What are these holes on my manifold and risers?

[tony1b2000]

Hi,

Just received my manifolds and risers. I am noticing several silver plugs to cover holes in my manifolds and risers. Are they permanently in there (sealed) , or do I have to remove and put a threaded plug in them? Sorry if this seems like a stupid question. This is my first time changes these myself!

See pictures..

Thanks

 

[electricaldoctor]

Could they be frost plugs?

 

[scoflaw]

My new set had them too. Core plugs like the block I guess, something different for sure.

 

[tony1b2000]

My new set had them too. Core plugs like the block I guess, something different for sure.

Did you just leave them in there? No leaks?

 

[Blueone]

Core plugs... Common in a complex casting. They are press fit in, nothing to worry about

 

[tony1b2000]

Core plugs... Common in a complex casting. They are press fit in, nothing to worry about

Thanks All! Odd the original ones in my boat don't seem to have them.

 

[Bt Doctur]

what motor are they going on, being a big block

 

[Blueone]

Your original castings were in production and cored differently to avoid core plugs because they add cost. That casting you have looks like it was a lost foam process because of the texture and the glue lines. So it's aftermarket or service. To keep the foam from floating or moving around they come thru the wall to support it and then plug the hole after. The production mold process was expensive and wears and not efficient for low volume.

 

[tony1b2000]

what motor are they going on, being a big block

496 mags

 

[tony1b2000]

Your original castings were in production and cored differently to avoid core plugs because they add cost. That casting you have looks like it was a lost foam process because of the texture and the glue lines. So it's aftermarket or service. To keep the foam from floating or moving around they come thru the wall to support it and then plug the hole after. The production mold process was expensive and wears and not efficient for low volume.

Thanks
The risers are OEM and came in a Mercury box, the manifolds are Quicksilver which I thought is merc, just sold through a non merc dealer

 

[Blueone]

Mercury is a leader in lost foam ....world leader in aluminum lost foam.... There are a lot of ductile iron lost foam foundries in China, Mexico and South America that merc will outsource to... They would meet merc specs and merc would call it their parts. You have nothing to worry about.

 

[joeyleggz]

My brand new mercury exhaust had the same casting plugs freaked me out to , after about 80 hours I noticed a slight what I thought was a trickle of rust but it might’ve just been condensation Spoke to Mercury direct and said not to worry none of this should pose a problem ,they should’ve made those brass instead of steel

 

[joeyleggz]

I was actually thinking about covering them with some Mercury engine paint

 

[Blueone]

They are steel so they expand and contract with the ductile iron as the casting heats up and cools... You could paint them to help with condensation rust

 

[LG111]

They are freeze plugs like on your engine block. In the event the manifold has raw water remaining in them during the winter and the freeze expands the plugs blow out and save the Manifold. Save $1.00 vs buying a new manifold for $600.

 

[Blueone]

They are freeze plugs like on your engine block. In the event the manifold has raw water remaining in them during the winter and the freeze expands the plugs blow out and save the Manifold. Save $1.00 vs buying a new manifold for $600.

This is not true and will give a false sense of security to a person not winterizing properly.
Production cast iron engine components that have sand cores to shape the internal passages of castings sometimes need to be supported during the casting process and need the sand removed and internal passages shot peened to clean the sand and coating removed.... if core support is needed and if there are blind passages ..access holes are made for this purpose. That is why you see the cup/core plugs. Today the holes are held to a tight tolerance and an industrial loctite is applied to the circumference of the plug and it is pressed in place.. This has been the practice for years and quite safe.

Lost foam that doesn't have sand cores needs the foam supported during the pouring of the metal... So you need the holes for that and then plugged.

 

[scoflaw]

Checked mine with a magnet and they're SS.