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Broken exhaust stud... with a broken extractor in it


jturner

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Trying to replace all the exhaust manifold studs (since one was leaking).

 

The bottom stud on cylinder #4 (the hardest one to get to) snapped below flush, leaving some very stuck stud inside and no way to grab it.

 

I went at it with a left-handed bit + fluted extractor with a lot of body contortion. Well, the extractor snapped, ALSO below flush so I can't remove it either.

 

Will the other studs seal a stock manifold well enough if I leave this broken one as is?

 

Any other options?

Justin Turner

'74 Malaga 

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Pull the head and work it on the bench

 

(I am sure you wanted to hear that advice)

 

As for whether it will be adequately sealed by the remaining 7 studs, that will depend upon how rigid your manifold sealing face is. Tightening stud above it will tend to pull the bottom out, so perhaps go easy on tightening that one. Personally I would give it a go before jumping to pulling the head, though it will always be a temporary measure while I built up to pulling the head. 

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rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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 @Simeon That's what I was afraid of.

 

I JUST dialed in the sidedrafts, these studs are the last (planned) engine work I was gonna do until my bottom end gave up. I have a rally in a week so the head is definitely not coming off right now.

 

It's a stock manifold, so it's not-not rigid. Maybe theres a sealing compound that would help...

 

 

 

 

Justin Turner

'74 Malaga 

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Bummer. I would give it a try, you could try and supplement the gasket with some exhaust sealant but that might cause more problems than it solves. Being a cast iron manifold is probably in your favour. 

 

It’s always worth a shot as you have nothing much to lose. 

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rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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I 2nd pulling the head.... And if you're in a rush, rush it to your nearest trusted machine shop for stud-removal and to clean up the mating face. My guess is it's going to need to be drilled out. 

 

If you've got a week ahead of a rally, you've got plenty of time to get it all back together. 

 

Cylinder head off and on should only take a few hours, max.

 

Don't worry about your side-drafts. if you've got them dialed in and you're careful with their removal you should have no issues in putting them back on. You can even remove the head with them still attached, and remove them on the bench once it's off. When I've done head-work I removed mine this way, and then pulled the carbs on the bench with the manifold (1 piece Ireland unit) still attached as a complete assembly. This makes getting to those tight-access lower nuts allot easier, and it was just a matter of connecting the fuel line and linkage.

 

Good-to-go. 

 

 

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I appreciate the the vote of confidence @2002Scoob.

 

Unfortunately one week really means I have next Saturday and Sunday (my shop isn't at home). I won't have access to a machine shop on the weekend (theres only one in this city) or any way to get parts if anything breaks.

 

And you know how these last-minute scrambles go... I bit off more than I can chew, so I've also got other issues to deal with next weekend already... like a mostly-new brake system that will not fricken bleed.

 

But I'm with you on fixing it instead of ignoring it... just the thought of bolting it back together like this was bugging me. So I bought a right-angle drill, a right-angle dremel, and $150 worth of carbide dental burrs, left hand drill bits, coarse grinding stones, etc etc. This stud is coming out. I'm lucky it's a lower hole and the result doesn't need to seal. I can heli-coil or enlarge to M10 if things go sideways.

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Justin Turner

'74 Malaga 

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You might be surprised how many '02s are running around with at least one nut or stud missing from the exhaust side.  If the manifold is straight you might not even notice the noise or see the black traces on the head unless you are under the car looking for it.  I wouldn't worry about it until you are done with your event.

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Could try the chemical method. Some chemicals eat steel not aluminum. You silicon on a tube filled with chemical to the hole and let it soak overnight. Next morning, clean hole. Bolt and extractor will be dissolved. I think you use Alum but google search the process.

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1976 BMW 2002 Chamonix. My first love.

1972 BMW 2002tii Polaris. My new side piece.

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4 minutes ago, jturner said:

This stud is coming out. I'm lucky it's a lower hole and the result doesn't need to seal. I can heli-coil or enlarge to M10 if things go sideways.

 

Good plan.  I once had a similar incident.  I spent a few hours working out the extractor.  It wasn't quick.  Once I got the extractor out I had a machine shop put in a sleeve (generic Time-sert) so I could still use an M8 stud.  Heli-coils are NOT the best in this application IMO.  Sleeving the hole really is the best way to go in the long run.  Using an M10 stud can be problematic fitting through the exhaust manifold and de-values your head (again IMO).

73 Inka Tii #2762958

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1 minute ago, Stevenc22 said:

Could try the chemical method. Some chemicals eat steel not aluminum. You silicon on a tube filled with chemical to the hole and let it soak overnight. Next morning, clean hole. Bolt and extractor will be dissolved. I think you use Alum but google search the process.

 

Well I bought enough dental tools to do a couple root canals, so maybe I can make my money back that way...

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Justin Turner

'74 Malaga 

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36 minutes ago, PaulTWinterton said:

Heli-coils are NOT the best in this application IMO

 

Does using a helicoil now bar me from adding a timesert in the future? Seems like the sleeve would need a larger hole anyways.

 

I'm not super worried about the head from a value standpoint, as long as the repair works. This car ain't that nice :)

Justin Turner

'74 Malaga 

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3 hours ago, Stevenc22 said:

Could try the chemical method. Some chemicals eat steel not aluminum. You silicon on a tube filled with chemical to the hole and let it soak overnight. Next morning, clean hole. Bolt and extractor will be dissolved. I think you use Alum but google search the process.

 

Wow, never heard of that. I am definitely looking that up. 

rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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2 hours ago, PaulTWinterton said:

Can't answer that.  A machine shop would know the answer.

 

I can't half ass anything... ordered the time-serts. This is an expensive screw up.

 

The last surviving machine shop in SF (afaik) is a one-man show, and theres no way to reach him or schedule his time. You have to show up on a warm day (so his door is unlocked and open for ventilation), and hope he's feeling generous. He's booked months out repairing giant pulleys, etc for all the old elevators in the city.

Justin Turner

'74 Malaga 

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