these are two different things... taps are for...tapping a hole. chasers are for...cleaning up an already threaded hole.
taps can be used to clean up the threads too, what do you think was used to thread the hole to begin with??? tap... anyways, sounds like repair job maybe required with insert/heli coil...... take your time and good luck!
"A thread cutting tap is designed to cut threads. It will never engage the already cut threads in the same manner every time. You can take a new drilled and tapped hole and run the tap back through it and it will remove more metal. It won’t only remove material from one side; it will remove it from the entire circumference of the hole. It is almost impossible (by hand) to get the tap lined up in the exact same orientation to retap a hole. In a poor example that I can do like this the first time you cut the threads they will look like this > <, every subsequent time you run a thread cutting tap through the hole it will remove the point of the threads and round them off, reducing your thread depth . This is from the tap being slightly out of alignment with the original threads and it is cutting the threads in the alignment it is at now. That is the material that is getting removed. What are you wanting to clean out? If its a non stressed part then using a normal tap wont be a really big deal. I would not use a normal tap for any critical fastener. Something like an intake or accessory bolt holes is no big deal. But definitely use a thread chaser for something like main bearing caps or head bolt holes. Just bear in mind that threads cleaned with a normal tap wont be able to take the same torque load due to the reduced thread depth and contact area......"
ok so I didnt want to start up another thread for this but I got it to work!! now I ran into another problem...im trying to get my upper radiator hose connected and cant get it into it cause the hose under neath it is getting in the way...(just my luck) anyways was wondering if anyone know if I can use the 5.0 outlet on it so it goes upwards instead of at a angle.. thankss