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Old 02-20-2021, 06:44 AM   #5
ike84
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Join Date: Oct 2020
Location: KY
Posts: 1,216
Quote:
Originally Posted by husker boxster View Post
I'm hoping to change out the driver's side exhaust manifold today (bad cat). When removing the exhaust manifold bolts going into the engine block, should I...

1) Give 'em the beans and hit them with an impact wrench

or

2) Carefully hand loosen them

I'm really afraid of breaking them off so I'm wondering if either of these approaches is better. I'm leaning towards #1. I've been squirting them with AeroKroil several times over the last 24 hrs in preparation of the extraction.
Please, for the love of all that is holy, do not use an impact on these.

I agree that repeat oiling and whacking over several days is the best first step.

I watched an interesting video a mechanic made about removing seized header bolts. He would actually tighten them until you could feel the cracking of the rust, then loosen quarter of a turn, then tighten again, then loosen again, etc. Take your time, don't force it, and don't actually remove any of the bolts until they are all cracked free. Start with the front and rear ones first as they are usually the hardest ones (and will only get more difficult if you save them for last). This was the technique I used in mine and 11/12 came out fine. The integrity of the metal on the rear most bolt on driver's side was so poor that I could actually feel it twisting but not breaking free. That one had to be drilled out.

Do yourself a favor - when you replace them, don't use standard hardware. Go with SS studs (tightened with hex key for your toque wrench) followed by copper plated nuts. Using dissimilar metals will reduce the risk of contact welding as corrosion and heat cycles do their damage.

Let me know if you need part numbers for the studs and bolts. There are "porsche specific" kits that will run you well over $100 but I bought universal parts for $25 and they worked just fine.

Btw, when I dismantled mine, I found that the top not on the triangular flange between header and midpipe were spot-welded by the factory. I'm not the only one to have found this, but it doesn't seem to be universal though.

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Last edited by ike84; 02-20-2021 at 07:04 AM.
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