Write-Up: Replacing Supercharger Belt Tensioner

Can you jam a large flat blade screwdriver in and get any leverage?

Could try drilling a large hole, then thread a bolt (normal thread dir) and loosen with a wrench. If you have a welder around, can weld a piece of steel bar or a nut to it and then break loose.

GOOD suggestions, AA.

Yes, some drilling or welding will be required. Weld a nut to the bolt head so you can put some leverage on it.

Thanks for all the suggestions. I wish I did have a welder (I really need to buy one and learn how)that would have been the way to go. I don't have a right angle drill so I wasn't able to get a drill in there.I ended up jamming a flathead screwdriver in there (thank you Dave) and was able to get some leverage with some vice grips. Somehow managed to get the belt back on (thank you god i will stop drinking so much like I promised). So for now I will leave it the way it is. Just hope I don't have to change pulleys soon.
cheers...beer time...oops i already forgot.

For many months, I had an annoying 'chirp-chirp-chirp' sound at idle during certain days, usually at start-up, and especially on cold, damp mornings. I thought it was an idler pulley or tensioner pulley, so replaced both with no luck. A clue came when I used a small ratchet to slightly de-tension the supercharger tensioner unit with engine running (if you try this, be extremely careful!). The result was the chirp went away.

I ordered Gates supercharger tensioner # 38351 from Rockauto.com for $57.79; total shipped was $65.32. Below is a write-up showing the installation, which is not very difficult, uses a few basic tools, and should take roughly 2 hours the first time. In a hurry, I think it could be done in 1 hour.

After installing the fresh tensioner unit, the chirp sound went away and so far hasn't returned after more than 3 months. Best of luck with your installation!

STEP 1: Using a ratchet and T-50 Torx bit, de-tension the supercharger belt by applying counter clockwise torque to the supercharger tensioner pulley bolt. The tensioner bolt is reverse (left hand) thread, so counter clockwise torque will cause the bolt to tighten, and the tensioner to move, loosening tension on the belt. Remove the belt from the supercharger, idler, and tensioner pulleys and tie/prop it out of the work area. There is no need to remove the belt entirely from the engine (trust me, you don't want to anyway).



STEP 2: Use the T-50 Torx to loosen the supercharger tensioner pulley using clockwise (reversed) torque, accessing the 15 mm nut behind it.



Remove the three fasteners (normal right hand thread) securing supercharger tensioner unit, and SC tensioner pulley. The top one is a 13 mm bolt, the lower is a 15 mm nut, and as mentioned there is one 15 mm nut behind the SC tensioner pulley. Remove the pulley and the nut. Do not remove the studs.







STEP 3: There is a ground connector attached to one of the studs. Disconnect it and remove the remaining 15 mm nut behind it.



STEP 4: The coil packs are fastened to a bracket that mounts to the supercharger tensioner unit. There are two 13 mm bolts holding it on - one of them you have previously removed in STEP 2. The other is bolt is located to the left side of the coil packs, as seen when looking at the engine from passenger side. Remove this bolt with a 13 mm short-well socket wrench.



The coil pack only needs to move enough to remove the supercharger tensioner unit from behind it. You may leave the ignition wires connected.

STEP 5: With the coil packs free, the supercharger tensioner will easily slide out from behind it. Remove the supercharger tensioner unit. GM part # is 24506376.



STEP 6: See pictures of old and new supercharger tensioner units below. If you ordered Gates item # 38351, it comes with Chinese-made idler and tensioner pulleys to save costs. You may want to replace them with better quality pulleys, or different diameters if you have a modified blower drive set-up. If so, wait to install these pulleys in STEP 9.











STEP 7: Install new supercharger tensioner unit and reinstall coil pack bracket. Install 15 mm nut and 13 mm bolts hand tight (remember one is on left side of coil pack). Use T-50 bit to remove new supercharger tensioner pulley - it loosens clockwise. With tensioner pulley removed, install the last 15 mm nut.



STEP 8: Tighten all 13 mm bolts and 15 mm nuts to 25 lb-ft. Install ground wire connector and 15 mm nut. Tighten it to 25 lb-ft.



STEP 9: If you want to replace the new idler/tensioner pulleys with those of different size or better quality, you may do so now. Otherwise, reinstall the new tensioner pulley. Tighten pulleys counter clockwise (reverse thread). Tighten tensioner pulley counter clockwise until tensioner arm starts to move. Do not over-tighten!



STEP 10: Route supercharger belt along correct path and de-tension the new tensioner arm. Slip the supercharger belt onto the tensioner pulley and release. The belt should now be installed and tight. Inspect belt routing and start the engine to confirm proper operation.



IMPORTANT NOTE: Any time you release tension to the supercharger belt, care should be taken to be sure the belt has not become misaligned with the crank pulley grooves when tension is reapplied. The crank pulley is the large one at the bottom of the engine. Both serpentine belts are driven by this pulley. From below the car, you can check for correct orientation of the supercharger belt on the crank pulley.



If you do not check this, and the SC belt is installed incorrectly, you will experience premature belt failure within a few thousand miles. It begins with a faint white line seen on the outside edge of the belt's flat side, followed by separation of the outside belt rib. This can damage underhood components, insulation, cooling hoses, or the other (accessory) belt. After installing the new tensioner, check your supercharger belt for abnormal wear after 500 miles.

