LS Belt Alignment & Troubleshooting Guide

1. Check Belt Tension (Automatic Tensioner)

This can cause the belt to move forward on one pulley only, or cause the belt to jump off. Look at the tabs on the tensioner. With belt on, the pointer should sit near center of the sweep. If it's towards the far end → belt is too long, not enough swing to hold tension. Replace with a shorter length belt. If you have a fast reving engine then a manual belt tensioner will fix most issues. Ask us for which one you need (to set manual tension - set 1/64" of deflection per inch belt span between pulleys. Example: 15" span → ~¼" deflection)

2. Find the Problem Pulley

Stand in front of the engine, looking at the pulleys:
Crank pulley = clockwise rotation while standing in front of the engine.
Water pump = counterclockwise rotation.

To locate the misaligned pulley:
Watch where the belt jumps one rib forward/backward (crank engine without starting). The pulley just before that point (in rotation direction) is the one causing the problem. Example: If the crank pulley shows the belt forward 1 rib, the issue is the pulley that feeds the belt onto the crank.

3. Check Power Steering Pulley

Must be fully seated on the shaft. (LS1 pulley bottoms out on the shaft. Truck pulleys sit flush with shaft). Must be the exact pulley for that pump model. These are commonly mismatched and are not compatible, even if it presses onto the pump. Reference to see the visual differences in the pump and pulleys: ictbillet.com > Guides > LS Guides > Power Steering

4. Check Pulley Alignment

Use a laser alignment tool (ex. Dayco 93874) from your local parts store to compare pulley grooves match up with each other. Hold the tool on each pulley and shine the laser to various other pulleys. Also hold the tool in place while you rotate the pulley underneath it to see if the pulley is bent (laser will wonder back and forth if so). Plastic pulleys can become cracked or chipped and cause issues.

Adjust spacers or brackets if misaligned. It helps sometime to remove just one of the bolts out of a single accessory bracket. Lets say the alternator bracket we are looking at. With the belt on all the accessories with it tensioned. If you remove just one bolt from the bracket, then the bracket springs forward, the there could be an issue with the wrong height of spacer below this point. Put this bolt back in then repeat this process on other bolts.

5. Verify Spacer Lengths

Spacer dimensions are available here. Check each spacer matches the instructions and is installed in the correct location.

6. If Problems Continue

Send us detailed photos of the entire accessory setup (front view of all pulleys (so we can determine brand, offset, and model numbers used), crank, water pump, power steering, accessories, belt tensioner tab location).

We can send out the laser alignment tool (deposit required until returned with ICT provided return label). We may upgrade the bracket if there are options available for that location. Next day shipping will be provided for replacements in the continental U.S.

7. Misc

Isolate the issue if more than one bracket is connected to each other, then remove connecting bolts to see if this issue is fixed. Measure with ruler across the crankshaft pulley face and use a 6" scale to measure to each pulley center to look for any pulley in the wrong position.