I'm replacing the front(firewall side)(stock)exhaust manifold on my 88V6. I got a replacement manifold at the local recyclce yard and the bolt that attaches the crossover pipe to the manifold is frozen solid in the nut. I've had it soaking in Yeild rust buster all day, no effect, so it looks like I'm gonna have to cut it off,drill and tap the nut. Anyone know what the thread is for this nut???? Thanks

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fasteddie_91932

quote Originally posted by ED Beard: the bolt that attaches the crossover pipe to the manifold is frozen solid in the nut. I've had it soaking in Yeild rust buster all day, no effect, so it looks like I'm gonna have to cut it off,drill and tap the nut.

It's 8 x 1.25.

Put some heat on it and it'll come out with no effort at all. That'll be lots easier than cutting, drilling, and tapping.

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Doug Chase
Duvall, WA
'88 Fiero Formula 5-spd (autocrosser)
'88 Fiero GT 5-spd (daily driver)
'85 Fiero GT 4-spd (rally car)

try this post https://www.fiero.nl/forum/Forum2/HTML/020032.html

Thanks for the thread info. I am an old time mechanic/machinist and I'm really not up to speed on metric threads. I probabably did not give enough info the first time , This manifold that I was trying to get the bolt out of only had 1/4 inch or so of bolt sticking out of the nut in the manifold on each side. It was d#*mn near impossible to get channel locks or vise grips on, in addition to being rusted solid. I cut the remainder of it off today, drilled it and now I'm off to Home Depot for a tap, all I have in my garage are good old USA thread taps. Thanks

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fasteddie_91932

A little trick of mine for next time.

When I replace the crossover to manifold bolts, I use 7mm bolts. These pass through the nuts that are welded to the manifolds. I then use an appropriately sized nut and washers to secure the crossover to the manifold. This way, no matter how rust and beat up the bolts/nuts are the next time you have to remove the crossover, you can just cut through(Dremel) the 7mm bolt and easily separate the crossover, never having to deal with rusty bolts again. a HUGE time savor. I do it everytime now.

That's a great idea on the 7mm bolts and nuts. Too bad I didn't read that reply before I bought that tap and retapped the nut. Oh well I guess that I needed the practice with the tap. If there is ever another next time(OH PLEASE NO NEXT TIME) I'll use your idea. Thanks

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fasteddie_91932