Hi all,

SC2 has been chugging along. Died on me once, that was a bad ignition module. New module + plugs and coils for good measure, and it's been faithfully taking me wherever I want to go.
Now the other day, the belt broke. This surprised me, since I thought that was fairly new. No bother, I got another belt, put it on, and drove home. Today, I decided to take a closer look, since something about the tensioner seemed a little funny when I was changing the belt. The new belt has a line worn into the back, which looks a lot like how the old belt was split. Also, now I see the tensioner is out of alignment with everything else. I released the tension and tried to move the pulley, it didn't feel loose, seemed to spin ok. OK, so new tensioner time. Here's where I run into a problem.
Looking on rockauto, I see some have a note of 90mm (roughly 3.5 inches). All others appear to be 90mm as well. I measure mine, it's more like 3 inches. There are a few tensioner pulleys listed as 76mm (2.94 in). So that sounds like what I need. But, I want the entire assembly, since I can't tell exactly where the problem is.
So-
Is this something known with these engines? Can the 90mm replace the 76mm? (seems like it would be awfully tight, if it works at all)
Is the 76mm some unusual configuration, so is now unavailable? In that case, do I buy the 90mm assembly and 76mm pulley and swap it over?

I checked a bunch of different years, single cam, dual cam- looks like the same list no matter what. I even checked Amazon (shudder)- all of those look like 90mm also.

 

I wonder what year your SC2 is ....

 

Working on it........ Had you previously replaced the belt tensioner fullf assembly or just the belt tensioner pulley?

 

It is common on Fords for the tensioners to be 76mm and the idlers to be 90mm. I can look at my 94 GM in an hour or so, it is still dark outside.
According to Napa all Saturn S from 91-2002 take the same tensioner with the 90mm maybe pulley. They sell a 90mm idler. The pulley on the tensioner does not give the size.

 

The 76 mm pulley is actually the correct original specification for the 1991–2002 Saturn S-Series for the SOHC and DOHC 1.9L engines. While many parts listings will tell you the 90 mm is "compatible," on the Saturn 1.9L S-Series, using a 90 mm pulley often causes the tensioner arm to sit at the wrong angle and also ***** it non-parallel to the engine block..
Because it is larger in diameter, it pushes the belt further out and can also cause the tensioner to "bottom out" or cause the belt to ride unevenly on the water pump or alternator pulleys. So a 90 mm is technically compatible but may cause issues as noted above.

If you are having alignment issues with the 76 mm belt tensioner pulley still installed in the vehicle, it may be that the aluminum housing where the tensioner bolts to the front cover of the engine is worn, causing the entire 76mm pulleyed tensioner to **** at an angle.

A Gates 38006 is a compatible 76 mm pulley for the belt tensioner. So is a Litens 900020A which supposedly is the OEM part. Both are currently available at RockAuto, but note that they are only the pulleys.

It sounds like you need to address the aluminum mounting spot being worn. The aluminum is already messed, so do not just stick a bigger bolt in there or try to shim it with anything. You need to restore the structural integrity where the aluminum bracket bolts to the timing cover to ultimately get this to line up again.

The safest way to embark on that journey is to remove the timing cover and do the work on it while it is off the engine. Look up the procedure for doing so, noting that there are several bolts that go through the oil pan into the timing cover. If you don't remove these and pull on the timing cover, it will bend and likely never seal properly again. It is doubtful you will find another to replace it as the yards have been scavenged for just this reason.

This is where my expertise comes to an end. Actually it did a while ago. Apparently you need a full stainless steel insert centered around the center of the hole in the timing cover.

The following is a blurb I pasted in from AI. I take no responsibility for its correctness. Andy, could you please chime in as to whether the following is appropriate? Or if you have, from your experience, handled this differently during your career? Much appreciated.

------------

The Repair Strategy: Threaded Insert (Time-Sert)

​For an egged-out aluminum hole, a simple Heli-Coil is often insufficient because it does not provide enough material thickness to restore a perfectly round, load-bearing surface. You need a solid, thin-walled threaded insert (such as a Time-Sert or Keensert).

