So What is This Bolt?

[RedDog]

When I pulled my boat at AOTH, this bolt came through the bilge drain. It's stainless. The engine is a 1998 Mercruiser 502 Magnum MPI.

Any insight on where to look?

http://www.donzi.net/forums/attachment.php?attachmentid=36570&stc=1&d=1213146185

[BlownCrewCab]

I'm gonna say coupler to flywheel, although I thought it would have fine threads. Check your accessory brackets on front of the motor.

[MOP]

If it is a 1/4-20 it may be from the bottom flywheel water shield.

[Uncle Fester]

I vote for looking inside the bilge somewhere for a hole without a bolt...


Anonymous :) :)


Dam you... made me spit my beer on my screen :smash:

[Trueser]

Power steering / Alt bracket /

Always look for a hole. :wink:

Keep your chin up. Good luck on the water test.

[Ed Donnelly]

Oil Pan??????????????.....Ed

[BUIZILLA]

starter heat shield

[Tidbart]

I'll let you know what I find as I am putting my 502 together this week. I think MOP or Buizilla are on track. There are 2 small bolts that hold on a plastic shield around the flywheel. They are only mounted in a rubber grommet and will come out easily if the rubber dries out and cracks. Hey maybe that's why the previous owner kept lots of water and oil in the bilge.:doh::smash::shocking:

Bob

[RedDog]

it is 14-20 x 3/8

I looked at the parts schematics for the engine / transom assembly / pumps / etc for a 502 Merc / Bravo and didn't see anything that size.

Per the diagrams, the flywheel cover bolt is 1-1/4 long

schematics at: http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=824418+98 and http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809808+96

[BUIZILLA]

I have 4 stainless screws like that for the solenoid to bracket fasteners for the two trim/tilt solenoids and the slave start solenoid as well as two for the starter heat shield

[glashole]

have you done all of the work?

I know that i have a couple of spare bolts under my engine that are unattainable now after i dropped them because i don't fit far enough in

so until I get smaller friends or pull the engine or come up with some magnetic deal.......... :)

[The Hedgehog]

Power steering / Alt bracket /
Always look for a hole. :wink:
Keep your chin up. Good luck on the water test.

That is what I was going to say.

[Cuda]

I'm gonna say coupler to flywheel, although I thought it would have fine threads. Check your accessory brackets on front of the motor.
They aren't stainless steel either. I think they are a grade 5 bolt.

[Cuda]

have you done all of the work?

I know that i have a couple of spare bolts under my engine that are unattainable now after i dropped them because i don't fit far enough in

so until I get smaller friends or pull the engine or come up with some magnetic deal.......... :)
A magnet won't work if it's good stainless steel.

[ky-donzi]

1/4-20 3/8 long.... what ever it was it didn't need much to hold it there... probably a heat shield somewhere..... Being that it is that small.... probably wont cause to much damage...... When you find a 1/2-13 3" long then you get trouble.....

[gcarter]

Actually, I think the microfiche is incorrect (they DO make mistakes, ya know). I can't imagine that shield bolt being over 1/2" long.

[RedDog]

well I spent quite a bit of time in the engine compartment today with a mechanics mirror and couldn't find an empty hole. In fact, few of the fasteners are stainless - most are painted carbon steel.
I did manage to lose a 13/32 socket while repairing a busted ground strap on the transom assembly - hopefully it will bounce down to the bottom of the bilge.

[Pismo]

Does it still run well and not vibrate or do something else new, different and annoying? If not, don't worry.

[Tidbart]

Zoom in. It is circled in red. One on each side.

[RedDog]

Zoom in. It is circled in red. One on each side.

Wrong size and material? What you circled appears to be carbon steel (rusty) and per the diagram it is 3/8s in diameter

4 10-37612 SCREW (3/8-16 X 1-1/4 IN.)
4 10-32132 SCREW (3/8-16 X 1-3/4 IN.)

I have a 1/4-20 3/8 long stainless bolt

Pismo - since I found it I have only run it on the hose. I didn't notice any problems (yet).

[handfulz28]

Have you had that motor since new? I'm no expert and my experience is only with my '91 454MAG, but I don't think Merc is really big into using stainless bolts. I'm guessing '98 is a single serp belt? My '91 uses v-belts and I'm pretty sure that 1/4-20 is the bolt spec for my pulley bolts; but 3/8" length is pretty short.

The other locations I can think of might be fuel system bracketry, ECU/electronics brackets, shift/throttle brackets. At 3/8", a thin metal bracket is about all that bolt should hold right?

Last thoughts: if you haven't had the engine since new, someone could've replaced an OEM bolt with stainless. Could it be something non-engine related? Trim pump, tabs, battery mount? There's a better chance of those manufacturers using stainless hardware. But it still would be a bracket mount of some sort.

[DonziJon]

Back in the day, there was a famous sailboat racer who, when the occassion required a little extra edge, would wander over to the dock where his most serious adversary hung out, and casually drop a Cotter Pin on the deck of the guys boat just before the race.

Sometime during the race, the cotter pin would be discovered and everyone aboard would spend the rest of the race wondering Where the PIN came from and when the mast might come down. This would cause the skipper to lose some concentration and maybe give the other guy an edge.

This was all in the Spirit of competition of course. :smash: John

[RedDog]

Back in the day, there was a famous sailboat racer who, when the occassion required a little extra edge, would wander over to the dock where his most serious adversary hung out, and casually drop a Cotter Pin on the deck of the guys boat just before the race.
Sometime during the race, the cotter pin would be discovered and everyone aboard would spend the rest of the race wondering Where the PIN came from and when the mast might come down. This would cause the skipper to lose some concentration and maybe give the other guy an edge.
This was all in the Spirit of competition of course. :smash: John

That's It! I found the bolt at AOTH. Some dastardly fiend must have dropped in in while at the docks. Hummmm.... Trueser was docked next to me....

[Tidbart]

I have had the same size bolt sitting on the bench for the last week or so and I think I found its home.

See the bracket holding the dipstick tube to the head, just to right of the #2 exhaust port.

That is the only small 1/4" bolt on the whole motor. That has to be it.:yes:

Bob

[RedDog]

I have had the same size bolt sitting on the bench for the last week or so and I think I found its home.

See the bracket holding the dipstick tube to the head, just to right of the #2 exhaust port.

That is the only small 1/4" bolt on the whole motor. That has to be it.:yes:

Bob

I can't see what you are referring to in the pic, but I'll check out my dipstick this weekend. Thanks

[Tidbart]

Sorry about the photo quality. I zoomed in and circled the area. There is a small strap-type bracket just to the right of the exhaust port.

B

[Carl C]

I'd be wondering if any other bolts are loose. I found quite a few loose bolts while snooping around my engine room. I used up a whole tube of red loc-tite. No, a magnet won't work on SS but those long grabber tools work good for getting stuff back from under the engine.

[RedDog]

I have had the same size bolt sitting on the bench for the last week or so and I think I found its home.

See the bracket holding the dipstick tube to the head, just to right of the #2 exhaust port.

That is the only small 1/4" bolt on the whole motor. That has to be it.:yes:

Bob

Nope - that wasn't it. On my boat the one on the dipstick bracket is painted black and is still in place. My suspect bolt is stainless steel

[Tidbart]

I think you can safely say it is not from the motor. :wink:

B