The Hilti series of hammer drills are made for tough work with concrete and stone. It really surprised me when
my Hilti TE60 failed to hammer after I had taken it out of the tools cabinet. That is: it's very unusual for
tools to fail in storage. I called Hilti support to ask for advice because something like this is not normal.
However, they did not have any tips or suggestions. They just wanted me to bring it to them for repair.
I learned from other Hilti Hammer Drill owners that this is a very common problem! The knocker that flies back
and forth under changing air pressure can get stuck in cold gummed-up grease. As a result the machine will no longer hammer. In fact, Hilti might have known about this problem area ever since they wrote the manual. They mention that the hammer drill will not hammer in
very cold weather without explaining the cause. There is no temperature sensor in this machine. It was not cold when I had the problem but over time
some grease that you apply to the back of the tool penetrates up to the knocker and the knocker gets stuck. Add a little
bit of fine cement dust to the mix and you understand why knocker might not "fly anymore".
This is not a pure "cold weather problem" as the Hilti manual suggests. It can be caused by dirty grease, too much grease, old grease. It can always happen and just warming up the machine to room temperature might not fix it.
There is however a simple fix: make sure the drill hammer is warm (room temperature), insert the chisel tool, and slam
the hammer down onto a hard rock as shown in the picture. The shock created by the chisel hitting the rock will loosen the
knocker. The machine can handle this kind of rough treatment.
slam the hammer drill down with the chisle onto a hard rock to make it work again
A way to prevent this problem is to put once in a while some oil into the tool holder instead of grase when you insert the tool (drill or chisel). I recommend also to clean out once in a while old dirty grease from the tool holder and rinse the inside of the tool holder with WD40 spray.
It's really strange that you have to learn this from other hilti hammer drill owners and the company has no advice when you ask them.
