Fuel Leaking From Power Head

Dblanton, I know this is a very old thread, and I hope I get a reply. I have the exact same problem with my 77 Evinrude. I must know how, or what you used to seal your crankcase halves? I would also like to know more info on piston placement when putting them back together.

 

a reply 13 years in the making ! It was pretty easy to test for crankcase leaks on the mating surfaces. I recall fixing one leak using epoxy, dismantling the powerhead being too much like hard work.

 

There was some red goo used to seal it, jagger. But you have to dismantle to employ that. Like I said, I got lazy, prepared the area where the leak was, and used an epoxy. Fixed it. If you have any ambitions to dismantle the engine, the workshop manual is indispensable.

 

I gotta say I’m pretty exited to get a reply!
I never thought of using an epoxy. I was planning on doing somthing very similar. Using red RTV high temp Sealant around the bottom side of the crank case. I also bought all new seals/gaskets for the powerhead.
My repair manual has very detailed instructions on taking apart the crank case half’s ,but as summer approaches I didn’t think I would have the time; so I was looking for a temporary fix if it is the crank case leaking after all.
I will keep you posted if your interested. Thanks!

 

It isn't worth pulling down powerheads, without doing a proper re-build, which involves making sure all dimensions of pistons and cylinders are up to spec, checking bearing surfaces for pitting , replacing rings and bearings etc. You may even need a rebore and oversize pistons. It generally is not worth it. If you suspect a leak, you can sometimes hear a whistle, or by holding a piece of tissue paper with a forceps along the break line, can see where it is leaking. I would definitely try an external fix, and an epoxy that can grip aluminium well, should do the job, if the surface is properly repaired, and scrupulously free of oil. But, there may be another goo that works as well, you could try a technical assistance line with a big manufacturer of such product.

 

Don't use RTV. Fuel dissolves it. You need a sealant that is fuel proof. The proper way to seal the crankcase halves is to open up the block and then clean the mating surfaces, and then use Loctite case sealant. Use very little of the sealant. You want to spread a very thin layer, you want to barely be able to see it. If you use too much it will spread the cases and that's not good. The sealant cures anaerobically so it cures once you put it together.

If you don't open the cases and do it right, you can try to seal it with epoxy or some other sealant. First you have to clean the area well with Brakeclean and squirt some thru crack. You've got oil from the case in the crack and if you don't clean it out nothing is going to stick in there. I've had good luck putting a small blob of the Loctite case sealant where I identified the leak was, and then, using the a vacuum pump and sucking down the case for a few moments to suck the sealant into the crack. Only run the vacuum for as long as it takes for you to see the blob start to decrease in size and you will have sucked the sealant into the crack. Stop there, if you keep sucking on the case you'll suck the sealant through and have an open crack again. As I see the sealant blob start to get sucked into the crack, I shut the vacuum off and let it set.