Replacing the Rear Main Seal on a Sailboat (Perkins 4.108 Diesel)

Thanks Good morning, I'm on my way to Maine because the engine on my friend's

sailboat

needs some work. It's a Perkins 4.108

diesel

engine and it has a couple of issues, number one, the

rear

main

seal

, has a significant leak and number two, one of the exhaust manifold bolts broke off almost flush with the cylinder head, so it is necessary to extract them. If you've never seen the engine compartment on a

sailboat

, they are extremely tight, generally speaking, this one is no exception, so what we're going to do is take the engine out and I'm actually going to take it home so I can work on it in my workshop.

That's why I drive my truck well. I arrived at the Boatyard and it will be one of these boats. Around here somewhere, I'm pretty sure she's 36 feet long and all wrapped up for the winter. Look inside, it's quite nice and there's the engine. Look how hard it is to get out. This is the crane we are going to use. to get the engine out, well foreigner, back here, okay, that's good, we ended up having to pause for a moment to remove one of the engine mounts. The engine mount is fine, a little more. I think she's out of the hole.

Well, still. yeah yeah we're good look at that keep it there if you're a baby now okay we've got it in place warning don't even think about using starting fluid good idea so I took the engine home now this is. a completely original engine from 1985 with about 3600 hours and my concern here is that if this engine has excessive exhaust, what could actually be causing the oil leaks is when the combustion gases escape past the oil rings. piston towards Therefore, the crankcase pressurizes the crankcase, which can force oil out of cracks and various

seal

s in places that cause leaks.

I'm going to try to test the leak by running this motor, so I have it connected to a battery. and I have a makeshift fuel tank. This water pump is not supposed to run dry, so I'm just going to throw a garden hose in the bottom and that should lubricate it if there is excessive leakage. I hope to see it work. it comes from here at the oil filler cap in the form of excess pressure and maybe even smoke at worst, well I didn't really see if there was any leak but I'm going to grab a piece of paper to check for sure .

If there was certainly any, it wasn't bad because this lid didn't come off on its own, but as I put my hand there it was hard to tell if I was sucking air in or if air was coming out, all I could tell was that there was air moving there so strange, so that piece of paper was being sucked against the oil fill here by vacuum and that tells me that this engine is in very clean health, the piston rings are in good condition and should have adequate compression. You should be able to go ahead and replace the

rear

main

seal and hope it doesn't happen again if there was a significant knock.

The answer would be to rebuild this engine. Next thing I need to do is remove the injection pump to send it to a specialist for a rebuild, before I can get to the rear main seal I have to remove the transmission, yes it definitely looks like we have a leaking rear main seal follow the oil that came out and then it is covered with strange oil, yes. I can tell you right now that whoever installed these rear main seals last did a very poor job and that's probably why it's leaking, so this is the top half of the rear main seal and here's the old rope type seal and Honestly, It looks like it was installed by an ape, so the seal ends here and here are supposed to be flush with the housing and here they are quite recessed.

In fact, I can use my calipers to get a rough idea of ​​how much and that's about 30 mils. Now I'll show you the proper way to install this later, but essentially you press it into place and then cut the ends to the proper size, leaving it sticking out 15 mils on both sides, when you install the two halves together, it compresses it and it's over. flush. It would have left such a gap that the oil definitely could have leaked out quite easily before reinstalling the seal. I spoke to the owner about the oil pan gasket here, which appears to be leaking, although I'm not 100 sure because I think the injection pump gasket was leaking and could have leaked and then spread to the back of the engine that way anyway.

I think the safest thing to do here is remove the oil pan and replace the gasket because it's pretty easy to do at this point and, especially considering how poorly the rear main seal was installed, the same people also replaced the gasket of the oil pan and I think there are a lot of other things, so they may have done a bad job. The foreigner has quite a few leaks that need to be fixed. I think the injection pump gasket was leaking, the oil pan gasket is leaking and then here on this side. we have this gasket that was leaking and then this thing here was leaking, but I tightened it with my hand, so I hope that resolves itself.

