So I just snapped a bolt off in my brand new 0 mile, MHI E316G... Its for the oil drain. So after snapping 2 easy outs, and 3 standard drill bits i have a decent sized hole. So I went out to Harbor Fright and got a tap and die set. I started using a M6x1.00 tap, went in decently easy, pulled it out and had a perfect threaded hole. Now if I would have stopped at that, I wouldn't be making this thread... I thought that I should tap it alittle further in, well I stripped all the threads that I just made. So then I tried a M7x1.00 since the hole is bigger, well that made 2 threads and striped. The last one I tried was the M8x1.00, its doing the same thing.

So before I completely destroy my new turbo, how the hell do you tap cast iron correctly without just making the hole bigger?

 

Find a bolt that fits your last tap M8x1.00.. Make sure when your tapping that everything is straight and smooth. go very easy with it.. I recently tapped 3 holes in my turbo, to 02 housing holes. just go slow with it and use the correct sizes. it should be easy if you take your time and go very slow. good luck

 

sounds like your taps are bottoming out. you need to use flat bottom tap, for this

 

Lancerman, they are flat bottom taps. They dont come to a point.

 

All taps are flat on the bottom - what he is referring to is a bottoming tap that has thread cutting ability for blind holes. They are not as common. Most tap & die sets are tapered taps. As the tap reaches the end it tapers and the threads are not cut fully.

 

Also make sure you are backing the tap out after you make each thread. I do like half a turn in, then one whole turn out to clean out the tap.

Or if you wanna use the original bolt, get a helicoil kit.

 

I would replace the housing at this point if it were my turbo. sounds like this one is ruined. I have some nice low mile ones here if you want to fix this correctly.

 

+1 ^

 

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