is a torch the key to NOT breaking exhaust bolts

[tomcat27]

how do you avoid breaking exhaust manifold bolts? heat them up cherry red and them wrench them? some other trick? this question is regarding two different cases:
1) removing bolts from cast iron heads (especially really old ones!)
2) replacing the exhaust manifold donut gasket from my Echo. most DIY'ers seem to break the bolts off and have to pull the manifold and re-thread...

 

[oldhp]

Use PB Blaster first, soak it at least 24hrs, if still stuck, use heat,ice trick. Heat up the manifold flange where bolts are threaded in, not the bolt itself. Heat it up and apply ice to the bolt, if possible.

 

[Dyusik]

I used pb blaster alone, with some back and forth motion after a good soak. Worked like a charm.

 

[Rick in PA]

We use to use the torch the nut to cherry red procedure at the service station I worked at long ago. It always worked. The nut would spin right off, no matter how rusty. You did have to avoid stepping on the nut once it fell to the floor, or it would melt into the sole of your work boot.

 

[Snoman002]

I recently had to remove some rusty exhaust manifold bolts on my G8.

PB Blaster was the key. I hit them with the PB Blaster and fairly lightly with an impact, they didn't come off. Tried PB Blaster and some heat, still no movement. Finally after about 24 hours, with I think 3 attempts involving a handheld propane torch and a cheap impact they just spun off like they were brand new.

A propane torch is almost worthless for getting a rusty nut off, but it can heat a rusty bolt enough to draw PB Blaster into the threads. Let the PB Blaster do its work, just keep soaking the part until it spins off.

 

[EdwardC]

You mention cast iron heads in particular, would it be a different process for bolts in an aluminum head? I have some stuck exhaust bolts on my motorcycle. I've sprayed them for weeks now, and even hit them with a propane torch, but no luck. I'm wondering if I should switch to something hotter.

 

[bradepb]

The torch or "liquid wrench" is used often to avoid breaking things or not being able to get it apart. You have to think about what you are heating and any damage it could cause.

Heating Aluminum is usually not a good idea, it will take very little heat then all of a sudden it melts..... I have done it but use very little heat, no way your going to get it red hot. An impact wrench could be tried on motorcycle heads with some caution. You have to just kind of rattle them or "shock" them loose, not just wail on them full force.

 

[Trav]

Originally Posted By: bradepb
The torch or "liquid wrench" is used often to avoid breaking things or not being able to get it apart. You have to think about what you are heating and any damage it could cause.

Heating Aluminum is usually not a good idea, it will take very little heat then all of a sudden it melts..... I have done it but use very little heat, no way your going to get it red hot. An impact wrench could be tried on motorcycle heads with some caution. You have to just kind of rattle them or "shock" them loose, not just wail on them full force.


I would add to that..Get the engine up to normal operating temperature, the aluminum expands greater than the steel bolts making them easier to rattle out. Use a small cordless 3/8 gun and let it rattle them out not full power where it will probably twist them off.

 

[JC1]

+1 on spraying all nuts and studs with penetrating fluid a day or two before repair. I usually spray them three times before if possible for a couple of days. You may also need heat depending on how much rust they have on them. Use a wire brush also to remove the top layers of rust.

 

[cat843]

Keep in mind that the bolts/nuts/studs have stretched with time and heat and are no longer the nice grade 5 they were when new. Heat and PB Blaster will surely help. Assume at least one will snap and a new nut or bold will need to be welded on to continue the removal process.

 

[Lapham3]

Good advice above-penetrents-heat-impact vibration

 

[The_Eric]

Manifold bolts can be a little trickier than studs. On an iron head, you can get a torch on the area by the bolt hole and give it some heat. Getting too carried away means you've burnt your valve cover gasket or other nearby items. On aluminum headed engines, you can try what Trav suggested.

For exhaust studs- nothing has ever worked better or faster than a torch. Period. (Unless you're rich enough to afford a Mini-Ductor)

IMO all the people calling for judicious amount of penetrant haven't done enough exhaust work. Sure, sometimes you get lucky, but after having gone down that road I've found that it just doesn't work well enough to even bother with. Also- I'm sure as heck not going to start soaking them several days in advance. I don't have time to do that.

 

[DriveHard]

Wire brush any exposed threads
PB blaster
wait
impact

That combo seems to have the best luck in my history.

 

[Rust_Belt_Pete]

Apply kroil, drive it for a day, repeat the procedure several times.

 

[John_Conrad]

for stubborn or rusty bolts I use acetylene torch to get hot and then impact them out.

that having been said, i once bought an exhaust manifold for a '78 chevy truck at a salvage yard and the parts guy said he would have to pull it off the engine as i waited, he came back with the manifold real quick, so i asked him how he got that off so quick and he said torch and wax.

i replaced that manifold on my truck with no problem, i was lucky that my bolts were not frozen and the impact got them out.

 

[Jetronic]

Originally Posted By: tomcat27
how do you avoid breaking exhaust manifold bolts? heat them up cherry red and them wrench them? some other trick? this question is regarding two different cases:
1) removing bolts from cast iron heads (especially really old ones!)
2) replacing the exhaust manifold donut gasket from my Echo. most DIY'ers seem to break the bolts off and have to pull the manifold and re-thread...


get some copper grease in them BEFORE they're that far gone.

 

[Trav]

If the exhaust manifold to pipe nuts where the donut is has plenty of access you can use a nut splitter on the nut then use a die to clean the threads up.
On nuts you can use a dremel reinforced cutting wheel to cut through one side of the nut almost all the way through, it will come loose easy then. you can make a diagonal cut also if space is limited.

The hydraulic ones are best, i use one similar to this (same brand), the regular screw type will work okay

http://www.ebay.ie/itm/Sykes-Pickavant-H...s-/400906504492

 

[dailydriver]

Originally Posted By: The_Eric
For exhaust studs- nothing has ever worked better or faster than a torch. Period. (Unless you're rich enough to afford a Mini-Ductor)


Yes it is really amazing just how much they can charge for some coiled wire with a cord and plug attached to it.

But, they DO work, as the place I used to take my car for exhaust work used them to great effect.