exhaust manifold studs stripped - best way to remove?

[stickshift]

20yr old Toyota Camry - a couple of the exhaust manifold studs stripped while I was reinstalling the manifold.

Removal:
Weld a nut? Is there something I should try before welding and permanently deforming the threads? I don't think the good thread section is long enough to get 2 nuts on and jam nut the stud out. I guess there is some risk the threads in the aluminum head will get damaged when trying to turn the steel stud out?

Installing new studs:
I guess hope I can fit 2 nuts on? Where can I get thin nuts so I can use jam nut method to install the studs? Is there another method to install?

 

[Firebrick43]

Have you tried an E torx socket?

 

[Wrench97]

They have a E torx head on them for installation.
For removal I'd heat it up red hot quench it cold and see if you can wiggle it loose with a e torx socket, if not switch up to a screw extractor socket then if that doesn't work move on to welding a nut on it. Of course get the manifold out of way first.

 

[signcrafter]

Never had the threads strip on one when reinstalling the manifold. You can try an etorx socket first. In my experience if the stud is stuck in the head the etorx usually just snaps that part off. If it's not stuck it may come right out. After that I would try a stud extractor. If that doesn't work then it's on to the fun stuff. I usually go right to welding a nut, it heats up the stud to hopefully break any rust holding it tight and then comes out. But in your case the stud didn't snap off like I usually run into, the threads stripped where the nut goes somehow. Start simple and escalate as needed.

 

[stickshift]

The have a E torx head on them for installation.
For removal I'd heat it up red hot quench it cold and see if you can wiggle it loose with a e torx socket, if not switch up to a screw extractor socket then if that doesn't work move on to welding a nut on it. Of course get the manifold out of way first.

I've got a MAPP-Pro torch - so torch the head around the stud and then quench the stud? The torch won't warp the aluminum head?

 

[PCustoms]

I've got a MAPP-Pro torch - so torch the head around the stud and then quench the stud? The torch won't warp the aluminum head?

That torch won't heat that bolt red hot...

How/what is stripped?

 

[stickshift]

That torch won't heat that bolt red hot...

How/what is stripped?

See pic in OP. The exhaust manifold stud is stripped.

 

[stickshift]

Have you tried an E torx socket?

Didn't even know what that was until I read your post. So that's how these studs are installed. Man, that torx section is so short and narrow, seems like it would round or snap off with any resistance.

 

[PCustoms]

See pic in OP. The exhaust manifold stud is stripped.

I see it, like I saw it before..

I still can't understand your issues. Is the nut now stuck, and you're looking to get it off?

 

[alwaysFlOoReD]

I've got a MAPP-Pro torch - so torch the head around the stud and then quench the stud? The torch won't warp the aluminum head?

The way heating a bolt or stud works:
Once the part is heated to near red hot the stud wants to expand. The only direction it can go is longitudinal. When it shrinks back down the diameter is slightly less. This makes for less friction and easier removal. Map torch is unlikely to make it hot enough for enough expansion.

 

[Wrench97]

I've got a MAPP-Pro torch - so torch the head around the stud and then quench the stud? The torch won't warp the aluminum head?

Heat the stud not the head.
As asked above will the nut come off or not?

 

[dcg9381]

Weld a nut? Is there something I should try before welding and permanently deforming the threads? I don't think the good thread section is long enough to get 2 nuts on and jam nut the stud out. I guess there is some risk the threads in the aluminum head will get damaged when trying to turn the steel stud out?

Man, I'd weld that bolt on there all day long. The heat may help the stud come out when you turn it out. I'm not so much worried about stripping it as I am worried about breaking it. Stud looks deformed already, I'm thinking best bet is to get that out of the aluminum head. Heat helps... Break it, whole new problem... YMMV. Good luck.

 

[mm08822]

Also use a center punch on the end of the etorx. Several good hits and that can break the bolt free from rust. Then maybe some pbblaster can get worked in. Repeat.

 

[stickshift]

I see it, like I saw it before..

I still can't understand your issues. Is the nut now stuck, and you're looking to get it off?

No the nut is not stuck. I need to get the stud out of the head so I can replace it.

 

[PCustoms]

No the nut is not stuck. I need to get the stud out of the head so I can replace it.

Take the nut off and show us the stud.

What nut were you using?

There's a chance you can clean the threads and get a fresh nut...

 

[stickshift]

Man, I'd weld that bolt on there all day long. The heat may help the stud come out when you turn it out. I'm not so much worried about stripping it as I am worried about breaking it. Stud looks deformed already, I'm thinking best bet is to get that out of the aluminum head. Heat helps... Break it, whole new problem... YMMV. Good luck.

Yeah I'm thinking welding a nut on there may get more heat into the stud than my MAPP pro torch. But scared of snapping it and creating a bigger problem. Might have to call in a pro for this.

 

[stickshift]

Take the nut off and show us the stud.

What nut were you using?

There's a chance you can clean the threads and get a fresh nut...

