Try unplugging the PCV valve - may be clogged ?
Just a guess
Sounds like a pack of dogs yelping. Hey seriously, are you saying it stops when the oil cap is off???
There should not be vacuum in the crankcase. The front of the valve cover has a pcv hose on it. Check that
McCaws, RabTech -- thanks for the pointers! These were right on the money. I had also checked the EcoTech forums for similar symptoms and found:
http://www.ecotecforum.com/for…tops-when-oil-cap-removed
I had recently installed a small air/oil separator into the breather line to prevent oil accumulation in the intake manifold. It's tiny in-line "filter" eventually got saturated with oil and created a restriction. It only takes a few drops of oil to saturate this type of filter...
I opted to remove the tiny in-line filter and use some SS steelwool in the air/oil separator chamber instead to eliminate any flow restrictions as oil accumulated.
Yay! No warranty trip to the dealer!
...and this is how it should be and we thank you.
Too many folks jump on forums with a new problem thread, get helpful advice, find a solution to that problem, and then fail to return the courtesy of a thank you and a reply of the fix.
This then leaves the thread hanging and the next person with the same problem scratching his watch and winding his @$$ wondering WTH.
Kudo's to @rabtech, @MACAWS, and @gearhead.
dat's how it's done! 
Display MoreMcCaws, RabTech -- thanks for the pointers! These were right on the money. I had also checked the EcoTech forums for similar symptoms and found:
http://www.ecotecforum.com/for…tops-when-oil-cap-removed
I had recently installed a small air/oil separator into the breather line to prevent oil accumulation in the intake manifold. It's tiny in-line "filter" eventually got saturated with oil and created a restriction. It only takes a few drops of oil to saturate this type of filter...
I opted to remove the tiny in-line filter and use some SS steelwool in the air/oil separator chamber instead to eliminate any flow restrictions as oil accumulated.
Yay! No warranty trip to the dealer!
Team work!
Thanks for updating us and pointing out another area that should be routinely checked
Sling On
I have seen several people adding catch cans and I understand the purpose. Mine never has burped a single drop of oil. I just have a tiny k&n filter plugged into that valve cover port. Are y'all seeing a bunch of oil?
I had the exact same issue with mine, completly stock, had 800 miles on it when it happened:
http://www.slingshotforums.com…/weird-engine-noise.5966/
I had posted about his on the dark side, never really got a good answer. Still never really understood what caused this, and when I took my engine apart recentyl, I had found this is one of the cam oil passage:
I had assumed this was the reason of the noise, maybe it had blocked the oil passage.
My noise went away on its own, never did it again, real weird, but maybe I had a loose hose somewhere that I reconnected when trying to find the issue...
Good find. Now I know what my issue was.
I have seen several people adding catch cans and I understand the purpose. Mine never has burped a single drop of oil. I just have a tiny k&n filter plugged into that valve cover port. Are y'all seeing a bunch of oil?
Rabtech - I haven't seen any oil - you can smell oil a bit when you are hard on the gas, I am guessing it is vapor coming thru the filter - I have the same as you. I will be adding a catch can as I do not see any downside.
Reach out to Bill from Hahn RaceCraft he and I discussed it and he had a few good comments / ideas
I know!
I had the exact same issue with mine, completly stock, had 800 miles on it when it happened:
http://www.slingshotforums.com…/weird-engine-noise.5966/
Why did you take the engine apart cause of the noise?
Non, I am doing this for the greater good of human kind... Oh ah pushing 15 psi of boost into it has a bit to do about this too lol
Good thing that piece of casting stopped right there. You would hear a bad noise as your cam started to tear up. 
