MrLeadFoot

Try as I might, every search I could think of came up with results for the a/c belt pulleys, which I already previously replaced. Does anyone have the GM part numbers for the main drive belt idler and tensioner pulleys? I know for the a/c belt, the idler and tensioner pulleys are the same, but I think the main/accessory drive belt idler pulley is different than the pulley on the tensioner, right?

helga203

I just went throught this. Go to rockauto, go to make and model, then what year. Go to belt tensioners. They have all the different pulleys you need. A/C delco is the ones i bought. Already installed with no problem. Everything lined up perfect. When you read description it states main drive or a/c drive.

MrLeadFoot

Thanks for the suggestion, but Rock Auto shows multiple AC Delco pulleys for both main drive idler and tensioner pulleys. Now what?

helga203

Get the professional one. Ill get you the #'s

MrLeadFoot

Rock Auto descriptions are not clear, and apparently not even right, sometimes confusing main/acessory drive pulleys with a/c system pulleys, yikes!. I cross referenced them with parts on Amazon to narrow down my options. I then read the reviews on Amazon, which weeded down the list to these two:

AC Delco 38008 for the tensioner pulley, although it is listed as "flanged idler pulley" on Amazon
AC Delco 12564401 for the main drive belt idler pulley

Does anyone think these are wrong? Even though Rock Auto is slightly cheaper, I'm leaning towards Amazon because:

1) They weren't as confusing,
2) When I factor in Rock Auto shipping vs. two-day free Amazon Prime shipping, it's pretty much a wash
3) Rock Auto once sent me a wrong fuel pump, even though I ordered the right one, and they refused to rush me the correct one, even when I explained that my huge Suburban fuel tank would now have to lay dangerously in my driveway for a week. I'm sure you can imagine what I told them when they said there was nothing they could do about their mistake, whereas on the rare occasion when something has gone wrong on Amzon, they've been stellar with customer service, even if it was my fault.

Sorry, I digress. Any additional thoughts on the parts I am thinking are correct?

helga203

here are the one's i would order. ACDELCO Main Idler 36225, ACDELCO Tensioner pulley 1540486. These are not a/c pulleys. Their the main drive. I just bought the whole tensioner with pulley.Just to make sure it is new tension.

MrLeadFoot

Interestingly, gmparts direct also says the idler is the number i posted above, not the number you posted. Are you sure 36225 is what you used? In fact, 36225 is not even listed for my car on Rock Auto.

helga203

Yes, It's the same pulley. All the dimensions are the same.ACDELCO 12564401 same as 36225.

MrLeadFoot

I don't even see a 36225, which is why I questioned the numbers you originally posted, and forgive me for saying so, but I still don't, so I obviously don't see specs on the 3225. In either case, the 12564401 is one of the numbers I originally asked about.

The 1540486 comes up with conflicting applications when I search for that tensioner pulley. To that end, searches for the 38008 tensioner pulley result in the correct fit. You went for the complete tensioner and not the 1540486, correct?

I don't know why Rock Auto displays multiple AC Delco pulley numbers with different prices for the same application. I don't think I should trust their numbers.

To make matters worse, Summit Racing shows yet another different alternate part number for the idler pulley!

helga203

yes It is confusing but even the dayco pulleys have the same to close deminions. Try GMparts. The pulley that I got the deminions where off a little but is perfect. Belt rides in the middle of the pulley and there steel now not plastic.

NOS2006

Hey guys! Sorry, not trying to bump an old thread, just trying to understand if the Main Drive and Accessory Drive share the same Idler Pulley (AC Delco # 12564401).

Thanks!

MrLeadFoot

No, they do not.

NOS2006

Do you know the other P/N then?

MrLeadFoot

I bought mine off Amazon, but unfortunately they only store past orders for so long so the order doesn't show. But, if I remember correctly, one is flanged, while the other is smooth. Also, I found conflicting part numbers at all the places like Autozone, Napa, O'Reilly, etc. I even bought them local only to find they didn't fit. In the end I went AC Delco off Amazon, and they were a perfect fit.

MrLeadFoot

Oops, my bad. I was thinking tensioner vs. Idler. Sorry about that. Idler s are both smooth, but I don't remember if they're the same between belts.

KennyP55

hey guys... new owner of a 2004 Z06 with 51k miles which is my first vette an I am absolutely loving this car!.

I had to replace the harmonic balancer and had a new stock size Powerbond balancer installed which is excellent. i noticed that the main serpentine belt continues to slip off the belt tensioner after hard driving which it also did with the old balancer and I thought this new powerbond install would have corrected.

The belt never comes off that passenger side tensioner completely, but 1-2 ribs slip off and I get my wrench out to pull down the tensioner and slide the belt back on.

My tensioner only moves maybe a quarter of an inch when I use the wrench to push it down so I am concerned that either the belt is too small and not allowing the tensioner to extend fully, OR my tensioner spring is just shot at 51k miles and time to replace????

Here's a photo of the belt tensioner (passenger side) and you can see where the metal tab on the right aligns with the 3 "lines" on the left which on mine is the middle of the top line. I've searched the boards here and cant find an answer to where these tensioner wear marks/lines should align if the tensioner is working properly? I assume since I can barely push down the tensioner to release it that either I have a too small belt, OR the tensioner spring is shot? any ideas? thx guys



2004 c5 Z06 belt tensioner with 51k miles.