Hi: We're on a trip out of town, away from our usual parts and repair facilities. 1999 RX300 w/ 270K miles. Battery light started intermittently being on, now is continuous. Indicates a problem in the charging system. Belt seems fine. Terminals on the battery are tight. Any other suggestions other than the obvious - replace the alternator? Called a local parts store; their parts catalog shows two different versions, difference being pulley diameter, one something like 55 mm, the other 65 mm. No explanation for why two different ones. Any insight? I don't have access to the tools with which to replace the alternator myself, so at the mercy of a local repair facility. Are the pulley's likely interchangeable in case I get the wrong one? The store only has one of the two versions in stock, and I need to get back on the road on Monday. Help!

 

There was a 57mm pulley and a 65mm pulley depending on your year and options of RX. Standard alternator rating is 100 amps, but starting in 2001 there was an option for the 130 amp alternator with the towing package. I assume the high output one had the smaller 57mm pulley to spin that more powerful alternator. I couldn’t decipher online which alternator had the larger or smaller pulley, but apparently early 300s had the 65mm and the later production ones had the 57mm (most likely these ones mainly came with the 130 amp) according to this post.

https://www.clublexus.com/forums/rx-...size-help.html

I would measure the pulley and see how large it is just in case. If the store can’t explain why there is a difference between the two or what year ranges they fit, I’d try calling another store if possible.

 

The pulley size impacts the rpm of the alternator and belt size. If you are dependent on the mechanic, let him get the right part.
Or just measure what you have.

Salim

 

Using RockAuto as a source for 1999 RX300 parts.

DENSO2101029 {#1012117840, 2100445, 2706020110} says "to 07/1998"
DENSO2100439 {#1022110590, 2706020140} says "from 07/1998"

The above doesn't say the pulley diameter but
REMY 12095 {Click Info Button for Alternate/OEM Part Numbers} Premium Remanufactured Info
w/ 65mm Pulley; 120 Amps
says Alternate/OEM Part Number(s): 1012117840, 13844, 2706020110, 9661219784

REMY 12226 {Click Info Button for Alternate/OEM Part Numbers} Premium Remanufactured Info
w/ 58mm Pulley; 100 Amps
says Alternate/OEM Part Number(s): 1012117440, 1012117450, 1022110590, 1022110840, 12369, 12373, 12374, 13844, 270600A070, 2706020140, 2706020200, 2706020230

So if the above is all accurate, the 65mm pulley was used on cars manufactured before 07/1998
As for the belt, all the ones I checked that quoted a length were the same length.

The one I most recently installed in my 1999 RX300 is 58mm pulley:
https://shop.advanceautoparts.com/p/...56a/19850518-P

 

Thanks guys. Unfortunately I do not have the luxury of canvassing multiple sources, e.g. RockAuto, due to location and urgency to get back on the road. Will advise how this plays out.

 

Two questions though remain: Is the pulley diameter measured externally, or internally, i.e., where the ribbed belt rides. And, are the pulleys interchangeable?

 

10 mm difference is large enough that you can use a ruler. Being purist, I would say it should be the place where the belt runs.
Give Lexus parts a call and give them your vin an they should tell you the size, Call now or call a west cost dealer.

Salim

 

X2^^^^^ Like said above, if your not doing the work, Really best for the shop to get the correct alternator for your vehicle, as well as the shop will warranty the labor as well as the part if it goes bad....

 

Alternator
Here is what I did to my 2002 RX300 ! Beginning of 2017, decided not to take a change and drive long distance on a 15 year old Alternator. I went on eBay and bought an alternator for $100.00 !! Replaced it when travelling to Vero Beach, FL in the hotel parking lot. I had all the wrenches and socket ones to do the job !! It took me about an hour to perform the job. Go to You Tube to see a video on how to do it and what tools are needed. Good Luck, EJ Dossary, EE

 

One of the reason I had no issues with the bearings was that I use belt tension measuring tool. When you use a new belt [less than 10 mins on the engine] there is a substantially different tension. I never relied on the twist test [used to be some what OK with V belts].Now all my vehicles have a tensioner and the tension gauge now sits in my tool box.

Salim

 

Mission accomplished. The only locally available alternator was a proper replacement for the original one in my 99 RX. 65 mm diameter pulley I believe. Back on the road later in the day and got home 150 miles later without incident.

 

Replaced my alternator using Denso remanufactured that can be purchased from NAPA. A little on the pricier side but the closest you can get for an OEM replacement without breaking the bank. Looks brand new.

Part Number: DEN2101028

Original is a 65mm pulley. Replacement is a 58mm (or 57mm?). Works just the same using the same belt. It produces >14v compared to the original at the low 13v.

 

You must have bought the last one! Out of stock in stores, not available for shipping.
I prefer the 58mm pulley, it is easier to install

 

You can have your store shipped the item from other stores. It may take a while but possible. Several other stores have it in stock.