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Should probably get them surfaced ?
Exhaust manifold bolts
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Not sure I quite subscribe to that .
Thing is, they normally crack under the heat shields where they sweep up and over.
To start , look for marks showing evidence of heat spots on the shields
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The stock GM exhaust studs have not cracked in my experience. I have always reused them.
No offense but this is really bad advice. You have just been getting lucky.
Considering how cheap bolts are, do not even risk snapping an old one off in your head.
Caddylack is right, I would never reuse those bolts unless you have put them through an intense cleaning. Plus stainless bolts beat out those bolts every day. It is a no brainer.
Wow, saved me a lot of typing by taking the time to go back and find this. Just to toss in another wrinkle, check and consider the TSB detailed by Post #15, stemming RH manifold cracking under hi-heat, hi-speed, hi-rev operation with stock manifolds. Exhaust Manifold Restoration
And then Post #19 RE: TSB for bolt length issue in '94 heads.
And then Post #19 RE: TSB for bolt length issue in '94 heads.
Ken, pardon my picking nits and edits but in light of the recent replies I had to read it more than once myself. Unless you mention otherwise I'm taking that to mean just the PS studs used way up front for the alt. brackets. There was a DS center stud on some years/makes but it wasn't used for anything - my '96 Impala SS having come with a normal bolt in that location.
Your point is taken that the bolts with the stud extensions just don't seem to fail and in all these decades I can't even remember anyone recounting any breaking outside of the rear two each bank. Of course anyone in the biz ::cough Gerry:: is going to come across all manner of horrors, and all bets are off for any poor bolts that were either re-installed without their collars, or with collars but over-torqued so they couldn't do their job.
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Since we are talking about exhaust and everything is going to have to come apart what is the life expectancy of these catalytic converters? I have a proximately 80,000 miles on the originals. I was able to locate one good Nos passenger side but I’m finding it impossible to find an Nos driver side. I have read somewhere that these things can be cleaned? Or is that just an old wives tale.
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The original exhaust manifolds also seem to be long gone in Nos.
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Is able to find one gentleman that had these parts but he still has the car and he’s not willing to part with them until he gets rid of the car.
I would never replace a cat unless I got codes for it. You are pissing money away.
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My engine has three of those studed exhaust manifold bolts DS not used .
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I understand where you’re coming from about pissing money away. Thing is I would like to get through the job as quick as possible once it’s started. Getting machine work done to refresh gasket surfaces is expensive and time consuming. Also finding someone willing to do that type of work isn’t easy but I willing to give it try.
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I have someone in mind I just haven’t run it past him yet. He is an engine builder just don’t know if he’s willing
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From the cars that I’ve taken apart either in salvage yards or parts cars that I have purchased usually they need attention at the gasket surfaces
I like the period. maint. angle. But instead of labor and cost to replace the cats, apply exactly the same labor effort but 'lot's less' dollars on just replacing all the O2es. Urban legend is they go 'weak' and mess with air/fuel before actually bad enough to throw a code. From my experience don't even attempt to unscrew them until cats are removed and in a bench vice. I use lots'a heat and quench with PB Blaster. And impact is good too.
And word is that ACDelco (even though just another overseas-built nowadays) and DENSO are acceptable quality, NEVER use Bosch. Though that may have changed in the last 10-15 years as well.
And word is that ACDelco (even though just another overseas-built nowadays) and DENSO are acceptable quality, NEVER use Bosch. Though that may have changed in the last 10-15 years as well.
Interesting to note for the future.
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thank you for the information. I will look into AC Delco and Denso.
I am confused where you are getting gasket resurfacing for the cats? Cats are easy to pull out in the event you need to. I do not resurface the gasket spots for heads and manifolds. Razor blade and scrape scrape.
Bosch used to be OEM for GM at some point I am not sure.
Replacing the O2s is good but personally another thing I wouldn't do until I start getting codes for it. Just a waste of time, effort and money. You aren't really saving or preventing any major issue from occurring in the event of an O2 sensor failure so what is the point?
I assume he is talking about the gasket surface between the manifold and cat. It's a flat flange.
Before, it sounded like he was talking about the flange that bolts to the head.
@1996 roadmaster where do you live? Does your state/county have emissions inspections for vehicles this old?
If not, I highly recommend deleting your cats for the simple reason that they are worth a bunch of money.
Whoa, hold up...
I know from experience that o2 sensors are a BIG deal on these cars. I consider it one of the items that you should absolutely replace preventatively, and ONLY with Delco/GM.
It's just impossible to really fine-tune anything if the o2 sensors aren't reading correctly. The dyno tuners around here expect your o2s to be fresh out of the box when you hit the dyno.
Keep in mind that changing the o2 sensors periodically will ultimately save you from that horrible torch/breaker bar job that many of us have had to undertake.
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