1996 Sea Ray Sea Rayder Sport Jet 120XR Help needed

Discussion in 'Jet Drives' started by September, Jul 27, 2012.

  1. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    First let me thank everyone for all of the great posts. I've spent a couple days reading. . .You guys are awesome and have provided some great help to people in need.

    I am a female. . . .Please Don't hold that against me. lol

    I recently purchased a 1996 Sea Ray Sea Rayder F-16 with a 120 Mercury Sport Jet.

    It takes it a couple minutes to plane out. . .So I started reading and I'm not sure if I have a problem or not. My water intake vent (guard) is missing one of the. Also sitting at the stern looking at the jet exhaust or output, where the drive meets the hull (in the shape of a square) there was a couple pieces of black plastic that were broken and sticking out. See Attached pic
    There is some type of gasketing around this area also. WHAT WAS THAT and is that letting exhaust water slip though and that is why I am losing some power? My max speed is only 35. I am going to take pics and try to post them or if you are willing to help PM me and I will send them to you. SeptemberColl [at] g mail dot com

    It is very hard to steer if my daughter is sitting in the bow. I had old Baja jet boat with big chevy engine before. No open bow so I am not familiar with this situation. Is this normal? Steering is easy any other time

    The Bendex sp? on the starter got suck down on me one day and with just a little persuasion I got it to come up. I haven't had anymore problems with it. Should I replace it anyway?

    THANKS so much!
     

    Attached Files:

  2. baeckmo
    Joined: Jun 2009
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    Location: Sweden

    baeckmo Hydrodynamics

    Hello September and welcome! Jet boats tend to have some "behaviour issues", most of them linked to the high thrust line and absence of rudder. By "thrust line" we mean the vector, in which the force from the propulsion unit is acting. The thrust from a jet is acting above the boat bottom, causing a bow-down trimming moment, while the opposite goes for a propeller below the bottom.

    This is the reason to the steering difficulties with an additional load up front in your boat; the s.c. lateral area of the hull (~projected "wet" side area) moves fwd with a bow-down trim. The result is like throwing a dart with the feathers first; the steering area is ahead of the center of mass and the vehicle becomes directionally instable. The boat must be operated and loaded so that it is running with a slight bow-up trim in order to be stable. at cruising speeds, you should have a trim, referred to the keel line of 3 to 4 degrees, depending on bottom deadrise. This gives the lowest drag as well.

    Next to the performance question. It is not possible to see any details in your pics, but generally, the jets are very sensitive to disturbances in, and around the inlet area during acceleration. No barnacles, no bent grating fingers, no plastic bags stuck anywhere, no air leaks from between hull and "ride plate" a.s.o. Also check that the reverse bucket is completely out of the nozzle outlet diameter in ahead position. If the boat is bought used, it might be wise to check the impeller. If you didn't get a manual with the boat, you can find it here:

    "motorka.org/doc/mercury/service_manual/jet/SJ90_120_95xr_831996r1/sec5.pdf" puuuh....

    Take a look there, then its easier to point your nose in the right direction!
     
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  3. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    another question

    The bendex was getting stuck down It appeared that the bearing was going bad in the starter. I replaced the starter with a new one, First try it worked then the bendex didn't want to raise again, I manually screwed it up and down a few times and now it hasn't gotten stuck again. Is this normal? Do I need to do anything
     
  4. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member

    September...Baeckmo was kind enough to spend a few minutes to help you- a "simple thank" specifically for him goes along way to having other members chime in.

    I know I and most others won't answer new posters who don't show some thanks for our efforts.
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I don't think a a thank you request is necessary, nor do I think it will prevent any additional posts. The lack of post, I think, is a direct result of the nature of the problem, which is difficult to speculate about without hands on or more pictures.

    As to the Bendix issue, sometimes upon disassembly, you'll find some burrs or dings, that are just enough to have the drive in one position or another. Check the shaft, the "unloader" arms, inside the gear, etc. Did you replace the Bendix with the starter, or just swap out the starter motor? If you did change the Bendix, was it a remanufactured or new unit? A rebuilt unit uses parts from several different starters, often they don't fit very well, especially if some wear is associated with them.

    In short it sounds like you have several issues at play and you might be able to sort through them, but a mechanic out for a "check ride" and a free beer on a Saturday afternoon, may yield a faster diagnoses. Missing and dragging in the water parts, can go a long way to causing some of the symptoms you've experienced.
     
  6. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    Thank you. I'm not fortunate enough to have a marina or shop near that will service my boat. Even though it's basically a Mercury engine they see the jet drive and say "we don't work on jet boats"

    The starter and bendex came as one part. So should we put the old bendex in the new starter? It has not failed to engage since immediately following installing it. And you are correct Being a girl especially I don't want stuck out on the lake
    All of your replies are greatly appreciated. I to learn from all comments.
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Again, was the starter a reman unit or a new piece? It's possible there was a burr on the newly installed starter and your fiddling with it, knocked it off (or something).

    Being a girl has little bearing, on how inconvenient it is to be stuck on a lake. Everyone here has wished like hell, they'd brought a bigger paddle or a wider brimmed hat, on these occasions.

