Drill exhaust manifold bolt - Remove head or not?

-
DemonSwede

DemonSwede

Active Member
Joined
Sep 19, 2022
Messages
26
Reaction score
17
Location
Stockholm Sweden
As the heading suggests, after having failed to remove the bolt using a bolt extraction tool (and of course managed to snap the tool itself in the bolt!) I most likely need to drill and re-tap the upper rearmost drivers side manifold bolt. The engine is in the car and I have reasonably good access as the manifold and steering box/shaft is out. But I’m still scared to drill it on site and get it straight as the bolt is dangerously close to the water jacket. Do you guys think I should pull the head? I’m planning to replace the intake manifold anyway this winter so maybe it’s just as well to just take it out? What would you do? Thanks!
 
Agree that you should pull the head, especially since the extractor is snapped off in the broken bolt.
 
Need to drain down the coolant for starters as the end manifold bolts go right into the water jacket.

@Oldmanmopar and his machinist/engine builder son have good luck using a welder to get them out.

One technique is to weld a washer to the broken stud first then tap tap tap then weld a 1/2" nut to the washer so you can get a wrench on it, tap tap tap then try and turn it out.

Heat from the welding helps to break it free.

Good Luck

Screenshot_20230107-074923_Gallery.jpg
 
If it was me, I would remove the head and take it to a machine shop. And I'm not suggesting an engine machine shop but one that is HIGHLY skilled in one-off machining...hard to find these days. I'm not sure if you still have a bit of the extraction tool stuck but if so, they can use carbide tooling to machine straight through, leaving only the threads which can be picked out. I'm not a machinist but the machinist instructor where I used to work would do this on a regular basis and it always worked. Hand drilling will never be straight enough and while I agree the welding trick can work, it is always a crap shoot and the less you end up handing over to the machinist in the end, the more he will appreciate it.
 
Thanks guys, seems like an easy decision to remove the head! I would definitely have tried the welding method but the car is parked in winter storage and I’m not allowed to use a welder in there.
 
Another question, since I’ll probably need to replace the head gasket for the head I’m removing, would you suggest removing the other head as well and replace both gaskets? I didn’t build the engine myself and I don’t know what gasket is used and what thickness.
 
I wouldda already had the head off. If the head you have to take off even LOOKS like it needs a valve job, I'd snatch the other one and get r done. Now's the time.
 
Yes remove head and find a small tool and die shop that does repair work on tools and dies as in die cast dies and/or plastic injection molds. Have their most experienced journeyman cut out the screw with a carbide cutter on a Bridgeport type vertical milling machine. Express how rare and expensive the head is and not to **** it up. Guaranteed they will have someone that can do the job as it is common practice. Make sure you express how you want it done with a milling machine, clamped to the table.

Welding nut or whatever or even using a hand drill is hack work likely to **** something up.

Then as RRR suggests, time to service the heads, valve job, fresh springs and such. You won’t regret spending the money for a job well done the best way.
 
Picture the head gasket and measure its thickness, have the machine shop do it if you can’t. The guys around here will steer you the right way to go with new head gaskets.
 
adter you drain the radiator, then remove the pipe plug at the bottom of the water jacket. That way you won’t get coolant inside the cylinders and a mess on the floor.
 
I would pull the Head, Easier for sure. Had this issue back in 2012 when resto started, broke the Easy out due to impatience and seemed bad. Engine was out though.

Nice thing is BB heads open to the water jacket, and popping a freeze plug to get the slug out was easy after drilling and punching the outer section in.
 
If you don't have an oil consumption problem, I would leave the valves alone, seals, maybe. Just my opinion, valves and rings should go together, overhaul.
Depending on how the stud removal goes, use a very good sealer on the new stud, let it set after installing, cure time before antifreeze.
Definitely remove the head and find a machine shop.
 
Last edited:
Here is a quick 15 second video on removing a broken bolt out of an aluminum head.

Welding the large nut on "Red Hot" sinks a lot of heat down into the bolt threads to help it break loose.


 
Update. Unfortunately I didn’t have any success welding a nut onto the stud. After multiple attempts I gave up as at that time the weld had stuck to the hole making it impossible to get the old stud out.

So I need to drill, tried that as well but quickly realized I can’t do it with a handheld drill as my first attempted hole veered off.

I’m thinking I need to first fill up the hole by weld using a cast iron rod and then re-drill it using a drill press. Any better suggestions?

The stud hole on the other side goes straight into the water jacket so I’m thinking I can drill the hole straight through. Would you guys try to just tap it with a 5/16 tap or use helicoil or similar?

Also while I’m at it, do you suggest I weld the exhaust crossover shut or will the gasket be enough to seal it for my RPM Airgap intake?

1FD0426B-6C69-4C5F-8512-1718C7F0BE7A.jpeg


BBD65A58-D676-4427-94A3-DDEDB0D255B7.jpeg
 
Can try tapping the off centered hole you have there. Have it predrilled to the proper taping size for 5/16". Careful cause if you hit the broken easy out . . .

Have had that happen and just retapped them off centered. Not ideal but can work. Install and seal the stud with high temp rtv and good to go.

Might have to cheat the exhaust manifold flange to keep the manifold In proper position.

Screenshot_20230127-082330_Firefox.jpg


No to welding the exhaust cross over shut.

There are intake manifold block off gaskets available.

__________

Worst case senario, can always walk It over to your local engine machinist and they can Helicoil it for you.
 
Just stop and take the head to a machine shop. You need to put it on mill and mill the hole oversize for a helicoil.

The more work you do the more you are going to make it harder to repair.

No need to weld anything with the RPM AG. Put the gasket on and send it.
 
You must log in or register to reply here.
-

Back
Top