Heat exchanger removal

[Dpmulvan]

Working on removing my heat exchangers and every bolt is locked up nice. My 8mm allen seems a little loose as does my 13mm socket for the nuts. I have already stripped one and don't want to strip anymore. I have applied heat with a propane torch but I'm afraid it's not hot enough. I'm assuming I need acetylene. Any thoughts or tricks would be appreciated.

[boyt911sc]

If you have the engine off the car or an engine stand, try to soak and lubricate the nuts with penetrating oil. But with the car installed it is quite awkward. I use an impact wrench at moderate setting and have no problems removing these stubborn exhaust nuts. Try to use a 13-mm 6-point socket because it holds the nut/fastener better. Consider using a Mapp gas which is much hotter than the propane gas. Keep us posted.

Tony

[Trackrash]

There is a place in heII for "mechanics" who don't use anti-seize on these exhaust studs.

[SCadaddle]

The method I've seen on numerous occasions is to heat the barrel nuts with an acetylene torch until they are cherry red then immediately insert the allen socket on an extension through the access holes in the heat exchanger and give it a FIRM whack with a hammer then apply the ratchet and start turning it off quickly before it cools down.
Seen it done this way with the engine on a stand or simply the top end torn down to the point of the heat exchanger still attached to a bank of 3 heads.
What you do not want to do during reassembly is to have the engine on the stand upside down to install the heat exchangers allowing for crud to fall out of the exchanger into the heads of your freshly rebuilt engine!

[Dpmulvan]

going to get acetylene torch today, I think mapp gas only burns a few hundred degrees more than propane. Engine is on a stand and bolts have been soaking for over a week.

[911pcars]

Suggest conducting a thread search on the topic. There are other, more "exhaustive" and helpful discussions on how to successfully remove HE nuts and studs.

For now, fasteners heated red hot are more malleable than when cold. Applying torque to a red hot nut (internal or external hex) will distort the gripping surfaces. Use heat to expand relative parts; use a penetrating oil to break up the corrosion; use heat/cold cycles to break the bond between parts and allow penetrating oils between parts.

This is a former barrel nut after several heat cycles and applications of Kroil. After the internal hex was distorted, a slot was cut along the length of the barrel nut using a Dremel cutoff disk. This allowed a long HD screwdriver acting as a lever to increase the nut ID to loosen its grip and to unthread the barrel nut from the still-intact stud.


I would apply the above penetrant to your exhaust studs. Wire wheel if you can access it, then cover with a layer of anti-seize to prevent further corrosion - for future disasembly.

Sherwood

[tharbert]

^^This is how I got a few of my more stubborn exhaust nuts off^^^ Probably got the idea from Sherwood in the first place...

[Dpmulvan]

That's how I got the first two off (carving with a dremel). I have worked on cars and motorcycles all my life and have never had such a headache removing bolts. I feel sorry for the guy trying to remove these on the car.

[Luccia at Pelican Parts]

Typically, to access the heat exchanger barrel nuts, you will need to have an angled 13mm wrench and a special heat exchanger barrel nut removal tool. If you are using the correct tool and it's more so an issue with the nuts being extremely too tight, soaking the nuts with something may also help.

May I suggest possibly visiting this tech article? If you do not find it helpful, posting in the comments section will allow for a technician to offer their input as well, which may help solve your issue even further. Pelican Technical Article: Replacing Heat Exchangers - 911 (1965-89) - 930 Turbo (1975-89)

[Dpmulvan]

I have all the right tools,soaked everything for days,read every article I could,and used heat. I managed to get the right side off only broke one stud and had to dremel the nuts off.I appreciate everyone's input. Now my battle continues on the left side.

[gtc]

The acetylene torch method really does work well. You'll wonder why you didn't just do it to begin with.
The whack with the hammer isn't really necessary, from my experience.

[Dpmulvan]

I did use acetylene and finally finished up today god what a pain in the ass!! On to the next battle thanks for the input people appreciate it!!

[SCadaddle]

I'd suggest the FIRM whack with the hammer does 2 things:

1) Gets the fasteners' attention.....hey buddy, you're fixing* to come off!
B) Imprints a shape of the allen tool in the hot, malleable barrel nut for a better grip.

* "Fixing"......same as "about" south of the Mason Dixon Line and fully accepted as "proper speech".

[luyckxglen]

Im curious in how rusted these bolts where?
Since i've been in this hell aswell.. only to remove the cat-
pictures below.. i had to cut and destroy the cat to gain access to the bolts. THen torched it and used a dremel cutdisk , trying to punsh it true but in the end even that did not work..
now the bolts on my exhaust are as rusted .. So i can imagine if i ever want to remove this the studs could brake if i have grip. And else if there is no grip at all how do you remove it

[Dpmulvan]

I couldn't imagine trying to do that with the motor in the car.

[911pcars]

Drop the drivetrain. Access with torch, Kroil, motivational tools with patience will be easier, perhaps enough to offset the potential cost to EDM broken HE studs. Go to archives to see several examples of attempts, some successful, some not. Yes. Sometimes nuts remain fused to studs.

[Dpmulvan]

Well How did you make out ? Any luck