HELP: BOLT IN BILGE- '87 Donzi 18

[vlbob2]

SCAREY: After a ride yesterday (not particularly rough) a LARGE BOLT is in the bilge, between stringers, 3/8 x 3", 9/16 hex head, silver. An initial survey with flashlite & mirror did not find any obvious bolts missing from front of engine (350 sbc mag V8) ie; alt, ps, closed cooling brackets. I am not familiar with the starter bolts on sbc, nor what bolts hold on outdrive??? 3/8 x 3" being a serious size bolt, I'm hoping one of you engine/boatbuilders can identify...HELP! Thanks, Bob

[MOP]

Size sounds like a starter bolt or the alternator or power steering pivot bolts, or possibly a manifold bolt all of which are 9/16 and +or- 3", there are very few bolts that long!

[vlbob2]

Do you, or does anybody know exact dimensions of starter bolts on sbc to help narrow it down or pinpoint it? (boat is on a lift with starboard side out so access to starter is very difficult). What bolts are on outdrive?

[hardcrab]

check out motor mounts, any brackets on and around engine (?)

- could be superficial - , could it have traveled from another area and ended up at the engine area ?

[vlbob2]

Thanks, not engine motor mounts, not ps, not alt pivot, not exhaust manifolds... somebody must know?

[Walt. H.]

If its a starter bolt it will have serrations or knurling under the bolt head where there isn't any threads.
Your best bet is to start feeling around those area's asap because you don't want to start or run your engine with any of those bolts missing, as in ruining your engine flywheel teeth with a wobbling starter motor resulting in a broken starter nose cone at the very least or throwing a loose belt.

Alternator and P/steering bolt will be easy to spot if missing, check for loose belt will be a dead give-away...
Keep us posted as to what you find!
WH

[fogducker III]

Not sure of the size or length of the two bolts that hold the bell housing to the inside gimbal plate....???

[vlbob2]

Thanks, No knurling or serrations under head. Long shoulder as 2" of bolt is not threaded, only last inch. It is not ps or alt as I replaced alt last week (and had no parts leftover). As I recall, 2 bolts hold on starter? One of you sbc experts must know exact dimensions of starter bolts???

[vlbob2]

OK, I got over the water and upside down and could feel both starter bolts, the short one & the long one too! Now what? Any ideas?

[mrfixxall]

OK, I got over the water and upside down and could feel both starter bolts, the short one & the long one too! Now what? Any ideas?

post a pic of the bolt..

[vlbob2]

Wish I could but haven't figured out how to yet? 3/8 x 3" with 9/16 hex head, long shoulder threaded last inch only, sorry.

[mrfixxall]

Wish I could but haven't figured out how to yet? 3/8 x 3" with 9/16 hex head, long shoulder threaded last inch only, sorry.

if you just got the boat it coulld be a gofor bolt,one someone droped in the bilge and could not find it so they gofor another one..

[vlbob2]

Wish it were that simple, could be, but it is 3rd season with boat. Was not in bilge when I replaced heads winter 09, unless came thru hole under rear seat...

[hardcrab]

think outside the box;

it could'a come from some other location, where is the "upstream"?

[RedDog]

All I can say is I hate it when that happens...