Recommended Steps:

1. ​Re-establish Alignment: You must ensure the hole is drilled perfectly perpendicular to the mounting surface. If the hole is already oval, you cannot use a standard drill bit by hand, as it will just follow the "egged" path. Use a drill guide or a piloted counterbore to cut a perfectly round, larger hole that centers on the original axis.
2. ​Over-size the Hole: You will need to drill out the wallowed hole to the specific diameter required by the oversized insert.
3. ​Install the Solid Insert: Use a permanent, high-strength thread-locking compound (like Loctite 271 or 272) when installing the insert. The insert will provide a steel-on-steel interface for your tensioner bolt, which is much more durable than the original soft aluminum.

---------+--

If the mounting hole is the issue, you may not even need to replace the pulley if the bearing is still good. But it has probably been wearing unevenly if it has been off angle for quite some time so it's probably better and safer to just replace the belt tensioner pulley while doing all this.

That's all I got.

Andy?

 

Wow, you guys are on top of it, thanks for the quick response! It's a 2002 btw. Until now, I have not changed anything on the belt drive. I'm only on year 2 with this car, I'll have to look through PO's receipts to get an idea if anything was done before. Fortunately he left me with a lot of them.

Also wow, this is suddenly potentially a much bigger issue than I expected. Hopefully the weather holds out over the weekend so I can examine this further.

 

The other thing I was thinking of (before this whole mounting bolt/surface thing) with the 90mm was maybe find a slightly longer belt to go with it- stock is 780K5, maybe 785K5 or even 790.

 

I revised my post #4.

 

Apparently, some people who experience problems using the 90 mm replacement actually found that a 100 mm or placement for the pulley on the belt tensioner is sufficient to keep the tensioner in such a position that it does not bottom out. Has to do with the belt routing differently physically in space. At least that's what I tell myself.

There are other belt tensioner posts on this forum, but I can't remember this particular issue being posted. I had to do quite a bit of digging to figure out how you could have a 76 mm pulley on the belt tensioner. Basically, GM didn't want to make the 76 after Saturn went bye-bye so, per Andy, they just spec a universal GM 90 mm.

But the issue of the hole being distorted, I truly don't remember that ever being posted here.

Ultimately, you can certainly try a 90 mm pulley that comes with the spring loaded belt tensioner unit and see how that works. If it doesn't work out you can swap out the 90 mm for a 76 mm. But you have to determine if the mounting is the issue for it being out of position with respect to the rest of the pulleys.

How many miles are on this car?
How's the compression/have you tested it?

Remember, there may be more elegant / less labor intensive ways to address the mounting situation. What I pasted above is an example.

 

Took some pictures today, which gave me an even closer look. This one pretty much tells the story. Sorry for being so huge, but it's necessary for detail.

First, you can see how the pulley is offset from everything else.
Second, you can see the wear pattern on the backside of the belt, caused by the tensioner pulley sticking out, causing ~1/3 of the belt to be hanging off the inside edge.
Third, I only saw this when getting this picture, the spring does not appear to be touching the housing. How it's maintaining tension if that is the case, I have no idea. So I think it's pretty safe to say the tensioner is shot.
I looked to see if the assembly seemed like it was cocked in there, it doesn't appear to be, so that's good.

It's got around 207,000 mi on the clock. I did do a compression test, and initially Cyl 3 was way low, like so low it should be misfiring up a storm- but then I did a leakdown test, and they all came out almost exactly the same. So, I think I just forgot to open the throttle when I did #3. Also stuck a camera in all of the cylinders, everything looks normal.
It's been running some Restore & Protect for the last 6000 mi (2 changes), after having had the valve cover off and seeing what that looked like. All of the contact surfaces are clean, but everything else is just black. So trying to clean that up a bit.

I think my plan of attack will be to order the assembly, an extra 76mm tensioner pulley, and an idler for good measure. Maybe a spare belt too. And then cross my fingers when I pull the tensioner off that there's nothing wrong with the mounting surface.