Slighly Bent Cylinder Face.... Sealant?!?

[brettagostini]

I have an 81 Evinrude 140 I'm rebuilding.

There is a VERY slight bow on one of the faces where the two halves come together.

If you picture the slender piece where the bypass is, it is bowed in slightly. This leaves a very slender gap where the two metal surfaces of the halves meet. (There is no gasket in the '81. It is a metal-to-metal connection.)

I'm not sure what sealant (if any) I could apply when I reassemble to help fill this gap. It is probably about the thickness of one or two sheets of paper. It is too thin to slide a playing card into it, but I can see a hint of daylight through it.

I have also thought of trying to remove the bow by applying pressure and heat. If I put the halves together, appled pressure with some vice grips, and added heat with a propane torch, is it possible that the bow, since it is so slight, will come out?

Thanks.

 

[jameskb2]

Re: Slighly Bent Cylinder Face.... Sealant?!?

You could face the part with fine grit sandpaper laid over a thick, flat piece of glass. I've done this with cylinder heads, it works great!

Lay the head surface down on your sandpaper (which is on the glass) and hone it slowly using a "figure 8" motion. Check it every so often to see progress. You won't have to remove much material, and you're done when you see scuffing on the highest point. (The last area to contact the paper) It'll be straight and smooth!

I use high temp RTV (black) silicone gasket sealer many times. I sealed my 3 horse power Evinrude's exhaust cover with it, no gasket. Doesn't leak a bit!

 

[Dhadley]

Re: Slighly Bent Cylinder Face.... Sealant?!?

Do not surface the front half or the block half!! Taking any material off either surface will change the line bore and change the main bearing holes.

What you're seeing is not uncommon. You'll have to use a straight edge and tap that area back in place. Tap and check with the straight edge. That area has to be perfectly flat so the Gel Seal will cure. Gel Seal will not cure in air, only in the absence of air.

 

[brettagostini]

Re: Slighly Bent Cylinder Face.... Sealant?!?

Dhadley, that makes sense.... using the straight edge and tapping. I'm guessing tapping with a heavy hammer... maybe using a long bolt to tap on.

Do you think applying heat would help the process? Again, the area that needs to move is the thin, pencil width section that runs along the bypass. So I'll actually have to get in behind it with the bolt and tap outwards.