Tremo

Gents, the serp belt tensioner in my 88 LB9 IROC is making noise, time to replace, it is the factory original. I can get a GM Delco replacement, OEM style from RockAuto. I see it mounts to the bracket with a single bolt which is recessed in the spring assembly. Question is, what size socket fits it? Anything special I should know before starting to wrench? Thanks!

WildCard600

Are you replacing the whole tensioner, or just the pulley ? I put a new pulley on mine yesterday, 13mm socket is what I used.

DaveyDug

iTrader: (3)

I was getting some clatter at idle from mine so I replaced it with the GM/AC Delco part a couple months ago.

For some reason the new parts have a 3/8" drive square hole for the spring tension release instead of the factory 1/2" drive. Kind of annoying, but the tensioner looks and functions great otherwise, and my noise is gone.

DaveyDug

iTrader: (3)

Oh, and to answer your question OP, you need a T55 torx socket to remove the bolt.

Drew

iTrader: (58)

You can get the bearing for a few bucks and press the old one out and new one in, if you want to preserve the original look and save a buck. I want to say it's the same bearing as a Ferd alternator nearing, making it very easy to find.

sofakingdom

iTrader: (1)

What Drew said. Although it's also for many GM alternators.

6201 bearing, seals both sides. Different mfrs use different prefixes or suffixes in addition to 6201 but that's always the core of the part number.

edit: should be 6203, not 6201

Tremo

I don't have a press or access to one. I can get an exact GM Delco replacement from Rock Auto so the original appearance is maintained. I will be replacing the whole thing, pulley plus the spring loaded mount.

So is it a T55 Torx or a 3/8 inch square drive to get the old one off the motor? Thanks.

DaveyDug

iTrader: (3)

1/2" square drive to remove spring tension so you can slip the belt off, then T55 to remove the tensioner assembly from the car. The new one will reuse the T55 torx bolt, but will use a 3/8" square drive instead of the 1/2" drive to pivot the tensioner and allow the belt to be reinstalled. This is where the new GM parts differ from the originals and this is what Drew was referring to by "preserving the original look". The new tensioner will look slightly different from the one you took off in that the square drive is a different size.

Tremo

Thank you for the explanation. Now I understand why the photos of the parts on RockAuto look a little different, that square hole did look a bit smaller. I have both 1/2 and 3/8 drives so no problem there. I even think I have a T55. Is the T55 the same one used to replace the gas struts which hold up the rear hatch? I just did that so if that is the same one, I have it.

Thanks!

DaveyDug

iTrader: (3)

I think the hatch struts use a T50, but I'm not 100% sure.

Drew

iTrader: (58)

Rock Auto sells two different AC Delco tensioners, the $70 one is close, but not 100% correct to the original. The other uses a smooth pulley. Hence why a true authenticity junky with penny pinching proclivities will go with a sub-ten-dollar replacement bearing, they can get TODAY and change in a matter of minutes.

I don't own a press either, but I can remove and replace most pressed in bearings and bushings. I won't go into specifics, but between a heat gun (Big F Hairdryer) and a Bernzomatic propane torch and careful application of all thread, mallet/hammer, and various spacers, there's not much work I hire out. Granted there's a learning curve involve, but you know if I melt a 5.0 Ford distributor now and then, it's not a huge price to pay when the skill developed saves $60 on a tensioner here, $40 on an alternator there, or an $80 shop labor fee here or there... I'm sure at this point I've saved enough replacing my own bearings that I could go buy a HF 20-ton press and still come out ahead. Food for thought.

Rock Auto is awesome, be sure to use a 5% off coupon. https://www.thirdgen.org/forums/afte...t-codes-3.html

Tremo

You can replace just the pulley only? I was told to replace the whole damn thing. On mine, the spring part is still working just fine. I really just need a new pulley/bearing.

WildCard600

Yes. Relieve the tension on the belt to get it out of the way and it's one 13mm bolt IIRC. Slide the new pulley on and tighten bolt, put belt back. Took all of a minute.

I bought a new pulley at the local auto parts store, but rock auto has them cheaper assuming you are not just shipping the one item. Will not "look original" though.

I would have just done the bearing but didn't want to mess around with it at the moment. Keeping the original pulley to put a bearing in later for a backup.

DaveyDug

iTrader: (3)

Yeah, the replacement pulleys are smooth, unlike the originals.

Tremo

Well, damn, got a bit of a surprise last night. the reason I have been inquiring about this is when I first start her up, there is some funny scraping noise that I can hear, but it goes away after a couple miles. So last night, just out of curiosity, I grabbed my 1/2" drive and popped the serp belt off the tensioner so I could rotate the pulley by hand and feel/hear what it is doing. There is no problem, It rotates smoothly and freely, makes no noise and there is no wobble or looseness. It appears to be fine! And it is the original on the car with 175k on the clock.

So then I started hand turning everything else. Alternator is fine, smooth, no sloppiness or wobble. Ditto the steering pump, water pump and A/C compressor. The smog air pump is not so smooth. There is no looseness or wobble but it does not rotate smoothly. Hummmmm........

DaveyDug

iTrader: (3)

Ok...

Let me preface this by saying that I am NOT telling you your tensioner is bad and your smog pump is good.

BUT... here are my observations:

In my experience, the smog pump has a little bit of resistance when spinning the pulley by hand. It does not rotate as freely as, say, your alternator pulley will. AND, when I spun my bad tensioner pulley by hand it seemed to rotate freely and made no excessive noise at all. But after I put the new tensioner on, my clacking at idle was gone. YMMV.

