3SFE Timing Belt Tensioner pulley adjustment

[Montanahelp]

I'm replaceing the timing belt on my 1988 4 cylinder. I have the belt back on and the timing looks good. Is there any adjustment on the belt tensioner pulley? Or do I just torque it when it is applying pressure to the belt?

[toyomoho]

With belt is installed, loosen idle pulley bolt. Rotate the crank clockwise by hand 2-times. Recheck timing marks. Tighten the idle pulley bolt (31ft-lb). The manual says nothing about applying pressure to the belt.

[fredk]

if its too loose it will flap, if too tight it will sing like a blower, i run mine a little tight and it sings, but its not going anywhere

[Digger1]

This timing belt tensioning technique works for a 5S-FE (my car is in my signature). So, for the 3S-FE, YMMV:

As per the instructions in the FSM and Haynes manual, I positioned the crank at TDC and positioned the camshaft at the TDC position. However, when installing the belt, I could not get rid of some excess slack in the front of the belt (the part that runs forward from the top of the camshaft pulley to the waterpump pulley). I could not pull the belt any tighter, since the most I could pull it toward the camshaft pulley was only about half a tooth of belt length.

So, here is what I did to remedy the situation:

I pulled the belt back off of the camshaft pulley. Note that the tensioner pulley was temporarily fixed in the "loose" position, as per earlier instructions in the repair manuals. I then turned the crankshaft 5 degrees counterclockwise. It was now at 5 degrees BTDC. I then put the belt back on the camshaft pulley. The camshaft pulley was still at the TDC position.

I then rotated the crankshaft 5 degrees clockwise to TDC and checked my alignment. Voila! Spot on! The small rotation of the crankshaft had merely taken up slack in the timing belt and did not move the camshaft pulley. Just to be sure, I rotated the crank through 720 degrees and checked my alignment again. Spot on! Ever skeptical, I cranked 'er up (after setting the tensioner pulley as per the instructions) and ran the engine for a few minutes without the upper timing belt cover in place. I shut 'er down and checked the alignment again. Spot on!

Best of all, the forward portion of the timing belt was now properly tight.