VST screws insanely tight

[pstephens46]

They are not very durable either. 11 year old tank. I think heat may be out of the question with the fumes left over in tank. I was trying to reuse the gasket so I don't want to melt it. Aluminum corrosion on steel screws is probably the issue. There is one positive....The bottom of screw holes are exposed. I have doused with penetrating fluid. I am considering getting a can of the freezing spray.

[99yam40]

like most all of the fasteners on an outboard that is run in saltwater, they should be exercised and greased from time to time to keep them from sticking.

Good luck

[rodbolt17]

that is when a hand impact driver becomes your friend.

[DennisG01]

Make sure you're using the proper-size screwdriver bit - also make sure it is not worn (try a new one, if not sure). Put a good amount of downward pressure onto your driver to help keep it from slipping. Use a wrench or pliers on the screwdriver for extra torque (be sure to have lot's of downward force). You can still spray the PF from the top - it will usually still creep in - do it a few times over the course of a few days. If no joy, go for the impact... besides, do you really need an "actual" reason to buy a new tool? My wife buys new shoes for no apparent reason all the time.

[pstephens46]

Old school hammer driven impact screwdriver. I should have had one...
4 friggin stores and not a one....I know I can order from internet.

Needed it today. Maybe Harbor Freight...

[DennisG01]

Try the REALLY old school way... Push down hard and turn while you or someone else taps the top of the screwdriver with a hammer. Not ideal, but it can work.

[TownsendsFJR1300]

Plus 100 on the hand driven impact hammer tool....

Just make sure it's supported WELL when you whack it...

Paid for itself many times well over 30 years with the same unit..


If it has a round head sticking out, a small vise grip may work as well.

[pstephens46]

like most all of the fasteners on an outboard that is run in saltwater, they should be exercised and greased from time to time to keep them from sticking.

Good luck

Nobody digs into these things unless there is an issue. Well except Fairdeal, myself and most probably, head gasket Jason. If he had a VST....

Now I wonder, if the factory had treated these screws with anti-seize or grease, would it still have been effective after 11 years?

[TownsendsFJR1300]

Nobody digs into these things unless there is an issue. Well except Fairdeal, myself and most probably, head gasket Jason. If he had a VST....

Now I wonder, if the factory had treated these screws with anti-seize or grease, would it still have been effective after 11 years?

That's a moot question cause you know there never was anti seize
put on em. Job security for a Yamaha mechanic down the road...

Yamaha buried that thing so most would go to the shop..

You would think in 11 years someone would have serviced it, But in the real
world, probably not, especially if there weren't any issues...

[fairdeal]

it also doesn't help that you are using a "Philips" screwdriver bit -

which is actually designed to "cam out"


and those screws are "JIS"

whose matching bit is not

Google it.....

[cpostis]

it also doesn't help that you are using a "Philips" screwdriver bit -

which is actually designed to "cam out"


and those screws are "JIS"

whose matching bit is not

Google it.....

Yup, first time I pulled mine I tried a "Philips" that wanted to round out the heads. Stopped, looked close and found the JIS screwdrivers that fit tight and worked properly. Tight pressure and a bit of a twist and a tap busted them all loose with a pop (maybe I was lucky). Since the first time, maybe I pulled twice more. Tightened just enough to squeeze the tiny lock washers and let the o-ring type gasket do the sealing. I spray my entire engine w/Boesheild t-9 including these screws. Always easy.

Hozan JIS-4 JIS Screwdriver Set (NEW 3rd. Gen) New | eBay

[pstephens46]

I am betting no source for the JIS screwdrivers other than internet?

Should I attempt a good snack with an impact screwdriver tomorrow? Or say the hell with cleaning hp filter and reassemble the the whole mess and move on? Fully drained the VST today after removal and didn't see a damn thing but clean gas. Hex heads too much trouble to use I reckon.

[cpostis]

I am betting no source for the JIS screwdrivers other than internet?

Should I attempt a good snack with an impact screwdriver tomorrow? Or say the hell with cleaning hp filter and reassemble the the whole mess and move on? Fully drained the VST today after removal and didn't see a damn thing but clean gas. Hex heads too much trouble to use I reckon.

I'd want to check that hp filter.
Do you have the right bit for the impact driver that wont round your screw heads? Can you get a good straight alignment on your screws with the impact?

Up to you!

[pstephens46]

I'd want to check that hp filter.
Do you have the right bit for the impact driver that wont round your screw heads? Can you get a good straight alignment on your screws with the impact?

Up to you!

Find out in the am. I was able to verify the $110 check valve headed to silencer is working correctly. I suffer from the hot start issues often discussed around here....

[TownsendsFJR1300]

Soak em, support the VST where it's fixing to get smacked, and give it a whack. It'll go.

For regular work (no impact tool) the correct screwdriver is great to have.
Between the impact and force, it'll pop.

I don't own one JIS screwdriver (also used on small Honda engines), but the impact tool makes up for it...

I suspect they make "JIS" bits for the impact tool, but your much less likely to tear up the heads...


AND, being your that deep into the engine, I'd go the rest of the way and inspect...