Tom57

Has anyone replaced only the bearings in the belt tensioner and idler pulleys on the 430 - with high-quality, OEM or equivalent bearings? What are the part numbers? Others with 1st & 2nd Gen LS have replaced just the bearings - very inexpensively > https://www.clublexus.com/forums/ls-...t-numbers.html. Are the idler and tensioner pulley bearings on the 1st / 2nd Gen LS the same for the 3rd Gen?

The belt tensioner pulley can be replaced without replacing the complete tensioner assembly. The Lexus tensioner pulley is part (#16603-0W030) ($63 list) and is made by Dayco. I cross-referenced to Dayco pulley #89026 which can be had for ~ $20 with a little search effort.

Edit: The correct replacement tensioner pulley is Dayco 89006 (see posts below).

Tom57

Update: The correct Dayco serpentine belt tensioner replacement pulley (which is the OEM manufacturer) shows part # 89026 on many, many online compatibility charts. That is, in fact, an error. The correct Dayco replacement tensioner pulley is part # 89006.

The bearing in the Dayco/OEM tensioner pulley is a high-quality NTN brand - Made in Japan. If you have a bearing press (or access to one), the bearing is NTN part # 6203LU. The pulley with bearing is ~ $20 online; an NTN, Naichi or similar bearing only can also be had online for ~$10. You get what you pay for with bearings; don't buy the cheap one.

Tom57

This post will save you $$ when it's time to replace the idler and/or tensioner pulley(s) when they're squeeling and chirping:

Idler Pulley & Bearing:

The current Lexus catalog idler pulley replacement is a Dayco brand (#89154). Apparently, the same idler pulley is used in 2nd Gen ('95 - '97) LS - (shared Lexus part #16604-0F010 with 2nd & 3rd Gen LS). (Gates pulley #36026 same). The Dayco pulley is available online for the low $40's. The idler pulley lists for $63 + tax/shipping at Lexus.

The original idler pulley bearing in the '01 is NSK #BD20-15DUL. Bearing size: 37 mm O.D. x 12 mm I.D. x 15 mm width. This bearing size is not generally available (anymore). In fact, the Dayco (#89154) replacement pulley has a different bearing than the original > #6203RS, and a different size, 17 mm I.D. x 12 mm width. The newer replacement pulley bearing also has flange reducer bushings installed on each side of the 6203 RS bearing to bring the final dimensions of the bearing with bushings to 12 mm I.D. x 15 mm width (equal to OE sizes).

Problem: the original pulley bearing may not have the flange bushings that you'd need to re-use if you were going to replace just the bearing. Check the idler pulley bearing to see if it has flange bushings. If it does, you could order a replacement bearing and install it with the bushings.

Tensioner Pulley & Bearing:

Tensioner pulley replacement in 3rd Gen LS is is Lexus #16603-0W030. Websites incorrectly show Dayco #89026 as the replacement tensioner pulley - the #89026 pulley is not correct - doesn't fit.

The Dayco #89006 pulley with high-quality bearing is available online for as low as +/- $15. This is far better than buying a whole new Lexus tensioner pulley ($67+ tax/shipping), or worse, the tensioner pulley and bracket assembly at Lexus for list price of $70 + tax/shipping.

You only need a new bearing in the original tensioner pulley. (You don't need a new bracket, nor do you need the steel portion of the pulley.) Bearing in the original tensioner pulley is NTN brand #6203LU. Bearing size: 40 mm O.D. x 17 mm I.D. x 12 mm width. This is a very common bearing used in many auto engine applications. It is widely available, but you get what you pay for. Find brand name, Japanese-made bearings like NTN, Naichi, etc. - all are high quality, OE equivalent. Expect to pay around $10 online for a high-quality replacement bearing for this pulley. Install the new bearing in the OE pulley.

NOTE: Be sure that the tensioner assembly spring is operating correctly before you repair/replace only the tensioner pulley. The tensioner must operate correctly so as to not put undue torque on the alternator and A/C pulley bearings.