zillakilla02 Posted June 7, 2015 Report Share Posted June 7, 2015 So I made my leakdown tester today so that i can get this thing tore apart and see how much damage im dealing with but anyways it turned out awesome thanks to the sticky how to on this website but the results have me needing more advice! I pumped it up to 6psi and it seemed to be holding but ever so slowly starts dropping and seemed to be dropping faster than it should. I would say 5 minutes and it's down to zero. I sprayed everything down and only leak I could find is on the right side intake part of cylinder where those stupid little holes are on a cub cyl from I guess the factory drilling and tapping the bolt holes for your intake manifold... I was told these holes were normal for a cub but the top right one is leaking. None of the other little holes are. It will slowly bubble out of there and my right cylinder is the one I had most problems with and couldn't get to run right and also was the one backfiring. So I'm guessing this was enough of a leak to make it run lean? But what I don't get is how that started to leak if that hole isn't supposed to go all the way thru into the intake tract. How should I repair it? Will it need to be welded or is there other options like filling it in with some sort of sealer that holds up to gasoline? I'll have the cylinder off so if it needs to be welded then so be it I weld aluminum at work all the time just not cast so that's why I want to know my options. Thanks again Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 7, 2015 Author Report Share Posted June 7, 2015 https://youtu.be/SWaMKYWWLr0 Here's a video I took of the leak so you can see the bubbles coming out of that hole Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted June 7, 2015 Report Share Posted June 7, 2015 It's probably leaking around the gasket, then around the bolt. If the hole dosen't go into the intake, that's the only way it could leak. If you remove the reed blocks and you see a hole on the inside, I'd use morose A/B. 1 Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 7, 2015 Report Share Posted June 7, 2015 Clean hole with brake clean, fill with Yama bond. Have manifold assembled with bolt in as not to use too much. 1 Quote Link to comment Share on other sites More sharing options...
BANSHEE HP Posted June 7, 2015 Report Share Posted June 7, 2015 Is that the bolt hole? It doesn't look like it, looks like it's in the intake track not the intake flange bolt boss 1 Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 7, 2015 Report Share Posted June 7, 2015 After plugging hole retest, it then might show elsewhere 1 Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 7, 2015 Author Report Share Posted June 7, 2015 Yeah I was told it's from the factory drilling out the holes for the intake bolts... I'll check out the inside when I pull it apart to do pistons. So Yama bond is fuel resistant? I had some high temp red rtv but I see that's not supposed to be used in contact with gas Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted June 7, 2015 Report Share Posted June 7, 2015 Yamabond or just get import grey at auto parts store. Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 7, 2015 Author Report Share Posted June 7, 2015 Ok thanks alot Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 8, 2015 Author Report Share Posted June 8, 2015 It's probably leaking around the gasket, then around the bolt. If the hole dosen't go into the intake, that's the only way it could leak. If you remove the reed blocks and you see a hole on the inside, I'd use morose A/B. You were right man it is leaking past the gasket and out the threads of the bolt hole... the surface for the gasket to seal on there is extremely thin so should I use any extra sealant on the gasket itself too? They are brand new gaskets Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted June 8, 2015 Report Share Posted June 8, 2015 You were right man it is leaking past the gasket and out the threads of the bolt hole... the surface for the gasket to seal on there is extremely thin so should I use any extra sealant on the gasket itself too? They are brand new gasketsYep. The most inside edge of them has very little meat for sealing surface. Use thick , high quality gaskets, with a very thin smearing of import grey usually does the trick. Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 8, 2015 Author Report Share Posted June 8, 2015 Yep. The most inside edge of them has very little meat for sealing surface. Use thick , high quality gaskets, with a very thin smearing of import grey usually does the trick. Ok will do thanks alot. I got brand new gaskets with my new intake recently but maybe they're cheaper gaskets. I'll have to pick up some better quality Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted June 8, 2015 Report Share Posted June 8, 2015 Ok will do thanks alot. I got brand new gaskets with my new intake recently but maybe they're cheaper gaskets. I'll have to pick up some better qualityThey might be fine. Also, I like to lightly tighten the reeds while the sealant is curing, let it set a little bit, THEN torque to spec . Sometimes the sealant will let the gasket slip if you apply too much torque while it's still uncured. 1 Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted June 8, 2015 Report Share Posted June 8, 2015 AFM gaskets. Couple different brands out there, but even the worst are better then the best paper gaskets. 1 Quote Link to comment Share on other sites More sharing options...
zillakilla02 Posted June 8, 2015 Author Report Share Posted June 8, 2015 Ok sounds good I'll look into them I don't mind paying a little more for better quality this is a mistake I don't ever want to make again!! Quote Link to comment Share on other sites More sharing options...
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