Exhaust manifold nut problem--need ideas

[Sam Buchanan]

I have a stripped nut!   ?

 

The leaky exhaust manifold gaskets on the P15 have lately increased their bark telling me they need attention. I've put this job off for a long time due to dreading all the problems that can arise. This morning I decided it was time so out came the fender liner and carb. The tally so far is two studs backed out, two studs broken off, and eight nuts removed. All four of the heat riser bolts snapped off leaving stubs in the exhaust riser. All that remains is one of the nuts on a long stud buried in the recess of the manifold.

 

 

 

The problem is this nut is just spinning on the stud and won't come off. The other long stud snapped off.

 

How to remove this nut in the very limited space? I'm inclined to try welding the nut to the stud then either backing out the stud or more likely...breaking it.

 

I am open to suggestions and hope someone has a good solution. I can't remove just the intake for better access because of the broken stubs in the heat riser. I've considered sawing off the stubs but don't know if I can get to the ones next to the block.

 

REALLY hoping the brain trust can come up with ideas......and thanks in advance!

Edited October 2, 2019 by Sam Buchanan

[Plymouthy Adams]

use a nut splitter....appears you have room for it in the spaces shown...slit the nut then when the manifold is off and out of the way...I would heat the stud with the torch one good cycle and use a stud removal tool to extract it...the tool give  you a greater bite along a larger portion of the stud.....

Edited October 2, 2019 by Plymouthy Adams

[Los_Control]

4 minutes ago, Sam Buchanan said:

I'm inclined to try welding the nut to the stud then either backing out the stud or more likely...breaking it

IMHO, you going to want to replace that stud any ways.

 

I think I could take my dremel tool in their and cut that nut off.

I think the real goal here is to remove the stud, weld the nut to it and remove both.

No way I would want to re-use that stud if the nut is spinning on it now.

[RobertKB]

Good ideas above so I won't add. However, you indicate you have dealt with 12 studs and their bolts. There are actually 13 as the last one is kind of hidden behind the manifolds and not obvious at first glance. Maybe you already know this and if so please ignore this post.

 

Good luck with your project!

[Plymouthy Adams]

as I read it Robert, its lucky number 13 that is eating his lunch spinning in place...

[Sam Buchanan]

Yes, it is lucky #13 that is causing the problem.

 

I would love to split the nut but how do you get a splitter into this recess?

[Plymouthy Adams]

well I was only going by the picture......it may not be enough room...so try the following as a first option...

insert  a screw driver or other properly size pry bar/tool to get behind the nut and apply some directional force as I use a wrench to again try to remove the stripped nut….

[Sam Buchanan]

I don't think you guys understand the location of this nut. 

 

Imagine a nut in the bottom of a spark plug hole........there is no getting behind the nut......but I may try making a tool out of a screw driver to see if I can put enough force on it to make it "bite".

 

Edited October 2, 2019 by Sam Buchanan

[Los_Control]

If you weld the nut on, then the stud comes out, would be a perfect world.

Good chance the stud may break when pulling it out. Did any of the others?

either way, a good chance if it breaks, you will have the manifold out of your way. Now you can apply heat directly to the stud and break the rust free.

50/50 chance you may have room to weld another nut to it.

Worse case you will have to drill it out and tap it.

 

These nuts I believe are Brass, and would be a soft metal. As @Plymouthy Adams stated above.

If you can find some way to get pressure behind the nut, and spin it off, maybe the threads would still be good.

 

I still would want to replace the stud, So many heat cycles over 75 years, pretty sure my wife would replace this stud after 30 years if she had a chance.

[soth122003]

Hey Sam,

 

Looking at the pics, you have the room to use an air chisel. Make sure the blade is sharp. Place the blade as close to the stud as you can and try short bursts with the chisel to try and break or split the nut. Some one else posted the nuts were brass and they may be right. They are made of a softer metal to expand and contract with the heat cycles of the manifold. Just remember if you go this route use short controlled bursts and check after each hit to see the progress.

 

Joe Lee

[joecoozie]

I have used this method many times.

Drive a wooden wedge between the manifold and the engine block. Pick a spot close to the stud/nut you are working on but make sure it is a "beefy" area of the manifold. Don't want to break the "ear" off.

This puts pressure on the nut from the manifold. Use your socket to try and back the nut off. If it is working the wedge will become loose and thereby will need to be tapped in again to repeat the process until the nut comes off.

[kencombs]

3 minutes ago, joecoozie said:

I have used this method many times.

Drive a wooden wedge between the manifold and the engine block. Pick a spot close to the stud/nut you are working on but make sure it is a "beefy" area of the manifold. Don't want to break the "ear" off.

This puts pressure on the nut from the manifold. Use your socket to try and back the nut off. If it is working the wedge will become loose and thereby will need to be tapped in again to repeat the process until the nut comes off.

second vote for this.  I usually use a really long mechanics pry bar though.  And, NO manual tools, it's amazing how fast my little 3/8 impact will spin those off.  And, greatly reduces the breakage, rounding and stripping.  JUst hold constant pressure on the pry bar and pull the trigger!

[Veemoney]

Joecoozie has the right idea, If you have a putty knife it will slip in easily then apply some pressure while turning the nut. you can twist the putty knife with a crescent wrench right next to the stud. 

[Sam Buchanan]

The manifolds are stuck tight to the block.

 

But I got the nut off. I removed the remaining fender liner (should have done this when I puller the lower liner) and was able to get a Dremel with a cutting bit into the recess.

