Fan Clutch Info...

I bought a 2003 PreRunner 3.4L Auto about 9 months ago and lately something on the accessory drive (I'm assuming) is chirping and sqealing. When it started it would only make noise when the engine was cold and would go away under moderate-heavy acceleration, be quieter but still audible under light accel and cruise and loudest under off gas deceleration. Lately it's lasting longer, but still eventiually goes away after fully warmed up and then some time, otherwise basically the same only louder.

By just using my ear and trying to locate the source of the noise it seems like the fan clutch is the source. I havn't been able to figure a good way to test it short of removing it from the crank. I examined the maintenance records which are quite thorough and found no evidence that it had ever been replaced, only possibilities are that the dealer replaced it during one of the scheduled maintenance events at 30k, 60k, 90k, etc. I figured it was unlikely to be a scheduled replacement part. So I have decided to replace the fan clutch and the accessory drive belts. My question is:

Is AISIN the OEM fan clutch manufacturer? And how do I know if I have the tow package or not? If I get a fan clutch designed for tow package will I have any issues if I don't have the tow package, specifically with fitment? Like a shorter fan mount shaft for thicker radiator clearance, etc?

Any other items I should replace/inspect while I have the fan off and belts off? Are there any acc drive tensioners that typically go bad? Belts were done about 70k miles ago, best I can tell from the records. No mention of any pulleys being changed.

Thanks for any info and help.

 

Looks like the manual and fan clutch instructions recommend replacing the water pump at the same time. Apparently that requires removing the timing belt. If the 3.4 (5VZ-FE?) is a non-interference engine, I may just do the fan clutch and wait to do the water pump until I am ready to do the timing belt.

Any input on this decision?

 

While it's no guarantee, your symptoms are textbook for failing bearings in the 3.4 "fan support bracket" (FSB). It's the casting the fan clutch bolts to. Bad ones sound like a squeaking squealing belt that quiets down on warm up buts gets worse over time. The water pump has nothing to do with it and not related in any way.
Use a stethoscope, real or improvised to isolate the sound. Fan clutches typically don't squeak/squeal.
The FSB is made by Aisin and available thru aftermarket parts houses, Toyota only sells it as an assembly including the fan clutch, pulleys and the FSB for mega$$$. Do not get a non Aisin FSB.

The 3.4 had 2 interchangeable fan clutches, also by Aisin. "Standard" has an orange hub and "heavy duty" is green. I believe the green "heavy duty" clutch is now the only service replacement (from Toyota). Most of the 4wd trucks came with them new, with or with out the dealer/regional installed tow hitch kit.

Fan support bracket on left, also called a "false water pump". Touch (carefully) the stethoscope to the ribbed portion of the "snout". The bearing itself is a proprietary combination of ball/roller bearings, not available separately. The pictured fan clutch has the green hub.

 

Wow. Excellent information! Thank you much! I will get the fsb assy or just the bearing if I can find it. Is pulling the fsb assy required to change the bearing out can it be done with it attached to the engine?

 

Go back and read the second to last sentence in my post.

I would "listen" to it first to make sure it's the culprit. A "mechanics" stethoscope is $5 at Harbor Freight and a very handy tool. Or improvise, take a long screwdriver and touch the tip to the FSB. Put your ear right up tight to the end of the handle. Even a stick, like a section of broom handle will do the trick as will a piece of hose.

 

Oh, can't believe I missed that.

I'm a mechanic, on aircraft, but am familiar with a mechanic stethoscope and will verify that is the source of the noise.

Thanks again!

 

I recently changed mine, it was much noisier on humid days. Not hard to change, might as well put on new belts since you have to remove them to change that FSB.

 

That's the plan this weekend. Have all the parts ready to go.

 

I'll be damned. My truck sounds horrible on cold mornings, but it cheers up as the engine warms. I'll be getting a stethoscope and checking this one, too. Thanks!

Edit: Wow, that thing is over $100 at rock auto.

 

about 650 from the dealer