How To Remove and Fit a core plug

Here at Engine core plugs we have put together a quick how to remove and fit a core plug guide showing you some of the tools and a few tips to help any DIY home mechanics.

Dont forget to accurately measure the hole before checking what size plug your require. We have a handy imperial to metric sizing chart to help you.

Unfortunately, there is no off the shelf catalogue available for any engine core plugs sets. All the core plugs sets listed on our ECP shop have been created from scratch using engine data or engine and cylinder heads that have come through our workshop for repair.

Let us know if there is a kit you would like to purchase but is not listed, we would be more than happy to create a bespoke kit for your application.


Tools required:

Safety goggles

Ball pein hammer

Punch or old flat slotted screwdriver

Power drill and drill bit

Small pry bar

Water pump or vice grip pliers

In an ideal world the engine or cylinder head would be removed and on the bench ready for rebuild. To allow for good access to all the core plugs. If fitting with the engine or cylinder head in situ, access might be blocked by any number of different items in the engine bay. This could require removing of the items to gain access to the core plug openings.

The engine block or cylinder head should be drained of any remaining coolant before attempting to remove any core plugs

Cup Type

The easiest way to remove the original cup type core plug is to use a punch or flat slotted screwdriver on one side. The core plug spins in the opening making it easier to get a small pry bar or screwdriver behind it.

Dish Type

Dish type core plugs can sometimes have a solid lip that they butt up against. In which case drilling or piercing a hole in the plug and then using a bar or screwdriver is the easiest way to pry the plug out.


Tools required:

Safety goggles

Ball pein hammer

Flat round Punch


Power drill with wire attachments or small wire brush

Old sockets – slightly smaller than cup core plug you are trying to fit

And of course correct size core plug or core plug kit you are installing

Again because of various items in the engine bay it may not be easy to access the openings for the core plug to be installed

As with most automotive repairs, the area you are working on (in this case the core plug opening) must be thoroughly dry of any coolant and cleaned of any rust, old paint or localised debris before installing. It is also worthwhile using some sort of sealant to provide a guaranteed seal. High-quality sealants like Elring Dirko, Victor Reinz Reinzosil or Hylomar Blue is recommended but use only a small smear around the edge of the core plug.

It is also worth noting that some sealants take longer to cure than others. Check the curing times before refilling the coolant. Also be mindful of any leaks before and during running the engine up to temperature.

Cup Type

A cup type core plug can be installed with an automotive socket slightly smaller than the plug its self. The core plug should be a snug fit, making sure it is square in the opening and not crooked. Once positioned the socket can be gently tapped moving the cup core plug into its final position.

Dish Type

Dish type core plugs should be installed with the concave side facing inwards and the convex (bump) facing outwards. A dished type core plug will need to be positioned correctly in the opening and then given a sharp hit to the centre of the convex (bump) with a ball pein hammer or flat ended punch. The plug will then expands slightly sealing tight to the end of the opening. Sometimes the opening will have a lip which the core plug will sit against which makes it a lot easier to install.

That is the end of the how to remove and fit a core plug guide. As always please do not hesitate to contact us if you have any questions.