Good luck and happy wrenching!

So.... yeah.. the belt tensioner pulley is a little off from the SC coupler and feeding it a little crooked causing belt squeal whenever I cold start the car... I've sprayed a crapton of belt dressing and that makes it atop until thenext morning....

So is there any way to preposition the tensioned... or even have a spacer for it? Do they sell slavers? Would washers work Or is that a bad idea?

Thanks

You shouldn't need anything like that. Is it possible the belt is on crooked. Take a good look at the belt where it goes around the balancer. If the belt isn't positioned correctly there, it will ride crooked the rest of the way. If not, the tensioner itself may be at fault.

The tensioner is cast so that when everything is OK the pulley(s) will all be in line. Most likely the bearing in the tensioner pulley is failing. Hint - see if you can smack the pulley back into alignment with the heel of your hand or a rubber mallet.

Best thing to do is replace the pulley that's out of line (before it seizes and causes you real headaches), they are not that expensive even from a GM dealer. And since they are widely used they are also widely available. Just be sure you get the correct side (it's not hard) and be aware that some are on reverse threaded bolts (the thread of the bolt is always such that the belt travel would tend to tighten that bolt).



Albertj

Cool.. thanks... yeah the thing is that the engine is from a gtp and the tensioner also I suppose... the Guy doing the swap with me did the belt setup and said that he had to kindof mix and match the belts and maybe pulleys... and the belt on the tensioner pulley is kindof looking like it wants to slide off... and when I fix it and start the car up it goes right back... its frustrating... and when I look at the setup everything is in line except the tensioner pulley which looks slightly angled downward.. even when I tighten it.. it also looks like its not only angled downward some but should stick out another 1/4" further....? That's why I think a spacer would fix it...

wee-one wrote:

Cool.. thanks... yeah the thing is that the engine is from a gtp and the tensioner also I suppose... the Guy doing the swap with me did the belt setup and said that he had to kindof mix and match the belts and maybe pulleys... and the belt on the tensioner pulley is kindof looking like it wants to slide off... and when I fix it and start the car up it goes right back... its frustrating... and when I look at the setup everything is in line except the tensioner pulley which looks slightly angled downward.. even when I tighten it.. it also looks like its not only angled downward some but should stick out another 1/4" further....? That's why I think a spacer would fix it...

If you look in for instance the Rock Auto catalog you will see that it's the same tensioner on the 96-99 Riv as on the 97-98 GTP...

So the mix/match of belts is not a cause of the problem, really, assuming that of the belts and tensioners that were in the garage when you did the engine swap, the best available ones were mounted on the engine.

Given that... Best thing to do is replace the pulley that's out of line (before it seizes and causes you real headaches), they are not that expensive even from a GM dealer. And since they are widely used they are also widely available. Just be sure you get the correct side (it's not hard) and be aware that some are on reverse threaded bolts (the thread of the bolt is always such that the belt travel would tend to tighten that bolt).

Hey guys. I have another question. My supercharger tensioner is too wide in diameter causing it rub against the mount. It's not a pleasant sound. I need a smaller pulley so this doesn't happen, any suggestions. I also put a new gates tensioner on today.

Thanks and Happy Holidays.

What else did you change to cause this interference? The new tensioner should align the pulley the same as before. Have you got the belt on correctly?

Nothing different but I will upload pictures of what it looks like. How do you upload pictures on here?

^^^^ Click above:

sorry about the quality, from my phone.

Is the outer corner of the pulley rubbing on the front engine mount bracket?

Looks like you have the wrong diameter pulley there. The diameter of that tensioner pulley should be the same as the other SC idler pulley. Someone may have put a larger tensioner pulley there to compensate for using a smaller supercharger pulley without having to change the belt.

it does rub. this pulley came with the tensioner. my tensioner set up does not look like the one in the write up. what's up with that?

deekster_caddy wrote:

Is the outer corner of the pulley rubbing on the front engine mount bracket?

Looks like you have the wrong diameter pulley there. The diameter of that tensioner pulley should be the same as the other SC idler pulley. Someone may have put a larger tensioner pulley there to compensate for using a smaller supercharger pulley without having to change the belt.

Good eye. Can you use your old pulley until you get a replacement?

Unfortunately both pulleys are the same size. Is it possible that the engine has dropped? The reason why I say that is because I had to slightly jack the engine up to. Remove the tensioner.

my guess is you have at least one dead motor or transmission mount, or even both

Alright you guys. I just wanted to update you guys on the status on my riviera. Some of you guys know that I was having an issue of the supercharger grinding on the passenger motor mount. Well recently I took it in to the auto shop where I was told that all three bolts on the engine block broke causing the engine to fall. The three bolts were repaired and replaced along with both belts. When I started the engine yesterday it was quiet as it was back in '97. The start-up was quiet as a whistle and nothing and I mean nothing squeaked or shuck. I drove it and it was a smooth ride with so much power under the hood. With all the repairs and tweaking it cost around 500 dollars.

Thanks for the update. These were the bolts holding the passenger side mount to the engine?

Yep

albertj wrote:

my guess is you have at least one dead motor or transmission mount, or even both

congrats on finding the problem. Hope my guess helped.

Albertj