Found These Bolts

[ken52]

I was cleaning the inside the cowl area of a of a recent used S150 TXRX I bought and found these 2 long bolts.
Head- 10mm
Shaft-6mm
Length- 4 5/8"

Don't have a clue where they came from or belong. Nothing seems missing. Can anyone tell from the pictures. They have a dark finish like a dry film.

 

[JGM98467]

Re: Found These Bolts

I am no expert on outboards but I have been a mechanic for 15 years and they sure look like head bolts to me.

 

[Bob_VT]

Re: Found These Bolts

Look like shipping bolts to me. Are they stainless steel? If not then they are not part of the outboard motor.

 

[rodbolt]

Re: Found These Bolts

yamaha did not then nor currently use stainless steel much at all in any powerhed bolts.
lots of chrome plated but very very few stainless.
they plate them .
interesting though on the 4 5 eigths length.
cant think offhand of any 6mm fastener that long used on that engine.
efi motors used a similar bolt, but they were chrome plated ,on the throttle body to intake bolts.
to small to be head bolts on that engine, all the head bolts are 8mm.
to long to be water jacket cover bolts or T stat housing bolts.
airbox and ECU covers use screws.
gotta think on this one a bit

 

[ken52]

Re: Found These Bolts

They are steel bolts (stick to a magnet) that have a type of baked on non stick dry film. Seem to narrow for head bolts cause there thinner than a pencil.

I got nervous when I found them after buying the whole boat package(boat, motor, trailer) and missed them before that. They were kinda hidden away. They almost look like they were hardly used before, just a little wear about 1/4" under head. Both have under bolt head a small lock washer and a flat washer with same coating. Have no idea how long they were there.

I did compression check berfore purchase and all 6 were at 120 and motor ran great and pumped water through tell tale like nobodys business. I was actually surprised how strong the flow was when I put my hand into it.

Thanks so far for the help on this.

 

[TheFin]

Re: Found These Bolts

I think they are from the starting motor ??

Part number 14

http://www.boats.net/parts/search/Yamaha/Outboard/1999/S150TXRX/STARTING MOTOR/parts.html

 

[ken52]

Re: Found These Bolts

You are the MAN !! I can only assume that they backed out from vibration. Will have to keep my eye on them periodically. I stugged them up so they should be ok now. Can't see a mechanic taking them out unless he was rebuilding the starter. Thanks again it was driving me nuts where they came from.