were intended for alternate dipstick locations.

    The cellulose media removes any moisture/water from the oil, the synthetic media will not remove moisture but has different properties, they slip my mind at the moment, but I think I'm going to be running 2 cellulose and 1 synthetic in each triple stack to get the best of both worlds. Currently I have 3 cellulose media in each can b/c that's what the filters came with.

    Some guys even stick a strong rare earth magnet to the side of the filter housing so that any metal particles are caught for inspection.

    We ran about 50ish hours with the triple stackers installed on the mains this summer and I was quite surprised. Usually after 15-20 hours I can feel the soot grit between my fingers when rubbing the oil from the dipstick. I can feel the oil now and it is still very slick, it is not gritty feeling like it used to be. It is still black, but perhaps not as black as it normally is, if that makes sense?
    Last edited by rustybucket; 01-29-2020 at 04:50 PM.
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

  7. #7

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    That is the head, it is integral with the bracket. The filter just screws on the bottom of that. The in/out ports are on each side.
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

  8. #8

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    Quote Originally Posted by ageless View Post
    Rusty, don't just replace the tips of the injectors, it's another $100 per but do the barrels and plungers as well. I have had them do a couple (m15) at a time as they become weak. Maybe mine costs more but they were $175/ea You should be good to go for several years unlike reliajunk's
    Quote Originally Posted by kelpy View Post
    RPM won't return an injector to you if it isn't in perfect condition.
    What kelpy said, after talking with RPM, and a few other people who have done business with them I am inclined to trust them. I told them to make them like new, and was told, yeah, uh that's what we do when we rebuild them lol. I have given them the go-ahead to replace any parts that are in need.
    Last edited by rustybucket; 11-25-2019 at 10:26 PM.
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

  9. Re: Winter Service, Injector re-build re-tip, coolant filter add

    They do good work there. If you take your injectors in and ask them to just change the tips, they will most likely just hand them back to you .

    I have all 32 of mine done by them every two years.

  10. #10

    Re: Winter Service, Injector re-build re-tip, coolant filter add

    Quote Originally Posted by kelpy View Post
    They do good work there. If you take your injectors in and ask them to just change the tips, they will most likely just hand them back to you .

    I have all 32 of mine done by them every two years.
    Curious, How many hours approx do you put on them in 2 years? Do you think a 2 year rebuild schedule is the way to go? Or should it be on an hourly schedule?
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

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