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SG Boater

Aluminum Locknut in Bilge, what does it belong to?

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Had our 210 out yesterday and was cleaning it up afterwards, getting it checked out and ready to head down to Bull Shoals lake at the end of the week.  Opened the hatch to check fluids, etc, and see a large nut in the bilge.  As you may know the engine area on a 210 is restrictive so got a magnet but it wouldn't pick it up.  So, got a shop vac and picked up an aluminum lock nut (with the nylon insert).  Fairly large, looks like 1/2" threads.  It's used as evidenced by threads in the nylon insert.  Engine was pulled in spring so I'm sure it was taken off at that time and didn't come loose on it's own since has the nylon insert.  And generally its suggested to not reuse lock nuts so I imagine (hope) a new one was used in this one's place and it just left in the bilge.  But I'd like to double check.  Any idea what it may have come from so I can check there is one there?  I checked, but can only poke around with a mirror so hard to investigate thoroughly.  Everything works as it should on the boat, but want to make sure this wasn't left off something important that could fail in the middle of the lake leaving me stranded. I will call the service shop that pulled the motor, but they're not open on Mondays.

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17 minutes ago, SG Boater said:

I will call the service shop that pulled the motor, but they're not open on Mondays.

That's probably the best thing to do.  Could be a  number of things and hard to guess.  Although a nylock would probably be for an area that doesn't get too warm, and since the motor was pulled and the nut is 1/2" diameter?  I would check the motor mounts first.

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Google didn't bring up anything 1st time, but second time around I found it is indeed one of two nuts that go on the two bolts that mount the engine to the transom plate.  Now that I know where I'm looking, will check it out and make sure one is on both bolts.    

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42 minutes ago, SG Boater said:

Google didn't bring up anything 1st time, but second time around I found it is indeed one of two nuts that go on the two bolts that mount the engine to the transom plate.  Now that I know where I'm looking, will check it out and make sure one is on both bolts.    

Ah, that's good.  I'm gonna bet that it probably either fell when they were remounting the engine (if it is indeed the nut for the engine mount) and they didn't bother trying to reach for it way down in the tight, back bottom of the bilge and just left it there and used another one.  Then it trickled forward to where you saw it.  I highly doubt they would forget a nut to an engine mount, although stranger things have been known to happen.  Let us know. 

What year and engine type?

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Those are stainless steel poly nuts, and most also have a tab washer that gets bent up after installation to prevent exactly what you found. If it's from a front motor mount then the engine alignment will need to be rechecked as the top nut is a jam nut and the lower nut may have worked it's way down. No weight on that nut when engine torques so in may have worked it's way lower. If it's a rear nut as you suspect, a simple re-install should cure the issue. This assumes that the fiber vibration isolator within the transom mount is intact. If it has failed, then that could be the reason the bolt worked it's way loose in the first place. In that event the drive comes off, the engine gets lifted slightly, mount replaced and the final assembly gets an engine alignment. W

 

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Wingnut, the rear mount nuts are aluminum, correct?  Looking on line it appears it's 1/2 x 20 thread, part # 11-863332.  I know the front mount nuts have the tab washer, but can't even see the rear nuts.  I'm going to have to pull the rear seats tonight and hopefully can see back there through the access ports.    I would bet like Hatem says, it was just dropped on installation and another used, but for peace of mind, I want to see a nut on those bolts.  FYI, it's a 5.0 MPI mated to an Alpha.

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Probably dropped while removing the engine since you stated "It's used as evidenced by threads in the nylon insert"... 

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I was thinking they were closed on Mondays, but not.  Talked to the tech that did the work and he said he did drop one, though not sure I trust his memory from 4 months ago after working on countless boats since then.  I assumed he'd pull the ticket and see if he'd charged one to the job cause that's about a $5 nut.  Hope his memory is better than mine.  He went on to say that if those two mounting bolts weren't snugged up and tight like they s/b due to a nut being gone, I'd know it through grinding and other unpleasant noises from I assume miss-alignment or simply the back of the motor being "loose".  Boat is smooth as silk, no vibration or any sounds out of the ordinary.  Sound right?  Reasonable to say I'd hear something if it wasn't right?  I'm trying to avoid pulling the rear seat to visually verify all is like it s/b, especially since I'm not even sure I'll be able to see it then.  I've put 25 hours on it since the work was done to it and like I said, runs smooth as silk.

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3 minutes ago, SG Boater said:

I was thinking they were closed on Mondays, but not.  Talked to the tech that did the work and he said he did drop one, though not sure I trust his memory from 4 months ago after working on countless boats since then.  I assumed he'd pull the ticket and see if he'd charged one to the job cause that's about a $5 nut.  Hope his memory is better than mine.  He went on to say that if those two mounting bolts weren't snugged up and tight like they s/b due to a nut being gone, I'd know it through grinding and other unpleasant noises from I assume miss-alignment or simply the back of the motor being "loose".  Boat is smooth as silk, no vibration or any sounds out of the ordinary.  Sound right?  Reasonable to say I'd hear something if it wasn't right?  I'm trying to avoid pulling the rear seat to visually verify all is like it s/b, especially since I'm not even sure I'll be able to see it then.  I've put 25 hours on it since the work was done to it and like I said, runs smooth as silk.

He's probably right, the engine will vibrate quite differently than "silky smooth" running.  I would check it anyway.  Get full peace of mind.