I'll take a pic tomorrow but the metal that you're seeing removed and off to the side is from the stud, not from the nut. I don't think there's any hope of chasing the stud's threads and making them usable.

Nut was new Toyota OEM - M8 1.25 I think.

 

[PCustoms]

Nut was new Toyota OEM - M8 1.25 I think.

For future reference, anytime you've got nasty crusty hardware like that, clean all the **** off before threading it back together. I'm shocked the initial threads don't show wear...

This rule also applies to the exposed ends of threads prior to disassembly. Clean the crud off so it doesn't get halfway out and lock up

 

[stickshift]

For future reference, anytime you've got nasty crusty hardware like that, clean all the **** off before threading it back together. I'm shocked the initial threads don't show wear...

This rule also applies to the exposed ends of threads prior to disassembly. Clean the crud off so it doesn't get halfway out and lock up

Yeah, that's probably what happened. I did hit it quickly with a wire brush, but access all the way around the stud isn't great. Lesson learned.

 

[BillK]

Most Japanese studs come right out with the correct female Torx socket. I rarely have to do anything crazy to remove them. Get the socket and try tightening slightly and then loosening. I bet they will come right out. I use Deep Creep penetrating lube once I get them started.

 

[signcrafter]

I'll take a pic tomorrow but the metal that you're seeing removed and off to the side is from the stud, not from the nut. I don't think there's any hope of chasing the stud's threads and making them usable.

Nut was new Toyota OEM - M8 1.25 I think.

From your picture it looks like you were trying to put the nut on and it never tightened because the nut or stud threads stripped. Have you tried taking the stud out yet? It may or may not come out. I've never ran into your issue, usually it's that stud snaps off when I'm trying to take the nut off. I always replace studs when I take the manifold off. Think service data for most manufacturers say to replace. Try taking stud out and see what happens. Like I said before start simple and escalate as needed. If the threads stripped the stud needs to be replaced, there is no fixing correctly. They are cheap and most come out easily.

 

[Stuart in MN]

I can't tell from the photo, but would it be possible to run a die on the stud to clean up the existing threads well enough so they'll hold the nut?

 

[stickshift]

Update: So I fully removed the nuts and I was mistaken. @PCustoms was right to want to see the stud in full. And the guys who said they'd never seen exhaust studs strip like this were on the right track. It was the brand new Toyota OEM nuts, purchased from a local Toyota dealer. 3 of them stripped like they were helicoiled. All 3 of them wouldn't easily go on my thread restorer tap, but the other 2 did (and those 2 I was able to torque just about to spec (very close before I got suspicious about the other ones and stopped).

Going to order a thread restorer die and clean up those studs, just to be safe, and put the 20yr old nuts (ran through restorer tap) back on, because apparently the new stuff is ****.

Eh, sorry for the potato pic of one of those studs. I think all 3 will be fine after running restorer die over them.

 

[mm08822]

Sure they gave you the correct thread?

 

[stickshift]

Sure they gave you the correct thread?

Yes, I was able to get them all started by hand, and nearly had 2 of them to torque spec of 27ft-lbs (and those 2 easily went onto my M8x1.25 tap), so definitely the correct size. And they are exhaust manifold nuts with the wobbly captured washer (not sure what correct term is).

 

[PCustoms]

Sure they gave you the correct thread?

That's my thought as well. Something is off

 

[signcrafter]

Update: So I fully removed the nuts and I was mistaken. @PCustoms was right to want to see the stud in full. And the guys who said they'd never seen exhaust studs strip like this were on the right track. It was the brand new Toyota OEM nuts, purchased from a local Toyota dealer. 3 of them stripped like they were helicoiled. All 3 of them wouldn't easily go on my thread restorer tap, but the other 2 did (and those 2 I was able to torque just about to spec (very close before I got suspicious about the other ones and stopped).

Going to order a thread restorer die and clean up those studs, just to be safe, and put the 20yr old nuts (ran through restorer tap) back on, because apparently the new stuff is ****.

Eh, sorry for the potato pic of one of those studs. I think all 3 will be fine after running restorer die over them.

Something not making sense. Try the nuts that go on good on all the studs to make sure. But if the new nuts the right size and thread then they should go on. Not sure why 3 of them stripped the threads out.

 

[mm08822]

A 5/16-24 unf is verrrrrry close to M8-1.25.

Along with the stud's starting diameter taper, I could see these studs trying to cut modified threads in the nuts. Hence, the "heli-coil" throw-up.

Were the nuts from the dealer provided in a sealed package or loose?

Have Part number?

 

[signcrafter]

You can do what you want but at this point if it was me I would be seeing how easily the old studs come out. If they come out easy I would replace. Try an etorx socket and see if it comes out, worst case it's going to snap the torx head off the stud which has happened to me many times. If it does snap the torx head off then you can decide if you want to just use it or go to the effort of removing.

Something isn't right if the threads are coming out like that. Just guessing you may be right the new nuts are not good/right. But something isn't right, the only issue I've ever had is the stud breaking off when trying to remove.

