Help! Breaking free an exhaust manifold

[Brewgyver]

Yes, taking the manifold to a machine shop might be your best bet.
But I would at least give it a try with the proper tool, that being a properly sized drift punch.

You certainly want to avoid damaging that manifold, they're about $1,500. You can get a cylinder head for a fraction of that.

The broken stud in the head will often come out without a real fight, as you saw with a couple of the other studs. I had two come out with the nuts when I replaced the manifold on my A4.

[jimbunyard]

Originally Posted by Cap Bill Des

Hi, this is Bill again, the OP.

Well, another pretty long day, and I'm not sure if we've gone forward or backward.

After reading all the great input we decided to:
A -Stress the joint between head and manifold with three wedge screwdrivers right around the stuck stud
B- Direct the torch right down the pressure cap opening on to the "rib" of cast iron that surrounds the stud ( it is the front upper stud, directly under the cap
C- After 2 minutes we started tapping the outside of the manifold.

The plan was to do this process every 10 minutes and hope the thermal cycling would break the bond between stud and manifold.

Getting ready for just the second cycle I was tapping on the screwdrivers...and bang!,. The stud broke at the block/manifold joint.

So...
We have the manifold off with this stud in it. We tried a little more heat and banging on a cement curb, but it is not breaking free.
We also have a stud broken off about 1/16" deep the the head(which is on the engine)

What to do? I'm not experienced at this, so I've got a call out to a recommended marine diesel shop to have someone come out and remove the broken stud. There is very good access and room to approach the stud. I guess we'll see in the morning.

On the manifold- do I just take it to a machine shop and have them drill the stud out?

I'm really hoping we can save both the head and manifold.

Thank you for all the help so far, I have been very pleasantly surprised at the depth of knowledge offered up. I just hope we can get this motor back together, and not have to spend our whole summer cruise stuck in one spot!

I'd say forward...

It's worth a try, using Wings proposed method, to drive the stud out, but if it doesn't move with a couple solid blows you're probably wasting your time. Sometimes studs rust into place with an extremely hard form of rust that locks them permanently in place, necessitating their being drilled out.

A good machine shop will probably be the most economical solution; a better one will mill the end of the stud, center drill it and then finish drill it on a mill, leaving the hard rust to be reamed out later. A good one will center punch the stud, and drill it out on a drill press, rust and all. Either is perfectly acceptable. (and the cost may not be indicative of which method is used...)

Removing the broken stud in the head can be tricky, even for the experienced. If your recommended mechanic is self-deprecatingly quiet and confident, and starts with a center punch and a left-hand bit that is half the diameter of the stud, then he'll most likely be successful. If he doesn't, I wouldn't let him touch the engine.

If mistakes are made, the hole can be tapped for a heli-coil, but it is much better to use the original threads...

Perhaps this is a bit trite, but upon reassembly, coating the studs and threads with never-seize is, in my book, a necessity.

[boden36]

I had a similar problem a couple of months ago with the exhaust manifold on a 1927 Austin 7. I tried brute force with wedges and ended up pulling the stud out of the block and cracking the block in the process! I should have worked a hacksaw blade through the gasket and cut the stud that way.
To get the broken stud out of the manifold, I had to properly support the manifold, heat the area to red hot and pound the life out of it using a heavy hammer and a drift. It took a lot of heat and hammering to get it out.
Another probably better way would to be to take the manifold to a machinist who could take the stud out accurately with an end mill. Have him clean up all of the other holes at the same time. Put anti-seize on the studs before you slide the repaired manifold back on.
To remove the broken stud from the block, bolt the manifold back on, shimming around the remaining studs with bits of an old aluminum drink can to make sure it is exactly centered.
Make some bushes that will fit tightly in the remaining manifold hole, and drill them to take ascending sizes of drills. The manifold will act as a jig to center the drill. Try using a left handed drill, which might just screw the broken stud out.
Use the same bushing method when you are tapping the old stud hole for a thread insert. These are really easy to install.


Regards,
Richard.

[wingless]

Originally Posted by wingless

Put the loose manifold into an ice box for an extended time.

