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You may or may not be amazed at how similar the service procedures are between multiple different four-stroke engine brands
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Believe it or not, they are all basically the same and we're going to show you how
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Just like the two-stroke service items, a four-stroke engine requires all the same service items no matter what brand it is
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They all require oil, an oil filter, spark plugs, thermostats, engine fuel filters
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boat water fuel separators, most will have a belt, anodes, grease points, water pump impellers, and gear loop
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We're going to do a service on a Yamaha F-115 4-stroke as well as a Mercury 115 forestroke just to compare the procedures
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The first thing we want to do is pull the dipstick, clean it off, and reinstall it to check the oil level
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Like on this Merck, there wasn't even any oil on the dipstick, and then on the Yamaha, the oil level was a little high
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If you don't see any oil on the dipstick, it might be a good idea to go ahead and do a compression check on the engine just to be sure there's nothing wrong
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And last week's video was all about compression tests, so we won't cover that here today
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We'll go ahead and drain the oil out of the engine now after check
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checking it. And all outboards have an oil drain plug somewhere on the engine. Like on these
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mid-sized 115's on the Merck, it's here on the port side of the mid-section, then on the
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Yamaha, it's here on the back of the engine. You can use a piece of the oil filter box as a way to funnel the oil on the Merck, or like on
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Yamaha, a piece of build hose works great to drain out the oil into a bucket
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While that's draining, we can go ahead and change out the oil filters that will be mounted
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somewhere on the powerhead You got to be careful with these filters though that are on the side like this because they generally make a mess when you take them off Then we can clean the surface where the filter goes and install the new filter with a little bit of oil or grease on the seal to make it easier to get off next time
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You'll also notice that on a four stroke once we get the ignition coils or coil leaves off the spark plugs and get the plugs pulled out of the engine
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They can develop this burn mark around the bottom of the ceramic on the plug here
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Once this gets to this really burnt looking base and the tips also lurk burn up, it's
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time to change out the plugs. When installing the new plugs, put a little bit of ANICs or something on them just to help
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on pulling them out next time. But just a little bit, you don't want to go overboard with it, just a little bit goes a long way
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Next up we'll change out the thermostat, which as you can see, this is a perfect
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example of why you want to at least check the thermostats every other year. It doesn't
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take much for them to stick and then once they get stuck like this, they can begin to build
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up salt and start to eat out parts of the housing where the thermostat sits. Not to mention
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that this thermostat was stuck open anyway. Though many of you probably live in freshwater
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areas where you don't even have to deal with anything like this, so this is irrelevant to you
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But after installing the new thermostat, we'll move on to changing out the engine-mounted fuel filters
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Some engines, like our Yamaha, will have a cup that you can unscrew and then it will have the fuel filter inside the cup
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You might notice how brown and discolored this filter is, that's a good sign that it's time to change out the filter
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Then on the Merck, it actually has two fuel filters on the engine
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The trick to these is also just like the trick to getting the canister filter off of the HPDI that we showed you a couple weeks ago in the two video You just have to push in on the filter then depress the red tab here on the hose and then
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we can pull the hose off of the filter and dispose of the filter. When installing the new filter, just make sure that the arrows are pointing towards the fuel
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injectors as well. Now the grease points on the four-stroke are basically the same as the two-strokes
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There are the points on the bracket here, and then one on the midsection, and then one on the mid-section
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And depending on the brand or model, you might find some grease fittings on the handles
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Just a couple of pumps of grease will do fine and we can move on to changing out the boat water separators
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Which if they look as rusty as this, you might want to think about setting a reminder to change it out a little more often
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When it comes to the water separators, you can see why they are so valuable whenever you take it and dump it out into a clear jar and you can see all the debris that gets collected in them
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Then just like the two strokes, we want to top off the power tilt and trim reservoirs
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And then we'll want to check the anodes on the brackets and change them out if they need to be changed
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Also, don't be shy with the grease whenever you put the anode bolts back in as well
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Now the only thing left to do is pull the lower units and service them
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You want to pull the prop off first and then there will be bolts on the sides of the lower
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unit as well as a bolt up under the trim fin anode here
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We do have videos on completely resealing the lower units. We do have videos on completely resealing the lower units, but a couple of main tips to look
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at whenever you do a service on a lower unit, like on these Yamahs, this top seal cover that
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goes above the drive shaft carrier seals, if you can pull the rubber off the metal like this
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then it's time to replace it. Then if you see the springs on the seals broken or rusty like this, then we've got to pull
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the carrier and replace these seals Which isn hard to do with a couple of big flathead screwdrivers you can pry up evenly on both sides of the carrier and get it to come up
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But be careful not to lose the shims or the bearing race that are underneath the carrier
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Now just stick the carrier in a vise and pry out the old seals. Clean up the carrier and press in the new seals with a socket
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And we can grease up the O-ring and reinstall the carrier with the new seals
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Now just grease everything up as you reinstall the water pump impeller and the water pump housing assembly
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With fresh gear loop in the lower unit and everything service, we can grease up the lower unit and reinstall it onto the engine with the gear case in neutral
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Make sure to line up the shift shaft and slide it back up into the midsection
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We'll reinstall all of the bolts and the prop and now give you a sneak peek into next week's video
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where we are taking out a 35-foot motion and breaking 100 miles per hour on the water
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So don't forget to subscribe to the channel because you don't want to miss that
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Thanks for hanging out with us this week, and we look forward to seeing you next week