    As to the other issues, I too have limited jet experience, though with most boats coming into my yard, the issues are pretty obvious within the first 5 minutes. I mention this because a good technician can see things within a few minutes, that make them look in all the "usual suspects". Just like a good car mechanic, that opens your hood and lets out a big breath, as they realize the motor hasn't seen any real service, in quite a while. They know what they're going to find, it's just the order and variety of things that changes. The same is true of your boat (most likely), so maybe a drive to the local big puddle in your area and talking to some of the mechanics (only the cute ones). Bring along some cookies or donuts, particularly chocolate, as most will give up their mother's S.S. number for these, especially on a Saturday morning, when they'd rather be out fishing or drinking beer. Use your girly charm, wear short shorts, whatever it takes, as we know how it works and I'm sure you do too. Guys are pretty much helpless around girls with cookies, donuts and sad story, while wearing short shorts, trust me on this. Lastly, look for the old crusty guy. He'll be the one not saying much, though you'll likely catch him staring at the cookies (if he's really old) or body parts (if things still function properly or has discovered ******). This will be the guy everyone in the shop asks the tough questions, about the project they're in the middle of bungling. He'll only spend a few minutes with you, but the 2 minutes will be more valuable than 35 with the cute ones staring at your butt.

    I'm not trying to be a sexist (okay maybe a little), but just pointing out that sometimes we have to use what we got. You see, I'm a butt ugly, skinny guy with big warts and similar disposition. I've had to pay dearly, often with blood and once with my first born (got him back on a "lay-a-way") to get difficult problems solved. Being a guy and having the pride and ego issues often associated with this affliction, you just can't imagine how hard it's been over the years, so I know you understand the realities and advantages, you have at your disposal. Yep, they'll try to take advantage, but I think you're way smarter than the average puppy they've seen, so should be able to weasel enough information out of them, to get your boat fixed, without having to date any of them.
     
  8. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    Thanks so much
     
  9. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    I wanted to post a little update...after personally seeing the acceptable tolerance between impeller and wear ring I now now that mine could use a little work. That might be why I feel as if there is a power loss.
    Now back to the starter. As I said before it will spin but not raise to engage the flywheel. I move it with a screw driver or pliers and try it again and she fires right up... Could it need greased? If so what kind. My old one appeared to have blue grease it in. Doing a google search I saw whee some people were being told it could voltage regulator or loose battery terminal. So could it just not be getting enough power to raise?
    Mercury sport jet 120 xr
    And I do greatly appreciate all of the help.
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The drive assembly on the starter (the part that engages the flywheel, often called the Bendix) works by electromagnetic force (solenoid). When the solenoid receives power, it sends electricity to both the motor and the the electromagnet drive gear/lever assembly. The Bendix gear is forced out to engage the flywheel teeth (usually a fork looking lever), by the activated solenoid. Once the engine starts and the key is released from the "start 2" position, the solenoid doesn't receive any more electricity and the Bendix returns back down the shaft.

    The Bendix should move easily up and down the shaft. You should be able to remove the solenoid and lever the folk assembly up and down manually. If this requires effort, then the shaft is bent or there are other problems with the starter or Bendix drive. To be honest, the Bendix is the usual culprit, assuming the solenoid is healthy. The forked lever can also be binding or have burs on it. Also the little collar on the bottom of the Bendix that the fork rides in could be warped or other wise not smooth, binding up the Bendix. Pull the starter and clamp it to a work bench or in a vice. Use jumper cables and a battery to make the starter work. The Bendix should jump right out without hesitation. If not, check for burs on the shaft, maybe try some grease (which it should have), examine the fork, the ring the fork rides in, etc.

    The reason I ask if it's a remanufactured unit is, they mix and match parts in reman assemblies and sometimes these don't work, as well as a new unit or a rebuilt unit using all the same parts from the same starter.

    Is it making a clunking noise when first engaged? This usually means the drive gear isn't lining up with the flywheel and you might need a shim or two. A ticking noise might mean the solenoid is bad.
     
  11. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    Thank you. The starter assy is new. But probably reman. We will try the bench test.
     
  12. September
    Joined: Jul 2012
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    September Junior Member

    Well didn't get time to test it!! Someone bought my boat.
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Beats buying a new starter too . . . congratulations.
     
  14. September
    Joined: Jul 2012
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    Location: West Virginia

    September Junior Member

    I had already bought a new one. They were both doing the same thing... Bendex not raising. I'm betting it was an amperage issue. Solenoid not spinning fast enough to "fling" bendex up. Now I'll never know. The starter would work 7 out of 10 times.
     

  15. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Solenoids don't spin. It's just an electromagnet, that once energized, pulls the folk looking thing on the bottom of the Bendix, to raise the cantilevered opposite end (which is attached to the ring on the bottom of the Bendix). Bad solenoids aren't uncommon, especially automotive replacements for marine rated pieces (they just don't hold up in a boat).

    Generally, I replace the whole shooting match if a starter is giving the ghost. The solenoid, starter and Bendix, as well as any questionable cables and connectors. On GM style starters, this is my usual course, but separate solenoids, like the Ford style, I usually check them be fore replacement. My logic being if the starter has seen enough cycles to spit up blood, the solenoid, connections and Bendix can't be far behind.

    Unlike a car, where you can stick out a thumb and get a ride back into town, when a part takes a dump, drifting along, farther from shore than I can swim back too, or towards the water fall isn't my idea of a good time, so the parts need a replacement schedule to avoid problems. Most of the parts I replace still work, but are "showing signs", which causes me to loose faith in them.
     
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