Lightweight Pulley

[Jay666]

I will personally never buy a crank pulley again. This was an agency power L/W Crank Pulley that was stripped apart and cracked. The cracked pulley then tore apart my crank case oil seal so my engine was leaking lots of oil. Luckily I kept the stock pulley. I replaced the oil seal put the stock pulley on and it hasn't been a problem. Knowing that it was an aftermarket part that I put on that could have destroyed my engine and voided my warranty was too nerve-racking for me to risk something like that again.
Attachment 1549

Wow, that SUCKS.

[bwood87]

That suxx there bwood87. Suppose it could have been worse. Looks like Agency Power's LW pulley is on the crap list. What were you doing when it cracked? This appears to be the first failure of a LW crank pulley due to fatigue stress fracture that I have heard of. Of course, I don't know everything. I just may have to swap mine out for a racing dampner for my race motor.

I was driving to work when it cracked. I was stopped at a red light at 6 in the morning, I started to drive and I heard the noise, my car kinda like shuttered and then my check engine light went on. I had the pulley one for a few months before it happened. AP said its possible that the bolt loosened up and the pulley started to wobble and then cracked, but I used thread locker and torqued to spec which i think was 150lbs.

[navylife59]

133 ft-lbs torque for stock bolt and 150 ft-lbs for the strengthened TRD S/C bolt to be exact. Was there any sign of elongation and/or spinning of the bolt hole of the pulley? If not, then it is not likely to be from a loose bolt. You had it on there too short for it to be from corrosion. Sounds like a definite stress fracture. This would have been a defect in workmanship and/or materials.

[bwood87]

133 ft-lbs torque for stock bolt and 150 ft-lbs for the strengthened TRD S/C bolt to be exact. Was there any sign of elongation and/or spinning of the bolt hole of the pulley? If not, then it is not likely to be from a loose bolt. You had it on there too short for it to be from corrosion. Sounds like a definite stress fracture. This would have been a defect in workmanship and/or materials.

This is the best shot of the inside. I would take more but I threw it out about a month ago when cleaning out my closet.

[Jay666]

That's pretty brutal.

[navylife59]

The optical occlusion caused by the lensing effect of your camera makes it difficult to get an accurate representation of the damage. What I can garner is what looks like a damaged keyway and galling from spinning on the crank snout. Were you able to recover your key? It is possible that it actually failed causing damage the pulley's keyway. This would not put the pulley at fault. On the other hand, the keyway may have been machined with too loose a tolerance which would allow the key, which is a harder material, to cause fretting corrosion. The wrong alloy type or hardness will produce the same results. Waiting for more pics.

[punk2m1d]

What brand is best known for quality parts? I've seen OBX, Agency Power, and NST. The OBXs don't say they're anodized, so I'm straying away form them. Although I do like that they come in blue.

[navylife59]

In order of preference:
NST
Agency
OBX

NST has the highest quality and no known defect/complaints that I know of. You are correct, the pulley needs to be anodized or it will be damaged by corrosion, especially if you live in an area that salts the roads or by the ocean.

[Jay666]

I have the NST red anodized, as they came the highest recommended. More expensive, but vey happy with them.

They also have a very user friendly link on their website that will tell you which belt you need to buy for which pulley replace situation, etc. Very easy. Very friendly dudes working there.

I ordered one of the wrong ones by mistake (fat finger) when I purchased my set and called them up. They were very friendly and easily accommodated my error. Highly recommend them.

[punk2m1d]

Awesome. Thanks. If I just buy a light weight replacement the belt should be the same size right? Can't I just use the belt I have now?

[Jay666]

It depends on what you are replacing. Use the guide on their site here. It explains all of that. It tells you what belts you will need for which replacements:

NST - The Leader In Scion tC Pulleys

[navylife59]

No belt change needed for changing same size (no under/over driven) pullies.

[StreetBrawler89]

Just a heads up the change is a two person job, although person two can be a girlfriend or someone with very little mechanical knowledge.

[shamshe]

This is what i see on NST's site:

20% Underdrive Crank Pulley

CR-Lite Crank Pulley

20% Overdrive Alternator

WP-Lite Water Pump

20% Alternator &
WP-Lite Water Pump KIT

Sooo which ones do you recommend getting?

[navylife59]

Unless you are running some heavy amplifiers use the standard LW alternator. Only run an underdrive crank pulley for a dedicated race car. It slows up all accessories drive on the serpentine belt, therefore, the alternator, water pump, power steering, and a/c compressor will run slower. This can cause problems at low engine speeds/idle like slow charging, engine overheating, and the a/c not cooling enough at those speeds.

[shamshe]

so basically if i got the crank pulley the water pump pulley, i dont see the light alternator pulley though.....

[navylife59]

You can call NST and tell them what you want. They will hook you up. Not changing the ratios for any of the pullies allows you to save money by using your OEM serpentine belt. Just tell them that you want all 3 LW pullies but the same ratio as the OEM pullies.

[shamshe]

thank you very much! i will call em up

[navylife59]

You are welcome.