Well as the title reads, I cant figure out why this keeps happening. Everytime i start my Z after its been off for an hour or more, it squeals something UGLY for about 15-20 seconds then stops.

I raised the car to go under to adjust the tensioners and realized that the AC tensionser was so loose on the belt that i could turn it with my fingers without applying much force.

After tightening it, i tried starting it and it didnt do much. Still squealed. I kept toying with it and wound up stripping the screw. (which i think might have been stripped already because i didnt really apply much force to anything).

I got frustrated and removed the entire tensioner and belt because i thought that was my problem. After doing so, leaving the single main belt as the only thing running, the problem got WORSE.

Without the AC belt on the crank pulley, and the AC tensioner taken off, the squeal lasts double the time and is twice as loud. The belt doesnt seem to have too much slack to the point where it should be making this noise.

I do have some aftermarket aluminum pulleys installed. I doubt this would have anything to do with this squeal because ive had them on the car since last october and this problem just started recently.

The single belt thats running is also brand new, it has less than 500 miles on it. If anyone has ANY idea what i can do to stop this squeal, you will earn 100 internets and my eternal gratitude. Pls halp

 

A squeal on a cold start is almost always caused by the longer main belt. The Nissan spec is to tighten the belt until a 22 lb force on the top run will only cause a 4.5mm deflection. (Somewhat tighter than you might think it should be). A new belt will work its way into the pulley groves after about 500 miles and may need a readjustment.

Use the search function on this site to get the exact specs. As Nissan gives a tighter spec (less deflection) for a new belt, than for one in service that just needs an adjustment. I calibrated my thumb on a bathroom scale for the 22 lb push needed.

 

Since i have to do this by guesstimation, is what would happen if say i overtighten the belt?

I know i wont do it too much as ill be looking for a 4mm deflection, but says its 3mm instead?

 

A new belt will tend to ‘run in’ a bit as it adapts to the wear pattern of the pulley groves (especially so with an aftermarket aluminum pulley). It is normal practice to set a new belt to a tighter spec, as it will soon run in and relax to the correct tension.

Just a guess, but maybe when the new belt was installed 500 miles ago it wasn’t given enough tension causing it to become very loose (squeal on start up). You can now treat this belt as an in-service belt (settled-in) and use the normal 4.5mm deflection @ 22 lb pressure setting.

When we did my belt we had two people. Me to supply a push on the top run of the belt and him to measure the deflection and set the adjustment. You don’t have to be super precise on this, but too much tension will be hard on all the bearings the belt runs against and too little will squeal.

Just another guess, but do check any after-market aluminum pulleys for damage or glazing from the slipping belt.

 

Cheap fix. Turn off all air until the motor warms and the metal expands. Or have the tension set correctly.