Technical Engine block exhaust manifold stud snapped

[torniojaws]

I cleaned the maniverter of my 2008 1.2 65 Grande Punto, and while reinstalling the maniverter, one of the engine block studs (where the gasket is fitted) snapped just before reaching the target torque (24 Nm, ~18 ft-lb). I tightened them in a X pattern, first to finger-tight, then ratchet resistance, and finally to torque.

They appear to be a part of the engine block - is there some way to replace them? At least they don't seem removable, unlike the headless bolts that you attach after fitting the maniverter in place. It's the one in the top left.


The maniverter is still attached by 7 of the 8 nuts and bolts, and no flames appear so it's not yet critical, but it's something I'd like to get sorted.

Thanks!

 

[chris3234]

You normally use a special tool called a stud extractor to remove things like that

 

[Rado77]

Hehe, this I solved few days ago - the same stud broke!!! I added pictures into thread named "Injector or valve clearance?". Its on pages 8 - 10. Things were complicated because after I driled hole into broken stud with 4 drill and tried to use removing tool, that tool broke inside! Finaly I had to use special pipe with diamond ring to drill it away. After that I drilled it with 8.5 drill and made new thread and used new stud size 10
Anyway - is 24Nm correct? What I saw was tightening of nuts two-step way: tight to 2Nm and then 30 degrees...maybe its equal to 24Nm...just to be sure...

 

[torniojaws]

Ah, I thought they are welded into the head I think there's still a piece sticking out of it, which I might be able to grab.

 

[chris3234]

Ah, I thought they are welded into the head I think there's still a piece sticking out of it, which I might be able to grab.

No they are normally just screwed into the head
Given yours have snapped you'd probably need to weld a not or something o to the end to remove the old one and our new ones it

However if you don't get any leaks you may be able to continue as you are

 

[Bernievarian]

Ah, I thought they are welded into the head I think there's still a piece sticking out of it, which I might be able to grab.

Don't waste your time by attempting more then once to grab it, if it doesn't work the first time it will probably never do. Get someone weld (MIG is perfect) a M8 nut on the protruding part and remove the broken strud from the head ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

 

[torniojaws]

Yeah, drove around today until the engine was at normal temperature, and then checked the idle engine after the drive. Still no leaks or flames, or oddities, so I guess it's fine for now.

 

[torniojaws]

Looking at the video clips I made, it has indeed snapped inside the head. The other end of the broken-off bolt has no threads, and no threads are visible from the head when it was attached (marked with a green arrow), so it is inside the head then.

Damn, if had known these were also detachable, I would've replaced them but, you gotta start somewhere

Anyone happen to know the size of the headless bolt for the Grande Punto, so I don't have to remove the maniverter until I'm ready to fix it? Looking at some similar ones, it appears one end is quite varying length across vehicles. For example one has 10-11 threads on one side (as does the broken-off one I have), but the other end has 14-15 threads, which could be the end that is inside the head.

Update:
Actually, I'm pretty sure it is the same size on both ends. The second attached image shows the bolts I removed and on them it appears the thread amount is the same on both ends. The end with no nut is from the head-side. The green measurements are from the broken-off bolt I have in my hand.

 

[Bernievarian]

Hi (who?) and welcome on board!

on an engineering point of view, it makes absolutely NO sense to have different thread diameter or pitch on such an assembling device...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

 

[torniojaws]

Anyway - is 24Nm correct? What I saw was tightening of nuts two-step way: tight to 2Nm and then 30 degrees...maybe its equal to 24Nm...just to be sure...

I checked a couple of other cars, just to compare, and it is in that ballpark for all:

BMW, 22 - 25 Nm
Mazda, 22 - 31 Nm
The older Punto, 25 Nm

Can't post links yet to the forum (5 posts needed).

 

[Bernievarian]

Here is the torque table ... note that the values are in DaNm where 1 DaNm = 1ish mKg (actually 0.981)

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)BRs, Bernie

 

[llamallama]

Just saw the pics

Couldn't you get some penetrating lubricant, spray soak a few times then get a pair of vice grips nice n tight on it then unscrew,
unless there isn't enough room for the grips,

 

[Pugglt Auld Jock]

Just saw the pics

Couldn't you get some penetrating lubricant, spray soak a few times then get a pair of vice grips nice n tight on it then unscrew,
unless there isn't enough room for the grips,

Over the years I've spent working as a mechanic and, latterly more as an enthusiast, a broken stud/bolt is one of the more annoying problems you will face. It can turn a relatively simple task into a bit of a nightmare can't it. Especially those smaller 6mm fixings you often find on inlet manifolds and heat shields on exhausts which are often difficult to access with a drill and so difficult to drill accurately as there's not much "meat" in the first place.