Remove the ice cold manifold and use a MAPP torch to safely / quickly heat the area around the broken stud, but not the stud. Heat both sides of the manifold.

Quickly use a hammer and small drift, looks to be about ¼" diameter to knock out the broken stud.

The other method to remove the broken stud would be to use a shop press and an appropriately-sized guided drift to force out the broken part.

Note that I had been VERY surprised as to how handy the shop press is for many, many tasks.

[jimbunyard]

Originally Posted by boden36

...To remove the broken stud from the block, bolt the manifold back on, shimming around the remaining studs with bits of an old aluminum drink can to make sure it is exactly centered.
Make some bushes that will fit tightly in the remaining manifold hole, and drill them to take ascending sizes of drills. The manifold will act as a jig to center the drill...

I use 2" aluminum duct sealing tape (not duct tape) wound evenly in the appropriate direction for the both applications, as by varying the length you can make fairly precise adjustments in the clearances.

[wingless]

Note that if this were mine, I would replace ALL of that hardware, including the studs still attached to the block.

My method for removing a stuck fastener is to always tighten it first, until it just breaks free. Then loosen / tighten in slightly larger arcs each time.

Lubrication is used throughout the process.

A pair of curved-jaw locking pliers would be handy for grabbing the stuck studs for removal.

The manifold would be polished and painted prior to replacement. The gasket surfaces would only be scraped clean.

[a64pilot]

Pull the head and take it and the manifold to a machine shop.
While the head is there, go ahead and have the valves done.

[RaymondR]

Originally Posted by a64pilot

Pull the head and take it and the manifold to a machine shop.
While the head is there, go ahead and have the valves done.

Yep, probably the best bit of advice in the entire thread.

And, you can clean it up and give it a real nice paint job.

[Cap Bill Des]

Hi, Bill here again, the OP.

Well, progress! I ended up with a machine shop to remove the problem stud. They said it never broke free, and the worked up in full-depth drilling, finally just ran a 0.250 drill through the manifold clearance hole. I'm guessing it was corroded in place, as some has said it might be.

So now we're down to the final 1/4" of that stud which snapped off in the head, about a 1/16" inside the head.

My plan is center-punch, a few taps, then a 1/8 left hand drill. I also have a 3/16 left hand drill, but I'm going to start small.

Looking ahead, optimistically, whatever torque should I use on the new studs into the head?
A chart for metric bolts give figures from 6 to 13 ft-lbs depending upon Class of bolt. My studs are not bolts and they don't have any markings. ( By the way, I was assuming anti seize on the studs and considering that as "lubricated" on the torque chart).

Thanks for any advice!

[wingless]

Thanks for the update.

The threads on the cylinder stud holes should be properly chased using the correct-size tap.

The replacement studs (replace all with new) should be screwed in hand tight. I use On and Off exhaust thread lubricant. That product is NLA, but there are equivalent products. I would also coat the stems. The lubricant will smoke during initial usage.

The nuts retaining the manifold to the studs should be torqued to specification.

[Cap Bill Des]

Thank you for clarifying how to put the studs in the head- I'm sure it's obvious that I haven't done a lot of work on engines.

I will chase the head threads..

So I guess I'm asking the torque on the nuts. The Service Manual gives specified torques for 16 "Important Parts", from head bolts to crankshaft nuts, but no mention of exhaust manifold nuts. They follow with a table of Bolt Torques, which for M6 had three ranges, for Standard and two Special classes, with different designations that start with"S". The total range across Classes is 6-11 ft-lbs.

So what to use? I surely don't want to break a brand new stud after coming this far!!

Thanks again...

[jimbunyard]

Originally Posted by Cap Bill Des

Hi, Bill here again, the OP.

Well, progress! I ended up with a machine shop to remove the problem stud. They said it never broke free, and the worked up in full-depth drilling, finally just ran a 0.250 drill through the manifold clearance hole. I'm guessing it was corroded in place, as some has said it might be.

So now we're down to the final 1/4" of that stud which snapped off in the head, about a 1/16" inside the head.

My plan is center-punch, a few taps, then a 1/8 left hand drill. I also have a 3/16 left hand drill, but I'm going to start small.

