Butterfly bolts for engine impellor cover

[dunedin]

My previous boat had butterfly headed bolts on the impellor cover, which made it much easier to change the impellor.

Any idea where I could get these ? Engine is a Yanmar 3GM30 and the bolts / screws appear to be M4 with an 8mm thread length (10mm nominal size?). Not sure if these need to be s/s or another material for this purpose.

I have seen the speedseal, and may go this route. But the Spedseal is circa £50 - and only uses 4 out of 6 screws, plus knurled heads are more difficult to grip than butterfly (hence why most people seem to mention needing to use pliers, which is near impossible in Yanmar reverse layout)

thanks

 

[FWB]

Just a thought and I may be completely wrong but..... the Speedseal uses an O-ring and the standard fit is probably a gasket. So will you be able to tighten the wingnuts enough by hand to achieve a seal against the gasket?

 

[Lakesailor]

Any good? Wing screws

otherwise wind some wing nuts up a bolt to the head and weld the nut to the head.

 

[pvb]

You can get stainless wings screws from A2A4.

 

[boatbuilder]

If memory works I think you want pinwing.

 

[steveallan]

ASAP Supplies

 

[ColinR]

There is a kit. I dont know the details but i asked the engineer about it when he was doing the anual service and he fitted it so I can remove the impellor cover by hand. Mine is a 2GM20, I assume its the same. The engineer I use is a Yanmar agent, I dont think it was that expensive. colin

 

[jeremyshaw]

Speedseal.com has the kit for this. Butterfly bolts would be cheaper though..

 

[chasroberts]

Agree butterfly bolts would be cheaper but the good thing with a speedseal is that you can locate the two bottom bolts before placing the plate as they locate into a slot and not holes in the plate. This then holds the plate in position whilst you locate the other two bolts and tighten the lot by hand. This is very useful if like me you have to lean across the engine block and do the whole thing by feel alone. For the money involved it's well worth the convenience and it's also a a great customer service company. No connection just a satisfied customer.

Chas

 

[rogerthebodger]

A better arrangment IMHO is to screw some short threaded rod into the back of the pump bady. The backplate would then be located onto the studs and then wingnuts screwed onto the studs.

If the paper gasket was replaces by a rubber gasket about 0.5 to 1mm thick cut in the sane shape as the paper gasket. the backplate would seal with only finger tight wing nuts. The rubber gasket also being located by the threaded studs in the body of the pump.

 

[gianenrico]

[ QUOTE ]
Agree butterfly bolts would be cheaper but the good thing with a speedseal is that you can locate the two bottom bolts before placing the plate as they locate into a slot and not holes in the plate. This then holds the plate in position whilst you locate the other two bolts and tighten the lot by hand. This is very useful if like me you have to lean across the engine block and do the whole thing by feel alone. For the money involved it's well worth the convenience and it's also a a great customer service company. No connection just a satisfied customer.

Chas

[/ QUOTE ]

I second on that