Parts aggravation

Started my beloved '02 Aurora while parked in front of my house. Thought I heard a loud thump but wasn't sure because the radio was a tad loud. Noticed that power steering was absent, and the charge light was illuminated
brightly. Figured belt broke. Shut it down. No time to check now. Do it tomorrow.
Wasn't the belt. Idler pulley bolt sheared off almost flush with the alternator's mounting flange. Hard to reach. Not enough left to get hold of with Vise Grips. Can't drill it. No way to get a drill down in there. After looking over the arrangement under the hood my brilliant idea now is to take off the thermostat housing and radiator hose in hopes it will allow me to slide the alternator off the bolt's remains and get a much better shot at it.
Decided maybe the thermostat should be replaced as preventive maintenance after the housing is off. Headed off to the dealer feeling good about "keeping my GM car all GM."
They could order the Tstat housing seal, but the new thermostat comes as a housing/Tstat assembly. Right around $40. Choke! Gag!
Inquired about a new bolt for my idler pulley. They don't sell just the bolt. Have to buy the pulley "assembly" also about $40. More choking and gagging.
Decided to not replace the Tstat. Headed off to NAPA to get the seal. Nope. They don't even sell the seal, just the assembly. About $33 my discount price.
How about an idler pulley? Nope. They just sell the tensioner.
Got on line and queried Advance and AutoZone sites. Struck out there although they did list a Prestone Tstat. GM Parts Direct looks promising.
Please forgive my ranting. I would like to know more about this thermostat/housing assembly deal. Have never seen it up close and personal yet as it's still on my machine. It truly can't be serviced by putting a new Tstat in it?
How about that bolt for the idler? Can I just go to a place that sells metric bolts and find a suitable replacement, or should I just spring for a whole new pulley/bolt assembly?
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Greetings,
I can't speak for the thermostat housing assembly, but I have an observation concerning the pulley. Typically, there are two types of pulleys on single serpentine belt systems - an idler pulley and a tensioner pulley.
An idler pulley is just bolted to whatever piece of metal happens to be right where the pulley is needed, but a tensioner pulley is attached to a spring-loaded arm that applies constant tension to your serpentine belt. If you sheared off an idler pully then just buy the pulley (it comes with a new bolt and it's pretty inexpensive), but if you sheared off the tensioner pulley you will most likely have to purchase the entire tensioner assembly (arm, pulley, bolt, tensioner spring, etc. as a one-piece unit). Most often the bolt for this pulley is pressed into the end of the arm and is not replaceable because turning this bolt is what allows you to pivot the arm and release tension on the belt. The single bolt that passes through the tensioner spring usually holds the assembly to it's mounting point and won't affect the spring at all so you can remove it without having to worry about unloading the spring.
If you're going to replace the tensioner you might as well replace the idler pulley as well while your belt is off. The idler pulley is much easier to replace because the bolt actually can be removed, and if you're into doing preventative maintenance you might was well so that you have both pulleys brand new. If not, hey it's only 3 years old and still has some miles left on it.
Cheers - Jonathan

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Jonathan,
My tensioner assembly is just fine. It's the idler that bit the dust. I'm not too keen on replacing the tensioner as a preventive measure because it costs upwards of $80. Buying the whole new idler with bolt doesn't seem all that inexpensive to me at $40. Maybe that's because I'm tighter than two coats of paint. Thanks for your input.

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Greetings,
Well the next thing you have to think about is just why did the bolt shear off? An idler pulley is an overly simple piece of machinery with nothing more than the pulley, a bearing and a center bolt. The only thing that can really go wrong is the bearing, and if the bearing fails then you will have to replace the entire unit. If the bearing did have a failure (or was starting to fail) and was starting to score the bolt causing it to shear off then just replacing the bolt ain't going to do much for you except delay the problem.
If you're dead set on not purchasing the entire assembly at $40.00 (I'm sure you can do better from an online supplier), then you can take the pulley to a place that does bearings and have a new set pressed in. They should also be able to advise you on a new bolt (grade 8 I believe, not difficult to find), but frankly by the time you get all of that done you will have spent just as much in time and effort to repair the old pulley as you would to simply replace it with a new one for a few bucks more. The prime reason why certain parts come as complete assemblies is to reduce assembly and repair times.
My advice is to take the part number from the pulley assembly and enter it into parts websites from other GM products (since parts numbers are pretty universal throughout the entire GM line). If your lucky, the same pulley will also be used on another GM motor and you may be able to get it cheaper from Chevy or Pontiac.
Cheers - Jonathan

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your T-Stat / housing reminds about the 5.3 V8 in the Silverado that has the water pump & timing cover as one unit or something like that. And i think the T Stat housing is also part of the puzzle piece. Great engineering .
I thought about replacing my belt tensioner in 04 but I didn't.
Good Luck
Harryface 05 Park Avenue, 32,672 91 Bonneville LE 304,656
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Silver Surfer wrote:

Not sure if you have a V-8 or V-6 Aurora. I just checked for the V-8 version and rockauto.com seems to list all of the parts you talk about, including separate thermostats, gasket and housing. One of the housing listings notes that the original housing is supposedly stamped steel ????
You probably can get a good replacement bolt at an industrial fastener supplier in your area. You will need one of proper dimensions and grade. Often the Home Depot/Ace Hardware stuff is not of the quality level you really want for a high stress application.
John
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Bolts are bolts, my advice is to use the best bolts possible, use Grade 8 in areas where maximum strength is needed. Stainless Steel bolts are great if you keep cars " forever " I use them, with SS nuts on exhaust systems, gas tank, thermostat housing, electrical [ ground ] and any other troublesome area.
Would a Speed Shop sell a better Idler, or is a factory motor sport version available ? Might be worth it to check parts dept on a slow day, at more than one dealership, as attitude toward the unusual is met with smiles, scowls, and little in between.
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