Looking ahead, optimistically, whatever torque should I use on the new studs into the head?
A chart for metric bolts give figures from 6 to 13 ft-lbs depending upon Class of bolt. My studs are not bolts and they don't have any markings. ( By the way, I was assuming anti seize on the studs and considering that as "lubricated" on the torque chart).

Thanks for any advice!

With a little luck the broken-off part of the stud will spin out when you drill it with the 1/8" bit. Make sure you get as close to the center as you can when you center punch it, because if it doesn't spin out, 3/16" is the OD of the female threads, and you want to preserve as much of them as possible.

To effectively chase the threads, you need a bottom tap, as the hole is only about 14-15 mm deep. If you can't get one, a regular tap can just be ground off so that it penetrates enough to clean all the threads.

The studs should be screwed firmly into the head, not necessarily full torque, but perhaps at least half or so. It's probably not recommended to use vise grips as the studs may be coated, but you shouldn't have any problems double-nutting them in. The reason is so that you get an accurate torque when tightening the nuts.

Standard grey Permatex never-seize is adequate in this application; the manifold temperature never gets hot enough (unless you run it without water!) to require a specialty coating designed for 1000 F. Coat both the threads and the shaft of the stud.

If you can't find the recommended torque, 10-12 ft lbs will be fine. Tighten the two center nuts first, then the nuts on the outside. If you don't have a torque wrench, after snugging up the nuts as above (compressing the lockwashers) tighten about a fifth to a quarter turn, in the same pattern. A ten mm box end wrench about 4 inches long is the perfect tool for this.

After about 25 hours, recheck for tightness.

[Cap Bill Des]

Hi, this is Bill, the OP, again. I think from the point of view of this three- Manifold that would not release-. Success has been achieved.

Center-punching the stud broken in the head was not really working- the broken surface was so irregular.

What did work to start was using the Dremel with it's standard 1/8 drill at 30,000 rpm. It cut into the stud do well, and the Dremel is so light and maneuverable, that I could steer it to create a centered start hole.

Then the left-hand drill running backwards in the regular drill dug right in and brought the stud out.
Success!

So the new studs are in and the manifold is torqued up. All good!

The whole purpose of this project is to install the "new" alternator bracket for this Universal M25 engine. The new bracket hangs right on the manifold studs. I may start a new thread- because this new bracket is not working for us! There seems to be no range of adjustment- the alternator is either swung in against this new bracket, or just swing out a tiny bit the lower arm of the new bracket starts hitting the "fan blades" of the alternator. Even if I can find a belt that fits, I don't think there is any range for belt tensioning.

Well, we'll see, but that may be another thread!

Thank you again for all the shop skills advice- it was really helpful!

[wingless]

Great news!

Thanks for the update!

It has been surprising to me how well my left hand cobalt drill set bits work to remove broken fasteners every time it is required. I haven't needed to use the extractor tools yet because the drill bits always remove the part.

Good luck getting your new bracket / belt to work. Post an image showing the problem please.

[Stu Jackson]

Originally Posted by Cap Bill Des

.................................................. ...

So the new studs are in and the manifold is torqued up. All good!

The whole purpose of this project is to install the "new" alternator bracket for this Universal M25 engine. The new bracket hangs right on the manifold studs. I may start a new thread- because this new bracket is not working for us! There seems to be no range of adjustment- the alternator is either swung in against this new bracket, or just swing out a tiny bit the lower arm of the new bracket starts hitting the "fan blades" of the alternator. Even if I can find a belt that fits, I don't think there is any range for belt tensioning.

Well, we'll see, but that may be another thread!

Thank you again for all the shop skills advice- it was really helpful!

Congratulations!!!


OK, bracket adjustment: you HAVE TO read these: I was the subject of Maine Sail's original "how NOT to do it" photo and have since corrected it


Do you have a picture of your alternator in place?


Critical Upgrades CRITICAL UPGRADES - DO THESE OR ELSE!!!

not all bracket related but read through the whole topic to find them

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment 101 IMPORTANT

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment

Maine Sail's www.marinehowto.com site has more.


Please check these before you give up.