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Practical Engine Building: Replacing Frost Plugs

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Replacing Frost Plugs


00:00 - In many instances, the frost plugs or freeze plugs as they're also known, that are fitted to the water jacket of the engine block, is an aspect that isn't given much consideration when it comes to the engine building process.
00:12 Particularly if you're dealing with late model engines and specifically those that have been well maintained, and by well maintained what I'm talking about here is a coolant that has been topped up and kept in good condition with a corrosion inhibitor, often the frost plugs will be in perfect condition and won't need to be replaced.
00:33 If you're dealing with older engines however, often the cooling systems won't have been well maintained and the frost plugs can be a source of water leaks so it's important to inspect these and replace them if there's any sign of corrosion or leakage.
00:49 In this module, we'll see first of all how to remove a frost plug from an engine block and then we'll see the correct technique for installing a brand new frost plug.
00:58 In this instance, we're going to be performing our demonstration here on a Toyota 1FZ engine block.
01:04 What we're going to do is start by removing this frost plug on the side of the block.
01:09 Now the technique for removing the frost plug is a little bit awkward.
01:12 What we actually need to do is hit the frost plug or punch it into the block, or into the water jacket, then we can turn it sideways and pry it out.
01:21 Depending on the condition of the frost plug and the block, sometimes this is relatively straightforward, particularly when we're dealing with brand new frost plugs like this, can be a little bit more work involved.
01:31 In order to do this, I'm just going to use a small diameter punch and I'm going to use a hammer.
01:37 What we want to do is hit the side of the frost plug and that will help tap the frost plug sideways into the water jacket and this will allow us to get a pair of pliers onto the frost plug to remove it, so let's go through that process now.
02:04 Now once we've got the frost plug turned sideways like this in the block, should be a relatively simple exercise to use a pair of pliers and manipulate it out and remove it the rest of the way.
02:16 So at this point we've got our frost plug removed, what we want to do is inspect the surface where the new frost plus is going to sit and particularly if the block has corroded, you're going to probably find there is a bit of rust and pitting in that cavity and what we want to do is make sure that we clean this up before fitting a new frost plug.
02:36 Now we can do that with some emory paper.
02:39 In this case because we are dealing with a brand new block, obviously we've got no corrosion.
02:42 What I'm going to do is just clean up that surface using some green scotch brite.
02:58 Now once we've cleaned down the surface we also want to just remove any remaining oil or debris using a little bit of brake clean and a clean rag.
03:08 So at this point we've got our surface cleaned up, we're ready to install a new frost plug.
03:13 Now we've got a frost plug here that we're going to be fitting.
03:16 This is a brass frost plug.
03:18 These are available in both brass and steel and it's important to understand as well that there are a range of diameters of frost plugs so we do need to make sure that we start by getting the correct diameter.
03:29 Now in order to install this, what we're going to be using is a socket, so this is the easiest way I've found of installing frost plugs and what we want to do is choose a socket that is essentially the same diameter as the frost plug and this is going to just give us a good surface that we're going to be able to use to gently tap that frost plug into place.
03:53 Now before we go and fit the frost plug we do want to apply some liquid sealant onto this.
03:59 So in this case I'm using a Loctite product, it's MR5923 and this is an aviation gasket sealer.
04:06 This is actually a liquid sealer so it's made specifically for tight fitting parts and we're going to just use this to help seal the frost plug into the block, so let's apply a little bit of that now.
04:25 So I'm just going to run a light bead of the sealant around the outside of our frost plug and that's just going to smear out across the surface as I install the frost plug into the block.
04:40 OK with our sealant now applied we can now locate the frost plug into the block and what I'll do is I'm just going to grab a half inch drive extension, just assemble that onto our socket around the wrong way and this is just going to give us something that we can tap against.
04:58 It's important while we're doing this to make sure that we make the frost plug square with the block so we want to tap it in gently and check our progress frequently.
05:17 Once we're getting close to having our frost plug installed, we just want to check how far in we've actually hammered that frost plug.
05:26 We can use one of the existing frost plugs as a bit of an example of how far in we should be going.
05:32 What we can see is that there is a chamfer on the edge of the block where the frost plug locates, this helps guide the frost plug into location and what we want to do is hammer that frost plug in until the end of the frost plug is just flush with the base of that chamfer.
05:48 So I've just got a little bit further to go.
06:03 So at this point, our frost plug's installed, I'm happy with the depth, I can just clean off any excess sealant and we're ready to move on with the remaining frost plugs that need to be replaced.

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