97' Mazda 626 LX

Had belts replaced about 2-3 months ago, just recently they started squeaking on startup, but will go away permanently at about 2500 rpm. I'm assuming they are loose and need to be tightened. Any other ideas?

When a belt needs to be tightened to 40 ft./lbs, I'm assuming that doesn't mean 40lbs on the torque wrench, correct?

Thanks,
Eric

 

Dirt, oil, grease, or adjustment. New v-belts especially stretch during the first few months and could now be loose. Or, if they are serpentine belts, take them off and wash them in a mid dish detergent and water. I'm sure the same would work with a traditional v-belts as well.

 

Those accessory drive belts are a pain. They are ridged to increase the load bearing area, but the ridges in the pulleys/ idlers get clogged by the residue left behind from the worn out belt, and the new one stretches, but also cleans out the residue left behind from the old belt and then bed in as well, so they go slack pretty quickly.
Another problem is with the torquing. The threads on the torquing screws get dirty and rusty, so when you measure the torque, you're really measuring the combined torque due to the force applied to the belts plus the force needed to turn the crudded up threads on the tensioner screw. The net result is a tendency to undertension the belts, hence the early morning squeal.
I'm lazy, so I don't like to remove the belts to clean them up.
First, I take an old toothbrush, clean the tensioner threads with dunk or gunk, and give them a little squirt of WD40 or Releasol, and work them to and fro so the tensioner screws runs freely in the nuts. Then, with a toothbrush or paint brush, I clean up the belts and pulley grooves, finishing off with a brass bristle brush. For this cleaning I use methyl alcohol (methyl hydrate,same thing) because it's a good degreaser, it's cheap, safe for belts and hoses, leaves no residue, doesn't stink, and is totally water soluble. After a water wash down, I reset the belt tensions, knowing the system is clean and that dirty tensioner screws are not giving misleading torques.
You should get this situation sorted out before the weather gets too hot though, because once you start using your air conditioner, that compressor puts a big load on its drive belt.

 

So, just to confirm...tension on a belt CAN be measured by torquing on a "clean" tensioner bolt?

Thanks for the tips

 

A torque wrench has a calibrated graduated scale and a moving pointer on it. The scale is marked at one end with the units it's measuring, Nm (Newton meters) if metric, Lb.F (pounds feet) if imperial.
If you are using an ordinary (uncalibrated) socket drive, you have to measure the distance from the center of the socket to the point where the measured force ( using a spring balance for example), is applied.
As an example, suppose a 50Lb. force is applied at a distance 8 inches out from the socket. Then the torque is 50 x 8/12 Lb.ft. i.e. 33.3 Lb.ft.of torque.

Another common way to set belt tensions is by the mid-point deflection for a given applied force. My engine is a 1.8L FP, and my mid-point deflections for 10 Kg. force, are 10 mm. on the alternator belt, measured between the alternator and water pump, and 11 mm. on the power steering hydraulic pump, measured between the crankshaft and the hydraulic pump.
These measurements must be done with the engine cold or cooled down for at least 30 minutes.
Your car will probably have different values, so you'll have to look them up.