81 Evinrude 25 HP - No fuel to bottom cylinder

[cchildr84]

When I removed the cylinder head I noticed that the bottom cylinder was dry compared to the top cylinder, so that led me to wonder what might cause the bottom cylinder not to get fuel. I read to forums, and read some posts that said it my be a stuck reed valve. So, I got to the read valve and checked it out. Not knowing much about them, I would say that were in good shape, none of them were stuck, and looked to be in pretty good condition. I assume the stop leafs are supposed to be curved, see photos below. Also, in the bottom cylinder the was a little surface rust, not bad, it wiped away with a rag and carb cleaner. Any idea where the water would get in.You can see on the reed valve that feeds the bottom cylinder there is a little rust as well. FYI I am in the process of replacing the head gasket and exhuast manifold gaskets. Your advise is greatly appeciated.

 

[willy007]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

How did your head gasket look when you removed it? If that was blown than odds are that that's where your water came from. As far as the fuel issue... did you check your carbs out at all? You may have a blocked jet resulting in no fuel getting into the cylinder which is bad news considering that that's how the rings are lubricated. Since everything's torn apart, rebuilding the carb probably wouldn't be a bad idea.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Well, I have the carb off and have a rebuild kit on order. Not really sure what to look for, but I haven't broken it down yet. I will be ordering a service manual to get through the rebuild. This will be the first time i've done something like this. Is all that hard, I watched some videos on you tube and it made it look easy. So we'll see. As for the head gasket, when I removed it, it tore apart at the top right, but again never really doing this stuff before, i'm not sure what a bad one would look like. The compression, was 90 top and 83 bottom when I did my test. Hoping the new gasket will improve those numbers as well.

 

[RogersJetboat454]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Well, I have the carb off and have a rebuild kit on order. Not really sure what to look for, but I haven't broken it down yet. I will be ordering a service manual to get through the rebuild. This will be the first time i've done something like this. Is all that hard, I watched some videos on you tube and it made it look easy. So we'll see. As for the head gasket, when I removed it, it tore apart at the top right, but again never really doing this stuff before, i'm not sure what a bad one would look like. The compression, was 90 top and 83 bottom when I did my test. Hoping the new gasket will improve those numbers as well.

Not that hard at all to rebuild a carb. As for the service manual, I don't know if it's what your ordering, but the factory manual is the BEST to get. The aftermarket manuals (Clymer, and Seloc) cover too many engines to give detailed information, and are often vague or WRONG with the info they give you.

Take a good look at the head gasket, particularly where it seals around the bottom cylinder. If you see any spots with pieces missing forming a little valley, that will allow water in from the water jacket, and compression out. You also want to dress the cylinder head (clean up the sealing surface so it's clean and true). You do this by getting your self a piece of plate glass, and some fine grit sand paper (300-600 grit should work). Tape the paper to the glass, and rub the sealing side of the head on the paper in a figure 8 pattern until the low spots are level with the rest of the head.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Do I do this same procedure for the block? As for the manual, the one I've found is available at outboardbooks.com. Not sure if it's a factory one or not. It looks lite it's manufactured by Ken Cook Company. It states that the SM is for 20, 25, 25COMM, and 35 HP motors. Does this sound on par with a factory manual? If not, can you direct me somewhere where I can find a factory one? Thanks.

 

[AlTn]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

sounds like what you are looking for...you may find some on ebay as well

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Yeah, all I've been able to find on ebay are parts manuals for 81, no service manuals.

 

[RogersJetboat454]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Do I do this same procedure for the block? As for the manual, the one I've found is available at outboardbooks.com. Not sure if it's a factory one or not. It looks lite it's manufactured by Ken Cook Company. It states that the SM is for 20, 25, 25COMM, and 35 HP motors. Does this sound on par with a factory manual? If not, can you direct me somewhere where I can find a factory one? Thanks.

No, you don't necessarily need to dress the block. Just clean it up best you can, and keep as much junk out of the cylinders as you can.

Ken Cook is the authorized reprinter of the factory manuals for vintage OMC outboards.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Sounds good. Now I've just got to wait for all of my parts to come in.

 

[boobie]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Be sure to do the exhaust cover gaskets. Number two piston looks like it had water in it.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Yep, that's on my parts list of items that have been ordered, pretty much I'm replacing every gasket on this thing. That's what i read elsewhere, so the exhuast cover gaskets are a possible culprit for getting water into the cylinder? I've also got the gasket for the powerhead to exhuast housing, but I'm not sure if I want to attempt replacing it, as that would involve removing the entire powerhead. Like I say, I'm going to order the service manual, but is it pretty easy to remove the powerhead in order to replace that gasket?

 

[jasper60103]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Yep, that's on my parts list of items that have been ordered, pretty much I'm replacing every gasket on this thing. That's what i read elsewhere, so the exhuast cover gaskets are a possible culprit for getting water into the cylinder? I've also got the gasket for the powerhead to exhuast housing, but I'm not sure if I want to attempt replacing it, as that would involve removing the entire powerhead. Like I say, I'm going to order the service manual, but is it pretty easy to remove the powerhead in order to replace that gasket?

