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Rebuilding the Cylinder Head on a 4-Stroke Outboard

In this video I rebuilt the cylinder head to a Honda Outboard. This involves reinstalling the valves, valve springs and camshaft.

Rebuilding the Cylinder Head on a 4-Stroke Outboard – Video Transcript

Hey there Dangar Stu here. Today's video is about reinstalling the valves and camshaft into this Honda outboard cylinder head and is proudly sponsored by MarineEngine.com.

This outboard had a blown cylinder head there was quite a bit of water in the bottom cylinder and as a result the valves from the bottom cylinder looks like this too. It's not super healthy but the whole lots been off to get machined so the actual edge is here are now fine. Where the valve touches the cylinder head or exceeds. And the head itself has been machined and everything as well so. Time to put it back together.

To do this job I've got a set of these which are the valve stem seals. So, we'll put new valve stem seals in as we go. We're also going to be using a simple spring compress like this to install them. Before we get started I'll just give you a quick look over the cylinder head. This is the top of the cylinder head. These are the holes for the head bolts and these are the holes where the valve stems are going to come through and then on top here is where the camshaft lies.

Around the side here we've got the holes for the spark plugs and then on the bottom you can see here's where the spark plugs come through into the cylinder head and here's where the valves are going to be seating against. Intake manifold bolts on here and this is where the exhaust comes out. You can see here also that the valves are two different sizes the larger ones the intake valve the smaller one is the exhaust valve. First thing I do is just put a small bit of pre-assembly grease on it. That makes these things a little bit easier to install to push through the stem seal and also means that when it starts up for the first time before you get full oil pressure you know you don't have any sort of wear in that early startup phase.

I've just had a bit of a play with the first two just to figure out which top works on the end of the compressor. So, the compressor comes this one anyway like this this is a winding type yet lever types all different types but this particular one seems to work pretty well. Because a little spring seats fit inside here I can show you and it kind of captivated inside this little lip here. So, this particular fitting seems to be working best for this outboard. I'll bring the camera over now and just point down and show you and we'll do the other end here the ends are a bit easier because I can kind of hang the cylinder head off the bench a little bit and get the tool round both sides.

So, we'll do this they'll do the middle one. So, this is another intake valve these valves can actually go anywhere because they're not lapped anymore these are actually machined to a bit of an interference fit that as they hammer with the valves open and closing they actually bed themselves in. So, a bit of pre-assembly Lube on it. Seat it down. The next thing I need to put on is this which is a spring seat at the bottom of the spring and this is the type that goes at the top. You'll see there's different inner diameters different profiles that kind of thing. So, we'll pop that down then I'm going to put a new stem seal on. I'm just going to put a little bit of pre-assembly grease inside there too. You can see there on the stem seal there's a little spring little metal collar here and once that Clips over a lip here. That'll lock in quite tightly.

Now I'll get my spring and you'll see here the spring has tighter coils here and it's more open here and the tighter coils go down to the bottom. Then I've got this spring cap at the top pop that on now as we reuse the compression tool to get it so that the valve itself is poking out through the top of the spring. When I'm putting the spring compressor on to I'm making sure that the other end just by feel is centered on the face of the valve. That way you know it's pushing straight down. In here now you can see the top of the valve stem protruding a bit further than the spring.

You can also see if I rock this tool around I can move the spring a bit and that's kind of important. Because I've now got to put these little locking collets in, little keepers, and I need them both to sit in and sometimes you do need to maneuver the spring a little bit to get them to sit well. These are the two little collets or keepers and they're really easy to lose. So, keep an eye on them because if you lose one you know you can't get the motor back together until you order another one.

So, I'm just going to drop them in. They go small side down so they're tapered there's a large side and a small side. You have to get them seated like that so you can see they're sitting quite nicely inside there. Hopefully you can anyway and then all I have to do is back the spring compressor off and that will keep the whole lot together. We're done that's the basic procedure. As you can see it's not rocket science. You do just have to get those little collets seated as well. If they're all a bit wonky they're not going to sort of self-aligned as the spring releases. So, they've got to be nicely that way you can be assured as you take the spring off it's all fun.

Finally, a bit of a shocker PPE but do recommend glasses for these because they can go flying because there is a bit of pressure on the spring and you are there looking straight at it. So, the chances of going in your eye is pretty high. So, be careful with safety glasses that kind of thing. Now it's a case of just repeating a procedure so won't bore you with that. I'll go pop gala 3 in and then we'll start putting the camshaft in. In case you're wondering this section here are the valve guides. They're the ones that sort of align the bowels and they can wear out with the motion as well. So, sometimes you need valve guides replaced as well. So, here we've got all our valves and springs in. On the other side you can see each cylinders now got its intake and its exhaust valve in and they're all closed.

The reason they're all closed is that these Springs push the end of the valve up and pull the valve against the cylinder block. It's the camshaft that opens them so their natural position is closed and it's not until the camshaft exerts force on them down that they open. This camshaft has two obvious ends. The top here is threaded where we start getting our sort of driving pulley for the timing belt going on. The other end has this sort of groove in it and that's because the oil pump is driven off the bottom of the camshaft and that's where the oil pump gets its motion from. On the side here is where the fuel pump goes we have the oil pump on the bottom and the fuel pump on the side here. This fuel pump here is driven by a push rod here which is in turn driven by the camshaft. You can't get this in once the camshafts in so that's the next thing they put in. Once again put a bit of pre assembly lube on it and then pushes in from the back here. What I'm going to do now is put some pre-assembly grease where the camshaft rides. Then all we have to do is just drop it on.