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2 hours ago, SG Boater said:

Wingnut, the rear mount nuts are aluminum, correct?  Looking on line it appears it's 1/2 x 20 thread, part # 11-863332.  I know the front mount nuts have the tab washer, but can't even see the rear nuts.  I'm going to have to pull the rear seats tonight and hopefully can see back there through the access ports.    I would bet like Hatem says, it was just dropped on installation and another used, but for peace of mind, I want to see a nut on those bolts.  FYI, it's a 5.0 MPI mated to an Alpha.

What year, make, and model engine?  W

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'05 Merc 5.0 MPI with Alpha drive.  I'm going from memory on this cause only had a few minutes this a.m. to look after I figured out that it appears to have come from the motor mount.  I can only see using a mirror, and even then takes a while to find those two bolts.  I found the port one first and head of bolt appeared to be up about an 1" from the mount so I'm immediately thinking the nut had come off that one and it backed out.  Then found the other and it was up also.  Didn't look like as much as the Port head, but again I'm looking at it through a mirror and at an angle.  But the heads of both bolts seemed to sit up more than I remembered on past boats.  Can't recall how the head of the bolt was in relation to the spacer, ie. sitting against it, or ?? And my recollection of past boats is pretty hazy.  Never had to deal with the mounts so only caught them at a glance when greasing the coupler.  

 

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You're probably fine if both mounts looked similar.  If you were missing one of the rear motor mount nuts, you would probably not only feel it, but you'd see the back of the motor shake, rattle and roll.  And if you were missing both nuts, motor would probably cone up out of the hatch, certainly not run silky smooth. 

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I would imagine you're 100% correct.  It's the OCD in me.  Ran home at lunch and double checked.  Both sides, head of bolt is about 1/2" or so above the flanged spacer.  I was thinking the head rested on top of the spacer, but as i said, i only looked at that connection in passing in my other boats, never paid any real attention to it because didn't have to worry about it.  

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14 minutes ago, SG Boater said:

I would imagine you're 100% correct.  It's the OCD in me.  Ran home at lunch and double checked.  Both sides, head of bolt is about 1/2" or so above the flanged spacer.  I was thinking the head rested on top of the spacer, but as i said, i only looked at that connection in passing in my other boats, never paid any real attention to it because didn't have to worry about it.  

Wait what!?  Why is there a space between the head of the bolt "e" on top and the washer "f"?  Isn't the head of the bolt supposed to be snug against the washer and that, snug against the flange spacer? That would mean it's loose and popping out by that 1/2". 

And where is the nut in that diagram?  Unless the bolt is threaded through that lower transom plate mount itself and you don't need a nut? 

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That's my concern.  I too would have thought it would be snug, but am not familiar with this connection.  Perhaps that's how you are able to adjust slightly? Both sides are pretty close to the same.  Starboard doesn't appear as much, but could be the angle I have to look at it.  The nut is down below "d" based upon another diagram I saw where you can order the nut.  I didn't try to verify by feel if a nut is there yet, need to change into some grunge clothes after work.  Tech did say some gap was OK.  Not 100% sure I was clear in what I was describing.  But I like you find it hard to believe both sides would back out the same and have the engine still run smooth.  Just looking for peace of mind..  

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Just called the tech a second time and he said it's ok for there to be a gap between head of bolt and washer.  And he said no way to see the nut, it's up in a recess in the bell housing.  I think I worry too much.  But I tend to do that when it's something I don't know much about.  

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8 minutes ago, SG Boater said:

Just called the tech a second time and he said it's ok for there to be a gap between head of bolt and washer.  And he said no way to see the nut, it's up in a recess in the bell housing.  I think I worry too much.  But I tend to do that when it's something I don't know much about.  

Huh, interesting.  Well, that's good then.  1/2" space just seems like a lot, and I thought that any needed play for movement is in the rubber spacer and not between the head of the bolt and spacer.  That means that either the washer is just bouncing around within that space or the entire bolt is moving up and down 1/2" but that shouldn't be the case with that lock washer below.  That should prevent the bolt from moving down and the nut from moving up.  I guess the entire engine mount is allowed to bounce within that space.  That seems to be the case, I guess.

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Hopefully someone that is intimately familiar with this connection will chime in.  Not sure if I really remember this, or if it's the power of suggestion but now it does seem vaguely familiar that the head of the bolt wasn't against that washer in my 1830.  I do know for a fact that I remember thinking it looked a little weird, but can't recall if I just thought it was weird to have a spacer between the head of the bolt and mount (why not just use shorter bolt if you're snugging it up) or if it was because the head of the bolt wasn't touching the washer/spacer?  

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Maybe this helps??

1_32e6cbdd-eeb1-4094-a605-4050c1bb9e75_l

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13 minutes ago, Wingnut said:

These are front mounts. Rear of the engine flywheel housing hangs off the transom and is bolted down from the top. I suspect what he has will match the below sketch. W

http://www.marinepartsplus.com/catalog/mercruiser/serial/5.0L_MPI_ALPHA-BRAVO/884717007/15044-160

Oh OK. I  thought SG was referring to the front ones.

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Mine matches Wingnuts sketch.  Correct for the head of the bolts to have space between them and the spacer/washer?   Ie, see my post about 10 above with the sketch.

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Yeah.  See it on my laptop. For some reason the diagram didn't show on my phone. My bad...

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