 

[BillK]

Yes, I was able to get them all started by hand, and nearly had 2 of them to torque spec of 27ft-lbs (and those 2 easily went onto my M8x1.25 tap), so definitely the correct size. And they are exhaust manifold nuts with the wobbly captured washer (not sure what correct term is).

27 ft lbs sounds waaaaay too high for those studs. 8mm x 1.25 bolts and studs are typically around 12-14 ft lbs. I generally use my 1/4" drive oz-inch wrench to torque them. They are one of the most common size bolts and studs used in engines that I work on all day.

I just looked it up in my engine builders software and it does say 27 ft lbs but I would bet money that is a mistake. I wonder if it is supposed to be in Newton Meters ??

Post the vin or exactly which engine it is and I will try to find out more.

 

[67King]

Absolute worse case scenario....after using heat and a penetrant with an E-Torx socket. Stack washers on the stud, and torque it down where the threads are still intact.

27 ft lbs sounds waaaaay too high for those studs.

Class 10.9 M8's have a 26 lb-ft torque spec.

 

[stickshift]

27 ft lbs sounds waaaaay too high for those studs. 8mm x 1.25 bolts and studs are typically around 12-14 ft lbs. I generally use my 1/4" drive oz-inch wrench to torque them. They are one of the most common size bolts and studs used in engines that I work on all day.

I just looked it up in my engine builders software and it does say 27 ft lbs but I would bet money that is a mistake. I wonder if it is supposed to be in Newton Meters ??

Post the vin or exactly which engine it is and I will try to find out more.

Toyota 2AZ-FE engine. 27 ft-lbs or 37 Newton meters. This is what Toyota publishes (screenshot from Toyota service manual, not third party manual). I agree, it does seem like a lot for a small diameter stud and does make me nervous given that snapping a stud here would create a lot of extra work (if it was somewhere where I know welding a nut can easily get me out of a jam, I'd be a lot more cavalier about it). I may go a few ft-lbs lighter, say 22, and see if that's sufficient to seal off the exhaust.

 

[Blk88GT]

I've done broken exhaust manifold stud extraction by mig welding nuts on to the leftovers with great success.

 

[john.k]

I once torqued a row of 3/8 unc bolts on a Caterpillar head to 100 ft lbs ,like the rest of the 1/2 bolts .......none of them broke or stripped ,and I redid them to 30 ft lbs ......of course they were Caterpillar bolts.

 

[dcg9381]

I once torqued a row of 3/8 unc bolts on a Caterpillar head to 100 ft lbs ,like the rest of the 1/2 bolts .

Aluminum head to 100 ft/lbs? These are always a bit of a pain. Especially if older. Once you snap one flush, it's a problem. Assuming the studs are in the heads correctly (or can be replaced), I've been using copper lock nuts on similar vehicles. Copper will give up before the stud will and they don't back off.

 

[BillK]

Toyota 2AZ-FE engine. 27 ft-lbs or 37 Newton meters. This is what Toyota publishes (screenshot from Toyota service manual, not third party manual). I agree, it does seem like a lot for a small diameter stud and does make me nervous given that snapping a stud here would create a lot of extra work (if it was somewhere where I know welding a nut can easily get me out of a jam, I'd be a lot more cavalier about it). I may go a few ft-lbs lighter, say 22, and see if that's sufficient to seal off the exhaust.

I just looked up the spec for a GM 5.3 and a Chrysler 5.7 and they are 16 and 18 ft lbs respectively.

 

[stickshift]

A 5/16-24 unf is verrrrrry close to M8-1.25.

Along with the stud's starting diameter taper, I could see these studs trying to cut modified threads in the nuts. Hence, the "heli-coil" throw-up.

Were the nuts from the dealer provided in a sealed package or loose?

Have Part number?

Why would a Toyota dealership's parts dept have 5/16-24? Practically everything on Toyotas apart from spark plugs are metric. They were loose, not in a package.

Pic of nuts - new ones from dealer on left (top two didn't strip, bottom 3 did strip), factory originals on the right. They look like the same design to me. Maybe more chinesium in the modern ones compared to the ones from a couple of decades ago.

 

[mm08822]

Why would a Toyota dealership's parts dept have 5/16-24? Practically everything on Toyotas apart from spark plugs are metric. They were loose, not in a package.

Pic of nuts - new ones from dealer on left (top two didn't strip, bottom 3 did strip), factory originals on the right. They look like the same design to me. Maybe more chinesium in the modern ones compared to the ones from a couple of decades ago.

What they are and what they should have been could be 2 different things. It could be no fault of the dealership, dunno. It's a guess.

My point is, they are almost identical and to the assuming user, they "are" the same. Then hits the fan as you lived it .

 

[bbxlr8]

FWIW Found myself in similar situations and added Kroil penetrating oil to my arsenal of heat/shock/welding as a last resort. Not cheap, but got me out of some nasty predicaments. Some also swear by 50/50 acetone/ATF

no affiliation... https://www.kroil.com/product/kroil-original-penetrant/

 

[Firebrick43]

I doubt a cat diesel or natural gas engine has an aluminum head