This disk here or this lobe on the end of the camshaft is the one that drives that push rods you can see as you rotate it pushes out and then on the pump itself. That then pushes on the pump here and the pump spring-loaded so that's what returns the pin back out. So, the camshaft pushes it in the spring inside the pump pushes it back out. What I want to do is find a position where none of the lobes are pointing upwards. Get them all pointing to the sides and that'll make it easier when I drop the rockers on. Next thing we need to do is drop the rockers on but before I do that you'll see these are adjustable. For your valve clearances and I'm going to back them all the way off. I'll put some pre-assembly grease on the running surfaces in here as well. Also when you're dropping the rocker assembly on make sure that they haven't come round like this. You need them all to be flat so that it ends up tucking under.

This is the section here that runs on the camshaft and these push on the valves. They obviously need adjusting when it's back in position but for now we'll leave them loose. This rocker assembly has these dowels so we know it fits in a very specific location. Getting this all lined up can be a bit fiddly. These are sprung loaded to keep them in position. Give them a little play. Next I'm just going to put a little bit of oil on each of these rocker assembly bolts. Unfortunately, one of these rocker assembly bolts is missing for whatever reason. I'll have to check if it's in the packaging it came back from the engineer or whatever.

But these were there need to be talked up spec which I'd have to look up anyway. At the top here there's a camshaft seal so I'm going to pop that in and just put a little bit of pre assembly Lube on the inside of it here. It's nice and easy to get that in now because I haven't torqued the bolts here down so there's a bit of gap and then it'll clamp down on the seal once I do that. I had to keep working on this a little bit when the workshop was too noisy to film unfortunately. But I've got the rocker assembly bolted down now. I ended up getting a bolt to replace the missing one from an engineering shop down the road. It's right diameter and the right thread and there's a high tensile bolt. And it's a lot faster than trying to order a Honda part. I've also now just got the fuel pump on the oil pump back on and I've thrown the cam pulley on. Which I think in Honda speak they call it the pulsar pulley or something like that. Now I need to be able to rotate the camshaft. Before I do that though I'm just going using oil can to put a fair bit of oil on the camshaft itself. You could probably oil it first but I'm doing it now and that way the rocker arms don't run dry against the camshaft as I rotate it.

Before I put this cylinder head back on the engine block. I need to rotate it so that cylinder one is at top dead center. This is reasonably easy on this motor because we've got the timing mark on the pulley and it's also there marked on the block where after lighted up. The other thing to know is that Honda's turn counterclockwise well this particular one does anyway. Which is not quite as common as motors turning clockwise. You'll see here there's a tee and an arrow this is cylinder one, then we got cylinder two, and cylinder three. On the cylinder block down here you can see that this is the mark that we line it up with.

So, as long as the T in this arrow is lined up with T in this arrow we know that this is rotated so that cylinder one is on top dead center. If we flip it over now we can see we've got an exhaust port open on cylinder number three the intake port open on cylinder number two and both valves closed on cylinder number one. So, cylinder number one is top dead center of its compression stroke. Previously there was also a couple of dowels in this cylinder head. I've taken those out and put them onto the engine block because I want to be able to then hang the head gasket on the engine block and then put the silver head on.

To remove these dowels you put one of the head bolts through the down and then it allows you to sort of grip the dowel with some vice grips and wrangle it and get it out without crushing it. Speaking of tips, another tip Aaron gave me while we were talking about putting this together. He's saying that when I do the valve clearances to actually make them slightly larger than specification. The reason for that is that because these aren't lapped they are just cut to an interference fit. As they sort of hammer in they will actually go into the head a little bit further. Which means the gap will close up. So, by starting you know what a tooth out of a larger gap then you'll get closer to the true spec. Then get it hot, run it, let it cool down, check them again.

These are the two dowels I was talking about before and here's our new head gasket. With a coating of Haarlem are on both sides and I gave this surface here below quite a good cleanup with a wire brush and actually just turned each piston to top dead center so I could give it a bit of a cleaning as well. On this side you can see this is where the exhaust from the headed actual sort of exhaust manifolds part of the head and it heads down here. This side is where our carbs and everything will come on and you can take manifold will join to the head there.

And we've got a new gasket for that too. Well that wraps it up for today. Sorry I didn't get to film every step of the process completely. But it gets really hard once the workshop gets busy and it's noisy and it really doesn't work. Alright getting back to the job we just did I do have that video on adjusting the valve clearances.

So, I put a link to that and I'll also be doing the timing belt on the green machine. And that's actually a neat sort of follow on from this video because it shows how to then get the cam and the crank perfectly in sync. In that video I'll also show how to look at the cam lobes and determine whether cylinder one's at top dead center on the compression stroke. If you don't have timing marks on the cam pulley. In the meantime though we'll pick up the boat building project and next time you see that we'll be putting the bulkheads up on the strong back. All right well take care and I'll catch you soon. See ya!