Core Plugs in Head

[summerinmaine]

I'm currently replacing all the core plugs and the one at the rear of the head appears to be brass rather than steel. Should there be a difference? I can't see any reason why.

[Foxie]

I'm currently replacing all the core plugs and the one at the rear of the head appears to be brass rather than steel. Should there be a difference? I can't see any reason why.

Steel core plugs are cheap, but will rust out in time. (20 -30 years !) Brass plugs won't, but are more expensive. Brass coeff. of expansion is closer to aluminium than steel, so should be less risk of popping out.

[summerinmaine]

I'm currently replacing all the core plugs and the one at the rear of the head appears to be brass rather than steel. Should there be a difference? I can't see any reason why.

Steel core plugs are cheap, but will rust out in time. (20 -30 years !) Brass plugs won't, but are more expensive. Brass coeff. of expansion is closer to aluminium than steel, so should be less risk of popping out.

Thanks Sean!

Sounds like I'll do them all in brass then.

[ecamiel]

Brass and Aluminum in water form a battery - an electrolysis nightmare -

Stick with steel plugs.

Eric
64 S1

[summerinmaine]

Thanks for the warning Eric!

I'm going to pull all the plugs in the head in the next day or so, and I'll look to see if there is any discernible difference in the interior deposits. My understanding was that brass plugs came coated with a sealant, so I wonder if this is to prevent the battery effect.

[mikealdren]

Jim,
Afraid not, the sealant helps but the main seal is from the metal to metal contact as the core plug is driven in and expands to fill the hole..

Incidentally, I would have thought that a tell plug would also set up a cell but it's been far too long since I studied these things and I'm quite willing to accept that the voltage is greater with brass.

Mike

[summerinmaine]

Jim,
Afraid not, the sealant helps but the main seal is from the metal to metal contact as the core plug is driven in and expands to fill the hole..

Mike

So if I coat the orifice with gasket compound before fitting the core plug, I suppose the seal is so tight as to force its way through to achieve metal-to-metal contact, right? Ah well, I guess steel it is!