WildCard600

^^ This.

I had the same experience.

GeneralDisorder

iTrader: (1)

You can replace the bearing in the pulley with a couple sockets.....no press required. Or buy the whole pulley. Typically no need to replace the tensioner assembly itself.

GD

Tremo

OK, the pulley is cheap. I'll go ahead and replace it with the Delco unit from Rockauto.

Tremo

Ok. I bought the Delco brand replacement tensioner pulley from Rockauto. It is slightly smaller in diameter than the original. I put it on tonight and it took about 5 minutes. It looks ok. You guys know of any issues caused by these replacements being slightly smaller?

WildCard600

Is the part the belt rides on actually smaller or does it just appear smaller because it dosent have the raised edges like the original ?

Tremo

good question. I held them side by side and with the lips the original is bigger. I think the actual flats may be the same because the position marks on the spring arm are right in the middle of where they should be.

Tremo

I see the 6201 sealed bearings on eBay for cheap. I have a friend with a machine shop he can probably press it into the original pulley. Which bearing brand is better?

GeneralDisorder

iTrader: (1)

You don't need a machine shop to press a 6201

You just need a couple sockets. One larger than the bearing to support the pulley, and one the size that will knock it out of the pulley. You set the pulley on the receiving socket and knock out the bearing with a hammer. It's SUPER EASY. You can change that bearing in about 3 minutes with some stone knives and bear skins. You certainly don't need a machine shop. Good lord. Your friend will think you have lost your mind.

As for bearings - NSK, NTN, Koyo, or SKF are generally excellent choices. You want a 6201-2RS-C3 bearing for this application. Most large cities will have bearing supply houses that will have about 1000 of these in a drawer for about $5.

Also any good auto parts store can order one - it will be labeled as an alternator or commutator bearing, or a clutch throw out bearing. It's a jelly bean part - they are all the same. Look up both 6201 and just "201" (the 6 is implied because it's a "6000 series") standard radial ball bearing. A 7201 would be a "7000 series axial thrust bearing".... etc. This is just a standard off the shelf bearing used in literally MILLIONS of applications from electric motor bearings to industrial conveyor systems....

GD

Tremo

Well the new pulley fixed the funny noise I was hearing on startup. Noise gone. It was the old pulley.

Popped on a new Gates SERP belt as well, the old one was pretty stretched.

Now to go back under and change the fuel filter. Got my flare wrench.

Tremo

man I’m not a wrench head. I’m a sales manager in the day job. I do simple wrenching on the IROC for fun. I have limited tools. The guy at the machine shop owes me a favor.

Drew

iTrader: (58)

Jump on the Youtube and look for videos on replacing bearings. On small stuff you can usually apply a little heat to expand the bearing race or the socket the race fits into, then you can just slide the bearing in or out. Thick leather gloves will protect the paws.

GeneralDisorder

iTrader: (1)

So save the favor for when you need a wheel bearing pressed.

You telling me you can't find two round things and a hammer? Seriously? C'mon use that brain. It's about problem solving and being satisfied with a job well done. It's about accomplishment. If it wasn't you could just pay a shop a couple bucks to fix the whole problem.

GD

LiquidBlue

Just noticed this thread. Anyone happen to know why the new pullys are available in smooth, rather than having a lip like factory?

Drew

iTrader: (58)

Magic V8-ball say - "smooth pulleys are universal, cheaper to use a pulley that covers a lot more applications"

GeneralDisorder

iTrader: (1)

Also - the belts don't fly off the smooth pulley so it would seem that the lip was redundant anyway and likely over-engineered.

GD

LiquidBlue

hmmm, maybe better performance and gas mileage while less wear on belt

Drew

iTrader: (58)

Fat chance of that. It's not an engineered improvement or GM design improvement. It's literally that Dayco and Gates can make one pulley that fits X number of applications, so they don't have to make a pulley specifically for thirdgens. For it to be any kind of improvement like you're thinking, the lips (guides) would actually be keeping the belt on the pulley. But no, it has everything to do with having the bare minimum of parts on the shelf to service as many applications as possible, so they can save money and make more money. Just like it's easier to use a smog delete pulley for a truck and route the belt on the opposite side of the pulley so you can use a smooth pulley that's shared with other applications VS using the correct molded/ribbed pulley. Follow the $$$. They aren't redesigning tensioner pulleys for 30 year old cars to help save you a buck by not selling you a belt.

TF34MECHH

I ordered 6201-2RS-C3 bearing and it is too small. I removed my old stock pulley and the bearing has 6203 listed.
6201 has an OD of 32mm and ID of 12mm. 6203 is listed as having an OD of 40mm and an ID of 17mm.
Can anyone confirm if the stock bearing replacement should be an 6203?
Thanks

GeneralDisorder

iTrader: (1)

If it says 6203 on then yeah order that. 6201 was based on Tremo's observation of his pulley. It is possible they don't all use the same one.

GD

TF34MECHH

Ok thank you for the reply and the help. I should have double checked mine before ordering. It's still worth ordering since I want to keep the original pulley with the raised edges.

sofakingdom

iTrader: (1)

Sorry, You're right: 6203, not 6201. My bad. A senior moment I guess.

17mm shaft x 40mm bore x 12mm thick

6201 is indeed quite a bit smaller.