Of all the methods I've tried, welding a nut to the broken remains of the stud definitely works best by a long way. Unfortunately it means you need access to welding gear and that you are reasonably proficient at welding (it won't work if you don't get good weld penetration on the stud itself - It's easy, if you don't know what you're doing, to end up with a nut which looks brilliantly welded but is actually just sitting, stuck a bit like glue, on top of the stud with all the weld melted into the nut! When you apply a spanner it simply twists off the top of the stud without removing it) However if you do it right the combination of extreme heat and being able to get a real grip on the whole diameter of the stud means, I've found, that it comes out quite easily 99% of the times.

Now-a-days, if I run into this problem, The first thought that goes through my mind is: Can I get the MIG torch in there without having to dismantle anything else?

If you've never tried it, I would encourage you to give it a go. I've found it really liberating and lets you deal with this annoying problem far quicker than any other method I know. Of course it doesn't mean you're not occasionally going to run into one which just won't respond. In these cases I wouldn't waste time messing about and wasting time, just drill the whole thing out and install a Helicoil or Wurth insert - Or, if it's a bit you can get easily and cheaply at your local breakers, just swop it out?

 

[llamallama]

Indeed,

I actually have a very similar situation on an exhaust manifold right now,
Where the last of the seven nuts got rounded,
I can't get a small nut cracker in there nor vice grips,
Maybe a Dremel with a weee grinding disc could get at it,

 

[torniojaws]

Just saw the pics

Couldn't you get some penetrating lubricant, spray soak a few times then get a pair of vice grips nice n tight on it then unscrew,
unless there isn't enough room for the grips,

Well, that's the problem. There is nothing to grip, as it is actually about 1 - 1,5 mm inside the head.

But I bought some left-handed cobalt drill bits with some bolt extractors included, which I'll try as the Grande Punto does have a fair amount of room for a low height drill, and in my case the bolts aren't really "stuck" / rusted. Probably not enough space for a "regular" size drill though, and removing the front grill would put the screw at an angle. And an angle drill would probably just make a mess.

I also ordered some brand new headless bolts as a replacement. They were surprisingly hard to find, but if you also need some, you should find them with either of these product codes:

This is the OE number Fiat, Chrysler, Jeep, Alfa Romeo, Dodge, Lancia use (ie. the same bolt is used by all of them):
13588524

And I also found this other product code, but not sure where it comes from. It does give you the same bolt. It might be a manufacturer-specific product code:
985-835-825

With the second code, I found a little bit more sellers, so you might find a local dealer's store with it. I bought mine from Autodoc for 0,77 € (0,86 USD) per bolt (x8).

 

[llamallama]

the end of the bolt is only 1.5mm inside the head?
That doesn't seem like it has enough of the head to hold onto?

 

[Bernievarian]

Please All, use correct wording when talking about technicall parts !!

Screw: threaded rod with a head, which can have various shapes
Nut: usually hexagonal, it matches the screw's thread
Bolt: assembly of the two previous parts
Stud: "headless" screw

And BTW the OP talks about "cleaning the maniverter" That makes absolutely no sense, translated in French (my native language) it could be retranslated as "cleaning the handling" or "cleaning the way to manipulate things". Manifold is the correct name for that part.

BRs, (grumpy) Bernie

 

[torniojaws]

the end of the bolt is only 1.5mm inside the head?
That doesn't seem like it has enough of the head to hold onto?

What I meant is that the stud has broken so, that there is a "hole" of 1,5 mm in the head. The broken part of the stud probably has about 12-13 mm of it still inside the head. See the attached illustration.

And BTW the OP talks about "cleaning the maniverter" That makes absolutely no sense, translated in French (my native language) it could be retranslated as "cleaning the handling" or "cleaning the way to manipulate things". Manifold is the correct name for that part.

Well, it's is the word Fiat and many others uses for that part The combined manifold + catalytic converter. If it didn't have a built-in catalytic converter, then it's just an exhaust manifold.

 

[llamallama]

Ah yep, got ya

 

[llamallama]

I wouldn't worry about trying to get it out,
Just seal it up and that's it,
You would still be able to get the manifold off,