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Practical Engine Building: Fitting Engine Bearings

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Fitting Engine Bearings

06.08

00:00 - Fitting the engine bearings into our engine block as well as our connecting rods, isn't an overly complex task, but there are a couple of key points that you need to keep in mind to ensure success.
00:11 First of all we need to be very sure that we're fitting the correct bearing shells into the correct location.
00:17 Here we have our main bearing shells for a Toyota 2JZ and you can see that the two shells are very different.
00:24 This particular shell is designed to fit into the upper location in the engine block itself, and you can see that we have two oil supply grooves machined into the bearing shell.
00:35 These grooves are designed to supply the oil to the crankshaft.
00:39 The lower shell which is designed to sit in the main bearing cap or the cradle, has no oil supply grooves machined into it.
00:48 Now if we get these fitted in the incorrect location, this can spell disaster as there will be no oil supply through to the crankshaft.
00:57 So that's our first key point, we need to identify the correct bearing shell for the correct location.
01:03 As with all of our engine building, we need to be very very careful with cleanliness any time we're fitting any components, and the same goes here for our engine bearings.
01:14 This starts with an inspection of the engine block, the conrods, and the main bearing caps.
01:21 What we can see here on our two main bearing caps, is we do have some signs of light corrosion on the machined surface.
01:29 Now depending on how extreme or severe that corrosion is, this can spell a problem, and this should be something that's going to be sorted out during the machining process.
01:40 However a freshly machined surface can quickly build some minor surface corrosion, and this doesn't necessarily mean it's going to be a problem.
01:49 A really easy way of removing some light surface corrosion, is to use something like this which is a green Scotch-Brite or scourer pad.
01:57 All we need to do is take the component that we want to clean and lightly scuff the surface with our scourer pad, and what this will do is just remove that surface corrosion.
02:07 If we can't remove the surface corrosion with some light work with a scouring pad, then this probably is something that's going to need to be addressed with our engine machinist.
02:17 Once we've actually removed any surface corrosion, the other thing we want to do is make sure that the surface in the engine block, as well as the bearing is clean from any oil.
02:27 In particular the engine bearings will be supplied with a protective film or layer of oil and we want to make sure we remove this before installing them.
02:36 All we need to do here is use a clean rag and some brake clean or isopropyl alcohol.
02:43 All I'm going to do is take the components that we're fitting and I'm just going to wipe over them with my rag as well as both surfaces of the bearing.
02:54 We want to be wiping both the front and back surfaces of the bearing.
02:58 Now it helps if we're using a clean rag here for this purpose as well, because we can actually see the results on the rag, we can see if we are still removing debris and material from the components we're cleaning.
03:11 Now once our components are ready for installation, we can actually fit the bearing into the bearing cap.
03:18 What I'm going to do here is take the bearing and we can see that there's a locating tang on the bearing.
03:24 Now this locating tang matches with the cut out or groove in our bearing cap which we can see here.
03:31 What I'm going to do is I'm going to start by fitting the locating tang into the bearing cap, and I'm just going to make sure that the bearing is central in the cap.
03:41 What we can see is that the bearing won't actually slide straight into the bearing cap.
03:48 There is a slight amount of crush necessary to fit the bearing shell into the cap.
03:53 Now the tendency here can be just to slide down on the bearing and push it home.
03:58 Now while that will work, what we tend to do if we use this technique is we actually scrape some material off the back surface of the bearing shell, and this can end up as debris that can pass through the motor.
04:12 What I'm going to do instead is I'm going to apply some light pressure in a forward direction using my two thumbs, and as I do this I'm just going to slide the bearing shell home and into the cap.
04:23 Now once that's done we can also inspect the parting surface between the cap and the bearing shell.
04:29 We want to make sure that there is no debris or scrapings from the installation of the bearing.
04:36 So in that case our bearing shell is now fitted into the main bearing cap.
04:42 Now let's look at the process being applied to the big end bearings into the connecting rod.
04:47 Now exactly the same process is applied, what we want to do is start by making sure our bearing shells as well as our conrod and cap are both clean.
04:57 So I'm going to do that now.
05:01 So first of all I'm going to start by just cleaning the journal of the connecting rod, just making sure that there's no oil, lubricant still remaining on that surface.
05:11 Next I'm just going to grab the bearing shell, and again I'm going to clean both surfaces of the bearing shell with my rag.
05:19 Once we've done this we're ready to install the bearing shell into the connecting rod.
05:23 What we want to do here, again grab the connecting rod and we're going to locate the tang, location tang into the connecting rod body.
05:33 And then this time I'm just going to use one thumb, and I'm going to apply inward pressure, and just allow the bearing to drop into location.
05:41 So again the bearing's home in the conrod body, and we can again inspect the parting lines, make sure that everything's OK there and we've got no scrapings from the bearing shell, no scrapings from the back of the bearing shell.