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Snapped Off Intake Manifold Bolt

Started by HeavyFuel, April 29, 2024, 06:54:47 PM

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Last time I bolted down the intake manifold, No pipe dope was used, so oil weeped up past the bolt.

So today, I attempted to remove and replace the bolts one at a time, adding the dope to each.

Maybe I screwed up and didn't take into account the now lubricated bolts, cause one snapped off before it would take 50 lbs of torque.

Has this ever happened to you guys (probably), and whats my best course of action to remove the bolt?

It is broken off just barely above the surface of the cylinder head.  My math says there is probably about 1/4 inch of bolt sticking through the other side of the head.

Kern Dog

First, what made you think that 50 lbs was the right torque setting? That is a 3/8" shank with coarse threads.
The number I get for an iron intake is 40 lbs.
Secondly, you can weld a nut to it and back it out.

68 rails 4.jpg

Now, this is with a bolt in the frame rail but it was flush with the rail. I just filled the hole in the middle of the nut with weld and backed it out.

68 rails 16.jpg 



I got super lucky.

Thanks anyway for the quick reply, Kern.


I probably knew about reduced torque for lubricated bolts before my brain got lethargic.

Kern Dog

Wow, I never torque the intake that tight. Thanks for the clarification.


were the bolts branded at all? arp or anything like that? stock?


Considering that the intake bolts are threaded into cast iron that's not very thick, I'm surprised the book calls for 50 ft. lbs. I've seen the threads pulled out of the head more often than snapped bolts.
Pardon me but my karma just ran over your dogma.


Quote from: armor64 on April 30, 2024, 07:50:31 AMwere the bolts branded at all? arp or anything like that? stock?

Factory (as far as I know) grade 8 bolts, which will be retired because at least some of them are probably stretched. The replacements are ARP.

Kern Dog

I don't think the factory used grade 8 bolts on anything but suspension.