T43 makes strange noise for about 5 seconds during start

[jhui]

I am trying to rebuild this T43 for our company. It is making a loud noise that appears to be a fan. What appears strange is the loud noise only lasts for the first 5 seconds or so and then noise level returns normal. I know what the normal noise level is because we have another working unit of the same model.

To locate the source of the noise I turned the machine upside down and used my thumb to press against the plastic (on the bottom of the machine) during start up. There is a rectangle drawn on the bottom of the machine. Inside the rectangle there are 4 signs looking like 4 screws of different sizes. The noise comes from an area on the NE (north east) side from this "rectangle". For the purpose of telling you how the machine was oriented, the touch pad is on SW (South West) of the rectangle.

Other than this noise it appears the machine just works normal after I fit it with a new hard disk and got Windows installed. First, should I worry about this noise?

If not. I hope to find someone who is familar with the repair of this model and can possibly tell me if I can fix this problem myself.

[dr_st]

On startup, every Thinkpad I know spins the fan very fast for a few seconds (I presume this is the fan test). Then it returns to automatically controlled mode where it spins faster or slower depending on CPU temperature.

Fans sometimes get louder than normal when they are clogged with dust or when they are close to the end of their cycle.

What you can do is see if perhaps the fan could use some cleaning. For this you would need to remove the keyboard (there exist appropriately marked screws at the bottom of the machine (3 for 15" model, 4 for 14" model), and the fan will be exposed.

You try to blow into it either yourself or using a can of compressed air. If you do so, it is advised to hold the fan blades from moving (toothpick may help) while blowing, so as to prevent overspinning the fan (which can damage the motor).

If cleaning does not resolve the noise problem, there is a good chance the fan is on its dying breaths, however I assume it still works. You may opt to replace it now, or wait until it actually dies (at some point it will give a 'Fan Error' when you turn the laptop on). Either way is fine, depending on how critical the machine is to you and whether you can absorb a bit of downtime later down the road when the fan dies.