 

 

Yes, the nut is brass, MIG weld wouldn't have worked and the threads in the nut were completely gone. All the fasteners are off, now need to find a way to get the manifolds to release from the block without breaking anything. I think the biggest problem is those two lower long studs appear to be a very tight fit. I'll try a wood wedge to see it it will start moving.

 

Thank you for the suggestions thus far!

Edited October 2, 2019 by Sam Buchanan

[Sam Buchanan]

Just to close the loop....overall it's been a pretty good day for an old retired guy:

 

 

The manifolds survived in one piece, had to work them off a 1/16" at a time. Two long studs and three shorts need to be replaced, the other shorts look good. But I can look forward to drilling some studs and retapping holes.......

 

Does anyone have a source (with part numbers) for these studs or do I go ahead and pop $70 for a complete kit? I also have a stud extractor tool on the shopping list.

 

Thank you for the suggestions, sometimes input will stimulate the brain cells into finding a solution!

Edited October 2, 2019 by Sam Buchanan

[Plymouthy Adams]

remember, a number of these go into the water jackets...seal them on install....also you should be able to buy the studs a lot less than buying a set prepacked but again, your area like mine for the most part is pretty repressed.....I do have a good machine shop nearby that will order what I need and usually for fair price.  These should be pretty well stocked at a NAPA....

 

from what I can see you don't have much concern here....inspect the stud closely....many may not need anything above dressing with a nut die...I feel your biggest issue will be the bolts that hold the two manifolds together....renewing these I assure I would not even tackle without a few heat cycles with the torch and maybe a bit of candle wax to lube by capillary action.....ALSO....pay close attention to the special instruction on the two halves when reassembling and installing back onto the block..the procedure is easy but should never be overlooked...

[Bbdakota]

I figured it wouldn't be long before you tackled this job. I only had to replace the 2 long studs but at the time, it was a Friday and I wanted the car going by Saturday for a cruise in or something. I used grade 8 bolts, sealant on the threads and anti seize in the holes in the manifold. I increased the torque value slightly due to torquing against coarse threads in the block vs fine threads using nuts 

[Sam Buchanan]

5 minutes ago, Plymouthy Adams said:

remember, a number of these go into the water jackets...seal them on install....also you should be able to buy the studs a lot less than buying a set prepacked but again, your area like mine for the most part is pretty repressed.....I do have a good machine shop nearby that will order what I need and usually for fair price.  These should be pretty well stocked at a NAPA....

 

from what I can see you don't have much concern here....inspect the stud closely....many may not need anything above dressing with a nut die...I feel your biggest issue will be the bolts that hold the two manifolds together....renewing these I assure I would not even tackle without a few heat cycles with the torch and maybe a bit of candle wax to lube by capillary action.....ALSO....pay close attention to the special instruction on the two halves when reassembling and installing back onto the block..the procedure is easy but should never be overlooked...

 

I'm going a different direction with the heat riser situation. The exhaust manifold will get a blockoff plate that is bolted to the manifold, and the intake will be trimmed to allow clearance for the blockoff plate bolt heads. I don't want to ever have to deal with a blown gasket between manifolds and I'm not worried about losing the preheat. I will make new steel washers where two manifold ears are secured by hte same nut.

Edited October 2, 2019 by Sam Buchanan

[Sam Buchanan]

1 minute ago, Bbdakota said:

I figured it wouldn't be long before you tackled this job. I only had to replace the 2 long studs but at the time, it was a Friday and I wanted the car going by Saturday for a cruise in or something. I used grade 8 bolts, sealant on the threads and anti seize in the holes in the manifold. I increased the torque value slightly due to torquing against coarse threads in the block vs fine threads using nuts 

 

Now that is a fine idea!

[Bbdakota]

1 minute ago, Sam Buchanan said:

. The exhaust manifold with get a blockoff plate that is bolted to the manifold, and the intake will be trimmed to allow clearance for the blockoff plate bolt heads. I don't want to ever have to deal with a blown gasket between manifolds and I'm not worried about losing the preheat

I like the way you think!

[Sam Buchanan]

6 minutes ago, Plymouthy Adams said:

your area like mine for the most part is pretty repressed....

 

Repressed???? Madison, AL has the highest per capita ratio of engineers of any city in the country.........white collar welfare thanks to the incredible Huntsville economy! 

[Plymouthy Adams]

Been to Huntsville, many years ago....English car meet....left there to run to Nashville to grab a set of rare cast exhaust manifolds for my Sunbeam Tiger get rid of those stupid headers........many many moons ago when the water was still drinkable......and well...gas was still somewhat fairly priced...

 

we have the  mighty Robins AF base in my neck of the woods....they their own entity...self sustained for the most part...little need of the local economy for this type stuff....

Edited October 2, 2019 by Plymouthy Adams

[TodFitch]

2 hours ago, Sam Buchanan said:

Does anyone have a source (with part numbers) for these studs or do I go ahead and pop $70 for a complete kit?

 

Those are not highly stressed parts, the manifold stud nuts being brass and all. Worse comes to worse a stainless bolt from your local hardware store cut to length with some fine threads cut on it (I assume you have a set of dies) will work. At least that will work if you can find a bolt with a long enough unthreaded shank.

[Sniper]

soak 'em in kroil the night before you try to pull those studs out.

[Sam Buchanan]

I plan to put some heat on the block around the long studs with a torch prior to attempting to back them out (bought a stud extractor). But even if they come out one short stud is broken off even with the block. I'll try welding a nut to it before resorting to drilling and tapping.

Edited October 3, 2019 by Sam Buchanan