$16.99 and free shipping...
1979 Evinrude Service Shop Repair Manual 25 35 HP Models Boat Excellent | eBay

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Well, as I got to feeling around deeper into the cylinder last night, in cylinder #2 (bottom) I felt some scoring. Looking at it, there is kind of a white residue, which I'm thinking is plastic from the overflow nipple. Reason I say this, is because when I bought the motor (used) the original overflow nipple wasn't even connected to the exhaust housing. At some point the plastic threads had melted, and so I'm guessing that the material that melted somehow got through the exhaust housing and into the ports. Hopefully this can either be honed away or bored enough to eliminate the scoring. My only oversize options are 0.020 or 0.030. What do you guys think?

 

[RogersJetboat454]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Well, as I got to feeling around deeper into the cylinder last night, in cylinder #2 (bottom) I felt some scoring. Looking at it, there is kind of a white residue, which I'm thinking is plastic from the overflow nipple. Reason I say this, is because when I bought the motor (used) the original overflow nipple wasn't even connected to the exhaust housing. At some point the plastic threads had melted, and so I'm guessing that the material that melted somehow got through the exhaust housing and into the ports. Hopefully this can either be honed away or bored enough to eliminate the scoring. My only oversize options are 0.020 or 0.030. What do you guys think?

Post a close picture of what you're looking at.
Does the white residue actually feel like plastic? Can you easily scrape it away with a thumb nail?
Is it actually white, or a silvery color (aluminum residue from a scuffed piston).

Have you pulled the transfer port covers off to get a look at the sides of the pistons, and condition of the rings?

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

I'll try to get a picture taken at lunch. All I have off so far is the head. I plan on breaking it down further to get to the rings and pistons, but I thought it my be better to wait until I have the manual. I see if I can scrape anything off, it's gonna be tough though because I have no nails, haha.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

See photo below. The area I'm referring to is at the top left, the uppermost port hole. It didn't scatch off with my nail. While I was at it I went ahead and started to remove the bolts from the exhuast cover; breaking (2) SMH, I noticed that on most of them there was a white chalky substance, looked liked battery acid on a dirty battery terminal. Any thoughts on what that could be and back to the first question from today, does the scoring look like its shallow enough to be either hone away or bored away?

 

[RogersJetboat454]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

From my chair here, looks like some aluminum from the piston.

May be able to hone it out, and install a new STD size piston and ring, all depends on how bad it is in person.

That white chalky substance is aluminum oxide (A.K.A. white rust). Yes, aluminum does rust, just not in the same manner you see with steel and iron. The oxide is usually heaviest around areas of dissimilar metallurgy (like the steel bolts you're removing). A little heat from a propane torch (not MAPP) may aid in easing them out with out breaking them.

See if you can also get the transfer port covers off (opposite side of the block from the exhaust chest). Once they are off, you will see the intake ports, and will be able to see more of the pistons and rings by looking at their sides through the ports. Take pictures when you do.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Will do. Once the exhaust cover is off, what can be used to clean away the oxidation?

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Ok, I got the intake cover off last night. As suspected the top cylinder looked to be in pretty good shape, but the bottom was in rough shape. The bottom cylinder deffinately has some issues, but as bad as it looks, to the touch I can not feel any abrations on the piston. Obviously it is going to need to be replaced. However, the big question is what caused this, is it due to the fact that the bottom cylinder didn't appear to be getting any fuel, and if so, what would cause the bottom cylinder not to get fuel. I feel as though I've ruled out any reed valve issues. So I assume that leaves either fuel pump or carburator problems. I have a carb rebuild kit on order. What do you guys think. What can I do to ensure this doesn't happen again once it's rebuilt. Also, you'll notice there is a bunch of red residue. To the touch it feels rubbery, as though it's some kind of coating, any thoughts on what that is and if it should be there? Thanks.

The first to pictures are of the lower cylinder, the next two of the upper.

 

[cchildr84]

Re: 81 Evinrude 25 HP - No fuel to bottom cylinder

Ok, I got the intake cover off last night. As suspected the top cylinder looked to be in pretty good shape, but the bottom was in rough shape. The bottom cylinder deffinately has some issues, but as bad as it looks, to the touch I can not feel any abrations on the piston. Obviously it is going to need to be replaced. However, the big question is what caused this, is it due to the fact that the bottom cylinder didn't appear to be getting any fuel, and if so, what would cause the bottom cylinder not to get fuel. I feel as though I've ruled out any reed valve issues. So I assume that leaves either fuel pump or carburator problems. I have a carb rebuild kit on order. What do you guys think. What can I do to ensure this doesn't happen again once it's rebuilt. Also, you'll notice there is a bunch of red residue. To the touch it feels rubbery, as though it's some kind of coating, any thoughts on what that is and if it should be there? Thanks.

Does anyone have any thoughts?