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Cadillac CTS-V
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Discussion Starter #1
I'm *finally* putting my UUC flywheel in, and of course both exhaust bolts busted when I tried to drop the exhaust. And of course I left them at home (and I'm at work now) so I don't know what thread they are. Anyone happen to know what thread the stock exhaust manifolds need? I'm not sure if I should just drill it out and get a stainless bolt and nut or if I should buy a tap and try to clean up the threads in the stock manifold and get the right size?
Anyone happen to just know it? Any opinions about what grade bolt to use on exhaust manifolds? I've heard some people say stainless, but others say stainless stretches when heated...

Thanks in advance!
 

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Platinum 2004 CTS-V
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4,914 Posts
Call Luke and get GM bolts. At very least he could prob tell you the thread size.

I would drill out/eazy out the old ones. I wouldn't mess with tapping aluminum threads.
 

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Discussion Starter #3
I actually went out and got some 8.8 10x1.5 bolts at lunch. Unfortunately I can't wait to get bolts sent to me as I'm only doing the flywheel this week while my girlfriend's traveling so I can use her Jetta for a run-around-and-get-parts car. ;-) I *could* get them at the local dealership, but I bought some rubber retainers for the wheel well liners there and the bastards charged me $36 for something I got from GM Parts Direct for $12, so I'm not going back there again.
There's actually enough of that bolt sticking out from the manifold to get a pair of vice grips on it, so I'm going to try to back it out more when I get home tonight. Last night I soaked the crap out of it with Seafoam Deep Creep a few times, which I've heard is a decent penetrant, but at lunch I got an arsenal (has "arse" right in it - that's me!) of tools for un-sticking rusted bolts. I picked up some PB Blast, which is the best penetrant I've used, plus some penetrant that supposedly works by FREEZING the bolt and shrinking it. I also picked up a MAT torch and some easy outs. Plan A is to spray it with PB, heat up the manifold to a nice deep red color and then freeze the bolt. I'm not expecting it to jump right out of the hole, but should be cool to try if nothing else.
If that doesn't work I also picked up some new easy-outs and a metric tap set.
I'm doing the flywheel myself because I got a quote of $600 to have someone else do it, but we'll see how much I end up spending before this project is over. At least at the end of it, even if I spend $600... I get to keep the tools! ;-) I already got a nice air ratchet and MAT torch out of it. It's much easier to justify a trip to Tool Town in Sears when your car is 3' up on Jack Stands in your garage. ;-)
 

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ZIP
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51,864 Posts
I think the universal rule of thumb is hit the bolts with WD-40 about a half a dozen times and let it soak a ton. Then try to remove the bolts. Thankfully, my B&B headers and B&B catback ditch the stock way altogether...
 

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05 CTS-V w/ warmed-over LS7
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134 Posts
The stock manifold bolts are M8-1.25 Grade 10.9. They're 30mm long but only ~27mm is threaded.

If you have a heat gun, try heating the bolt and surrounding area until it's hot enough to melt candle wax. Drip hot candle wax on the stub threaded area right where it goes into the head. Keep heat on it until you get your Vise Grips or small pipe wrench secured. It should come out.

This works well on cast iron and should work on aluminum.

If you broke the manifold studs instead of the manifold bolts, use PBR Blaster (nastier, but much better than WD-40) on the studs unless you can carefully heat the manifold/stud area with a small propane torch enough to use the hot wax method. If you try the torch/wax method, pack wet shop rags around anything (wiring, etc.) nearby that can be damaged or catch on fire.
 

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Discussion Starter #6
I broke the bolts, not the studs, but the studs are both rusted to crap and bent too, so I'm considering replacing them while everything is out of the car, otherwise I'm afraid I'll get the exhaust back up and into place before the studs snap, then I'll have to take it down again. :)

Last night I actually ended up drilling out the first bolt. I tried torching the bolt until it was dark red, and I also tried getting the manifold/cat red and then spraying the bolt with "Freeze Off". No joy whatsoever - I don't think you could arc weld that bolt in and have it tighter! I've hammered it, sprayed it with Freeze Out, PB Blaster, and Deep Creep, grabbed it with vice grips, etc, and nothing works!

I also tried easy-outs after drilling it, but they wouldn't bite, almost as if the bolt material was too soft. Then of course my easy-out snapped in the hole. Fortunately it was drilled all the way through so it was easy to tap the easy-out from the back.

I'll try the wax trick tonight on the other bolt. I saw a movie of that on the web, but didn't think it could work better than heating up the bolt and then spraying it with PB blaster. I've heard about the wicking effect of heating up the surrounding area, but is there something about wax that makes it penetrate better than petroleum-based penetrants? Time to dig out the kid's birthday candles! :)

So I got mostly through drilling the first one last night before my brother showed up to help drop the tranny. Last night we managed to get the prop shaft out, drop the tranny, take the shifter off, pull the tranny back out of the way, and get all of the lower bell housing bolts out.

As an aside, I had gotten a quote for $700 to put my UUC flywheel in. At the time that seemed like alot of money, but right now it feels like a freakin' BARGAIN. Between 2 broken exhaust bolts and two studs about to go, I'm going to spend 4+ hours just getting working on rusty crap.

Also, whoever designed the way the hydraulic throwout bearing mounts to the front of the tranny should be shot. All it would take would be a little access hole in the side of the bell housing with a sheetmetal cover over it, and you could get an air ratchet in there. Instead you have to use a box wrench and flip the wrench up and down 200x in a tight space to get the bolts out!

QUESTION: if anyone's done a flywheel in their driveway before, how the hell do you get to the top bolt on the bell housing? It's too close to the firewall to get a deep socket with universal on it, and it's a stud because it's got one of those annoying wire-loom holders, so it has to be a deep socket to get it from underneath I think. And without the tranny hanging off the back, I can't get enough leverage to tilt the engine backwards enough to get it to clear the firewall... Any way to tilt the engine one way or the other without the tranny attached? I tried jacking on the bellhousing to see if I could get it from up above in the engine bay, but with the car up on jackstands I couldn't really see where it was from above. Maybe I'll have to climb right in there. :)

$700 would have been such a bargain...
 
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