Exhaust pipe gasket

[Edwin Howard]

I’ve ran into a slight problem. While more of an inconvenience, my Neptune wc1’s exhaust pipe has no sort of gasket or seal between the exhaust pipe and powerhead. This, paired with the loose fit between the pipe and powerhead causes the excess oil in the exhaust to spew down the pipe and create a sticky mess. I’ve tried to fit gasket material in the gap, and that is too thick, and I don’t like the idea of putting Napa’s Make-a-gasket there either. Does anyone know of a way to seal the gap between the pipe and powerhead and prevent oil from getting everywhere on the motor?

[Sam M.]

I haven’t worked on that model of motor before so don’t know how it’s connected.  A picture would be helpful.  Assuming it’s just two surfaces bolted together, here are some thoughts:

Let’s start with the simplest things first.  Are you trying to slide the gasket paper into the gap of the assembled pieces, or assembling the pieces with the gasket paper squashed in between?  Be sure you’re doing the latter.  It should make a difference because of gasket paper compressing.

Are the surfaces scraped up?  Might need liquid gasket maker if so, or something else to smoothen the surface(s).

Is it all torqued properly?

There are different thicknesses of gasket paper.  Maybe look for some thinner stuff??

Some people have had success getting a paper-based product like a cereal box, making a gasket out of that, and giving it a light grease coating before using it without problems. A liquid gasket sealer might have been added to that though.  This would let you experiment with different material thicknesses without buying whole rolls of gasket material.  For something thinner, maybe try it with a paper bag??   Without the liquid gasket, that might be a cheaper alternative than a whole roll of ultra thin gasket paper you’ll only use on this one gasket.  Having some random paper at the exhaust might be a fire hazard though.  Hmmm.

How about aluminum foil?  It isn’t thick and shouldn’t catch on fire.  Not sure if it would seal well, though it could fill the space.

[Edwin Howard]

I got pictures of how the pipe is held in. The simplest way I can describe it is that it is sandwiched between the lower unit and the powerhead. It does look clean in the pictures because I cleaned it and haven’t ran it since.

I haven’t really tried to make a gasket yet, because I wanted to know what any possible solutions were. There really is nothing to torque down, and the machine screw at the very end of the pipe where it meets the lower unit is to keep the pipe from rotating with vibration. Hopefully the pictures help, and if I need, I can always take more.

[Edwin Howard]

Here is the picture of how the pipe fits into the powerhead.

[Sam M.]

Hmm, so that’s a different situation than what I wrote about earlier.  Looks like a tiny little bit of pitting on that exhaust tube.  It looks pretty tight clearence-wise at the top between the tube and powerhead so maybe just add thin little layer of heat-resistant (and fuel-resistant) paint on the tube around the top section where to powerhead blocks it from being seen, and wipe the paint smooth before it dries so it doesn’t magnify the roughness of the tube.  This would hopefully smooth out the tube’s surface so the extra fuel wouldn’t escape by seeping down through the low parts of the slightly uneven pitted surface on the tube.

However, you mentioned a loose fit.  I’d be more inclined to suspect that is the problem and not the fuel leaking down through the minor pitting.  If the tube wiggles vertically, maybe a gasket somewhere else can be swapped for a thinner one to compensate for the gap and reduce the vertical clearance.   If it wiggles sideways, maybe try the paint to widen the tube just a bit.  Looks like a teeny tiny bit of material wore away somehow, circled in the attached image, but I don’t think that would be enough to cause the problem…

I haven’t tried any of this.  Just randomly brainstorming in hopes that something might help.  Good luck!

[joecb]

It may be impossible to completely stop leakage from that slip fit joint. But let’s try minimizing leakage… If the tube is corroded where it fits up into the aluminum housing, it needs to be cleaned up. If you have the capability to expand the tube for a tighter fit, this can be done by carefully hammering the surface of the tube while rotating on a steel bar. Proceed slowly , trying the fit and maintain roundness.

Other than that fix… consider using high temperature silicone sealer. Also … at the auto parts store they sell “muffler sealant” , kind of a grey paste the comes in a squeeze tube. Or, try the suggester aluminum foil, different thicknesses, foil, HD foil and finally pie plate.

Joe B

[Edwin Howard]

Thanks for the suggestions! The motor previously blew a head gasket and while I had it apart, I noticed major signs of saltwater use. That, paired with the heat of the exhaust is what I suspect to have caused the pitting. It does not go deep into the pipe and it doesn’t seem to be corroded at the spot where it meets the aluminum, so I am not too worried about that at the moment, but I’ll still clean it up. I figured that it wasn’t uncommon to have large amounts of exhaust deposits left behind on the pipe and seeping through cracks, but I will still try a bit of silicone or a tin-foil gasket.

[Gary Haight]

I think I know exactly what you are experiencing. The exhaust and excess oil does go down the inside of the exhaust tube BUT some does leak out around the outside of the exhaust pipe where the pipe fits into the lower engine flange. My exhaust pipe is polished brass and when this happens, it really doesn’t look good and makes a mess. This it what I did and it works to stop the exterior leak.
1-  I unbolted the power head to remove the exhaust pipe.
2- clean pipe and inside of flange thoroughly to remove oil and grease buildup.
3- I used Permatex ultra copper high heat silicone and put a SMALL bead (think of how small the area is where the oil is coming out and don’t overdo the silicone) of silicone inside exhaust housing half way up in the housing.  Slip pipe in, spinning back and forth a little to coat pipe while inserting into flange.
4- put power head back on aligning everything up and let silicone cure 2 days.

 

 

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