Write-Up: Replacing Supercharger Belt Tensioner

I went to check on my GF's regal GS and it only has a torx on the lower s/c idler (pulley 9). I'm pretty sure that one is a t-50.

I would just get both, because for some odd reason, I remember doing the tensioner on my riv with a t-45.

gotcha. i'll look for a set of them. thanks all.

awesome, intense charged me twice..

Officially it's a T47. GM's gift to us, a torx bit that's not on the normal 5 scale.

Sears and most parts stores have them. Personally (haven't read entire thread yet) if this is the tensioner you are talking about, I would hit up a JY and grab the accessory tensioner bolt to swap the torx off there. Makes it much easier in the long run.

While reading old threads trying to educate myself about the Riv I have seen a couple of pics showing the wear indicator on the belt tensioner.
In this thread:
https://rivperformance.editboard.com/series-ii-engine-transmission-f4/should-i-upgrade-my-belts-what-about-pulleys-t36.htm
Page 2, post#2, third pic - the wear indicator is shown.

The one on my car appears to be worn exactly like the one in the pic.
How do you interpret the position of the lines on the plastic in relation to the notch on the aluminum housing?

Thanks

Bert

Either of the two small marks is where you want to be if I remember properly.

Would need to check the FSM though.

BillBoost37 wrote:

Either of the two small marks is where you want to be if I remember properly.

Would need to check the FSM though.

OK then, if thats correct I am all set.

Next on the agenda is to change the SC oil.

Bert

My stock SC tensioner didn't seem to move very freely, so I bought a Dayco tensioner from RockAuto, spec'd for the Riv. Thought I'd swap today, but it's not going so well. I've got the complete tensioner assy off the car, and I do NOT see how the F the tensioner can be removed from the bracket. It is not secured with a bolt, and appears to me that the entire assy would have to be replaced, bracket and all. Plus the Dayco tensioner places the pulley quite a bit farther out than the OEM tensioner does. The Dayco pulley location is physically farther away from the center of the tensioner than the OEM pulley on the OEM tensioner. Also the Dayco is set up to bolt to the bracket, and I see no provision for that on the OEM at all. The tensioner does not appear to be easily removable from the bracket.

At this point, I'm just going to clean everything up and reassemble with the old parts, and try lubing the OEM tensioner. I'd appreciate any input on this project. Not real happy the Dayco unit is so different. I'll have to compare part numbers, the tensioner on the car carries similar mfgr names on it, also made in Canada. Maybe RockAuto and Dayco don't have their facts straight.

do you have a pic of the part you bought? i pulled mine off to try and fix it a few months ago and the tensioner is all one sealed unit from what i can recall.

Yes, it looks like it's intended to be replaced as a complete assy, tensioner and bracket in one unit. However the service manual refers to tensioner removal, but gives zero details on doing it, and the diagrams/pics only show the accessories tensioner removal. I'll have to check it out on my AllData sub online. I don't have a pic of the new Dayco tensioner at the moment, but I'll try to get one tonight. I've got the old parts all put back together now, and the old tensioner doesn't feel at "sticky" as it did on the car, and the pulley bearing feels fine too, so I likely don't really need to replace anything currently.

New Dayco tensioner, part # 89367.

I suspect the OEM tensioner can be removed, but I wasn't going to any great lengths to do it, since the Dayco one doesn't appear to be correct, to me anyway.

doesnt look right to me either. you should be able to get the entire built assembly from gmpartsdirect or maybe even the local napa.

I'm sure I can, but it certainly appeared more practical to replace only the tensioner, since Dayco spec's this part as a correct replacement. I'll be checking with RockAuto on my return/refund options.

I've emailed RockAuto asking for a return authorization, but I'm about 2 months past purchase date. Supposedly a 30 day limit for refunds. But I've pointed out the apparent error in their catalog listing for this tensioner, and proposed to return it and re-order their AC Delco complete assembly for $73. NAPA has it for $109, GMPD is $90. GM list is $152.

Funny thing, in my 95-99 parts listing pages, it pictures the tensioner w/pulley only, not the complete assembly. And typing the part # in GMPD gives you a description of just "bracket". Anyway, I'm hoping RockAuto will see things my way and allow the return/exchange.

Today's update: Rock Auto is taking the tensioner back for a refund, admitting it does not appear correct. And I just heard back from Dayco directly, that they have it listed for the Rivs in error, but need to investigate to find how this came to be. They suggested I order a Gates 38351, which Rock Auto also sells for around $73, a bit more than the $50 tensioner that's no good. The 38351 I'm sure is the complete assy, tensioner/bracket/pulleys all in one. Not thrilled about buying it, I already replaced the idler pulley on my OE tensioner a while back, and the OE tensioner and pulley bearing are in better shape than I had thought. Think I'll just get my money back from RockAuto for now.

It was nice of RockAuto to refund you. I hear nothing but good stuff about these guys.

Dave, did your tensioner "chirp" at all to alert you it was bad?

I fully expected them to agree to a refund. They have this spec'd incorrectly for our Rivs, as does Dayco. It's only been 2 months since I ordered it, and I explained I had to wait for decent garage temps to begin work on it.

The only symptom that the OE tensioner may be going, was when I replaced that failed idler pulley in the winter. The tensioner did not seem to me to move quite as freely as it should. But when I had it off the car last weekend, I was able to move it thru its full range of motion without issue. So I'll leave it on, plus the smooth pulley's bearing felt perfectly fine as well.

Aaron, is it impossible to replace the LOWER sc idler pulley, without removing the eng mount? Appears that way to me. Mine is in horrible shape, the smooth plastic surface is deforming badly, looks MUCH worse than any other pulleys I've replaced on this car. I have a metal replacement for it already.

yea you have to take off the mount and bracket to replace that pulley. or at least i had to. PITA b/c you have no room to put the bolt in w/out jacking/lowering the engine. also i had a problem with the pulley rubbing the mount when i got it all back together, so i took it all back apart and re-did it. not my idea of a fun saturday. sorry i dont remmember any more details or what caused the pulley to touch the mount.

btw, my s/c tensioner still chirps when it gets warm. been doing it for almost a year now, so i'm not too worried about it.

Mine too. Chirp, chirp, chirp. But I wish it didn't.

Dave, I really don't know, because I had the dealership do the work when my pulley fragged. I think they under-quoted; it only cost about $75 out the door. They put a metal replacement on, too.

Dayco, naturally, says to replace a tensioner that is noisy.

So I'm finally getting around to ordering a SC tensioner from RockAuto. Looking at their catalog, I see several choices, including AC Delco #38351 for $74.79. Description says:

"TENSIONER,DRV BELT SUPERCHARGER; 2 DOORS; BELT DRV TENSIONER"

Is this the one I want to order?

Yep, that should be the one. I have that number written down in my notes, but at $64.79. Must have gone up.

They offer several alternatives, priced from $59-$94, but I think that's the only one for the SC belt.

I have a discount, so it's worth it to stop the squeak. I'm 85% sure the worn out tensioner is to blame for the noise.

5%?