Spaghetti seal

[byacey]

Where the spaghetti seal meets the prop shaft seal carrier on my big twin- is the spaghetti seal rubber supposed to overlap and be crushed tight against the O ring on the seal carrier? I am concerned I might have a slight leak here; I trimmed the seal flush with the end of the aluminum housing. What is the recommended installation method?

 

[muskrat]

Re: Spaghetti seal

you trimmed it properly,ctting it off at end of housing,now just glue to in with a adhesive..

 

[DHPMARINE]

Re: Spaghetti seal

Bill,<br />Sounds like you did the seal right.If you don't use sealer on the bolts that hold the parts together,they will leak.A pressure test in a tub of water should help you pin it down.Also some people don't realize the outside shell of the seals need sealer,as well.<br /><br />DHP

 

[OBJ]

Re: Spaghetti seal

If I remember right, don't the OEM manual say to leave a bit sitck out beyound the slot...say like a 32nd? This little bit is supposed to lay against the head and seal assembly supposidly to help seal it better. Do agree though that generous use of a sealing compound on the orings, bolts and mating surfaces is a must.

 

[Goldfish]

Re: Spaghetti seal

I too have a big twin that I rebuild the lower unit. What sort of sealent should I use to seal up the spaghetti seal? Perferably from an auto parts store

 

[Paul Moir]

Re: Spaghetti seal

If you're going to the auto parts store, "Permatex Aviation Form-A-Gasket 3-H" sealant works well. Marpox/Boat Armor 1000 Sealer is the proper stuff, but getting hard to get sometimes. RTV silicones can be attacked by the EP additives in hypoid gear oil so you don't ever want to use anything like that (Permatex black/blue/orange/etc).<br /><br />If you didn't get it the first two times, slather all the mating surfaces and bolts in sealer. The 3-H stuff cleans up with rubbing alcohol.

 

[byacey]

Re: Spaghetti seal

I used the brown Permatex aviation gasket cement. It looks like there might be a little oil seepage where the spaghetti seal meets the O ring on the prop shaft seal carrier. I might have to re-do the spaghetti seal and leave it slightly longer and allow the o ring to crush against it. I haven't opened it yet. Are you suggesting to use the permatex to fill whatever little void is there instead of re-doing the spaghetti seal?

 

[OBJ]

Re: Spaghetti seal

A good idea is to run the compound around the oring slot, put the oring in and run compound over the oring. Don't forget the oring on the propshaft head, coat that to.<br /><br />If you think you have a leak, put some air pressure to it while submerged in water. That will tell you right away.<br /><br />And do listen to Paul on NOT using any silicon based stuff.....so many times I've found that stuff used on lower units and it comes out looking like snot.....just don't work.

 

[lark2004]

Re: Spaghetti seal

the manual says to leave a bit sticking out, I'll check how much as soon as I get home.

 

[lark2004]

Re: Spaghetti seal

1/32" sticking out. both sides.

 

[byacey]

Re: Spaghetti seal

Thanks guys, I'll have to make a fitting to pressure test it and see what I have.

 

[Paul Moir]

Re: Spaghetti seal

Let the sealant dry a good long time before you assemble. It's really the sealant that keeps those cases sealed (IMO) not that bit of spagetti. It's not even run inboard of the screws afterall. Don't bother testing with more than +/-5psi.

 

[TimMattson]

Re: Spaghetti seal

Bill,<br /> We use the Type M OMC on the Spaghetti seal but I thought the RTV black was dabbed on the ends at the rear seal.....Ill verify.<br /> Pressure tests dont always reveal a leak at higher rpms.....A cheap bicycle pump with gauge and hose may work after swapping the fitting from a lower unit lube fill assy.Soapy water will reveal hidden leaks if not obvious. <br /> I sent you head gaskets pics(finally .....)did you get them or?<br /> TM

 

[byacey]

Re: Spaghetti seal

Hi Tim, yep I got the picture, I just have to verify that's the one my 45HP uses. I'll be in touch soon.

 

[byacey]

Re: Spaghetti seal

So, I pulled the gearbox apart tonight, and it appears it was leaking where the lower gearbox cover meets the prop shaft seal carrier. I couldn't see any reason why it didn't seal other than perhaps I was to quick to put oil in before the aviation cement was dry. I'll leave it for a week or so now before I pressure test and re-fill. Paul, do you let the gasket cement set up and dry before you re-assemble? I am using permatex #3D.

 

[Paul Moir]

Re: Spaghetti seal

It never really dries hard but it goes from surupy to tacky as the solvent evaporates. Let it go nice and tacky before assembling (a good 10 to 15 minutes. I set the parts on top of the furnace), then let it sit a while before pressure testing.<br />I've done it too early. Nothing so disheartening as seeing your sealant oozing out of the seam because you were in too much of a hurry.

 

[OBJ]

Re: Spaghetti seal

If I could add a little here....check the mating surfaces for any burrs that could keep the halves from mating up flat. A fine file will take care of them.

 

[Wizard1]

Re: Spaghetti seal

I'm about to replace the seals in the gearcase myself. I was wondering which way I should install the spaghetti seal? I noticed that there are 2 ways to do it (trim flush with the case or leave a 32nd hanging out). Also, the gearcase o-ring, does it go onto the gearhead assmbelly or up against it between the shaft seal and the gearhead assmbelly? i ask this due to the fact I have never attemted this and all I have seen so far is a diagram of the gearcase. One more Q, I bought some 1104 liquid gasket and was wondering exactl how and where to apply it?<br /> Thanks

 

[Paul Moir]

Re: Spaghetti seal

Go with the factory method, leave 1/32" hanging out. It workes and doesn't use RTV silicone, etc.<br /><br />The o-ring goes into the groove on the gearhead assy on your 18hp. Have a look here:<br /> http://photobucket.com/albums/y18/geekomatic/?action=view&current=P6081250.jpg <br />Be careful to get the forward bearing pinned in place before torquing down the cover.<br /><br />1104 sealer? You mean Three bond 1104 (aka, Yamabond, aka (I'm pretty sure) permatex motoseal grey)? That stuff you just brush on (foam q-tip, etc) and assemble immediately. The idea is to get the excess to squeeze out before it sets up completely. I always clean the surfaces with acetone first when using it. I haven't tried it on a Big Twin gearcase, but it seems to stand up to l/u lube fine in other applications I've tried. Works great for a Big Twin crankcase sealant too. You want to let it set assembled for a good long while though.

 

[byacey]

Re: Spaghetti seal

So far I have re-done the spaghetti seal and oring 4 times, and when pressure testing I still get a slight leak where the spaghetti seal meets the prop shaft seal carrier. When pressurised to 5 psi it slowly leaks down to about 1 psi after 3 hours or so. I am considering some other kind of sealant rather than Permatex, it doesn't seem to fill any small voids, like around the end of the spaghetti seal.