Cleaning head bolt shafts

Question

I am about to put my two cylinder heads back in and did some preliminary finger fitting of a bolt in every one of the 16 shafts to make sure it goes in smoothly, i.e. no gunk/debris impeding the fit. As it turns out, all but one are fine and clean and one is not quite. I can twist a bolt all the way in to the same level of the bolt only using a ratchet but not with fingers and it feels like there is something like residue or a piece of gasket maker inside. I tried blowing it out with an air nozzle (which is what I did with every other one anyway) but that didn't work.

Should I use a metal tube/pipe brush like this? I am concerned about a string falling off and staying in the shaft, which would then jeopardize the torque.

Answer 1

Your best bet is to use a thread chasing tap. It is the surest way to get the threads clean. The brushes you show work great for cleaning oil passages and the like, but really don't clean the threads. Here's an example:

You'll note a few of things about them:

• There's very little taper at the end, unlike a tap used to cut threads.
• The nose is not pointed, but flat. This is so you can get to the bottom of the hole.
• The flutes are really broad. This is to carry the garbage back out of the hole with it.

You can get these in SAE or Metric, as well as in several different styles/lengths.