Oh, this is what it looks like inside the crankcase. We have a very strange looking crankshaft. For this surface I went and scraped it with a razor blade, I cleaned it really well with acetone so the new gasket would stick and the oil pan is actually aluminum so be very careful when scraping this surface with a blade razor is fine for these joints. I'm thinking just a very thin coat of RTV over this will help seal this cork gasket going over here with a thin coat of weird r2v. Then I thought about

replacing

the gasket with the oil. filter housing yes, it looks like this was leaking from the bottom.

I think thanks to the foreign Tex high tech gasket sealant, especially when it comes to cork and paper gaskets, the front timing cover also seems to be a source of leaks. I'm a little sorry. It's silly because I didn't even need this extractor for this. You can see this has been dripping from down here. The old front main seal was removed. The new seal is coated on the outside, so you don't need to use any sealant. The three-quarter bushing should press this evenly, okay, great, that looks good to me, so I have this cork gasket here and it leaked right here before and what it looks like is like a piece of aluminum foil sandwiched between two pieces of cork and I think this might leak again because it's a low quality gasket, so I think we'll get better results if I just use RTV on this.

It's very important to center this seal in relation to the crankshaft pulley, so I'm going to go ahead and put this on and that should allow me to center the seal, slide it in very smoothly, okay, that's pretty good, these bolts are just barely tight with the hand. I'm going to let this dry for a moment, we'll come back. Come back and tighten it later okay the next thing I want to address is this broken exhaust bolt so there are two ways to remove a broken stud or stud like this. The first is to drill a hole in it and then try using a puller to remove it.

Number two is my favorite way and that is to weld a nut on it and the advantage is that welding a nut heats up the bolt a lot which will break down any rust that may be there and then when it cools. It should be much looser. I'm going to start by trying to add material to this to strengthen it. I'm not really sure if I got good enough penetration there, but I guess I'll go ahead and try welding this nut and see what happens worst case, if it breaks then I'll do it again. This may not be pretty because this nut is zinc coated, so yeah, don't breathe this stuff, okay, try number one.

I don't think this is going to happen. it works, so let's see, yeah, no, I don't think so, I think so, then that will break right away, yeah, okay, this time I'll try a bigger knot, well, there it is, while I'm doing it, I decided that It would be a good option. The idea is to replace all the bolts now, this is what the traditional rear main seal looks like. Actually, it is like a rope type material. There is a kind of magic in the middle that is darker. I'm not sure what it's made of, but these engines actually are.

Known for leaking rear main seal due to this design, what we have chosen to do is use this new updated design which is a new type of rope type seal and should hopefully resolve the oil leaks. Well, the first step is to take this. rope and press it into this slot here making sure to leave some sticking out at each end, it actually seems to fit pretty well before you get to the ends here. I want to make sure the bottom is fully seated and I'm going to use a bushing. or something like this to roll it up if it's not fully seated you may see it seat itself later and shrink into place and leave gaps here that might have been what was done the last time this seal was installed, OK?

I need to cut these ends leaving 15 mils sticking out and that's so much, it's not much. I think it's easier to level it by cutting from this side, but I don't want to push it, so if I take a piece of wood and glue it to the back here. I can use it to hold it in place while I cut oh wow it cuts very easily oh that's nice beautiful look at that pull a little bit of assembly Lubricate this just to lubricate while the seal is breaking that's a lot more than I needed , but okay, so these steering wheel bolts are spaced unevenly so that the steering wheel only fits in one direction, which is important for balance.

Okay, so I have a dial indicator here set to the The steering wheel was set to zero and the maximum allowable deflection is 12 thousandths of an inch, so I'm going to crank the engine and we'll check that six thousandths, well, that was less than one rotation, it is definitely well below 12 thousandths. of inch, okay, I have the engine fully charged and here we are back at the Shipyard, all the engines in place. The plan is for me to go out and film this on launch day and see how it goes, hopefully it won't. No more leaks, on launch day, thank you.

The engine seems to be running well. Once on the water, we would cruise the Piscataqua River into the Atlantic Ocean on our way to the marina to reach the open ocean. We had to cross several bridges. With a mass height of 46 feet we had to request a drawbridge to be raised, there was a storm moving behind us and when we reached the open ocean we found rough conditions with large waves. Fortunately, as we entered the marina, the wave calmed down. It is the least organized outing in the world. We return to the marina. The engines run well.

We haven't detected any leaks and we didn't get rained on either, so everything is fine. Thanks for watching.