Propan torch on a mag case
 

Hi Everyone,

I have security questions concerning propan torch on mag case.

In 2016, I rebuild my engine after a piston failure. Of course, I had leaks on the numer 8 bearing.

I rebuild it after 4000 km.. and still have this leak.

So I decided to use Tom amon's solution. Of course, it started to leak after a thousand kilometer.

My question is : How can I use safely without bruning my car (and also my house) a propan torch in order to remove (and reinstall it)?

By the way, now in france we have a new control... if they saw a leak, they can immobilize your car...

Thanks everyone http://forums.pelicanparts.com/uploa...1522050248.JPG

I would cut a circular hole of the correct diameter in a piece of fireproof sheet and wedge it in place so that only the steel sleeve is exposed. An assistant can spray the case behind the fireproof sheet with water to avoid any unwanted heating.

(An air-only torch will burn at around 1,995 °C (3,623 °F), Magnesium is flammable, burning at a temperature of approximately 2500 K (2200 °C, 4000 °F), and the auto-ignition temperature of magnesium is approximately 744 K (473 °C, 883 °F) in air.)

I would worry more about oil on the engine catching fire rather than the magnesium....
The case is a pretty large heat sink, plenty of people have used a propane torch on a mag case.

Igniting a small bit of magnesium:
https://www.youtube.com/watch?v=mLt0cToM_vw

i remember when doing my brothers engine that there was a rubber Oring on the bearing.
it wore a groove in the case. if yours did the same thing and you did not machine the case I doubt you will ever fix the leak.

I really doubt a propane torch is going to ignite a MAG case.

We hit the mag cases with map gas to remove head studs. No way will propane hurt the mag. Be careful of all the other things that heat can damage.

Thanks à lot for your helps guys

@Porboynz : that was exactly what I had in mind. I will put some aluminium sheat all over the place to protect everything.

@T77911S : you are absolutly rigth as you can see on the picture below...

Maybe a solution to stop the leak is to tear down the engine and use some threebond around the oring.

I think I did lots of mistake when I rebuilt this engine. I put some helicoil with 993 head stud... I also have a seepage on a case through bolt... and some around rockers arms...

Unfortunatly, every time you speak about tearing down a 911 engine, it costs at least few hundred $ and possible mistake that can definitly break your engine for good!http://forums.pelicanparts.com/uploa...1522167624.JPG

I would ask him for advice on the removal process.

Should this be done without splitting the case for example ?

I already asked him and he told me to use a propan torch. Be before playing with fire, I prefire double check to make sure I didn't miss something...

Besides the magnesium catching fire, I would also worry about the other stuff melting around that nose bearing and making a mess.

MB911 knows mag way better than I do but I do know you won’t ignite a mag case with a propane torch. At least not easily. We hit the mag case for 2-3 minutes with map gas to release the studs. I’ve seen 911 engine fires melt the induction on an engine but only discolor the case. I would follow Tom’s advice.

I'll defer to the experts but ... propane torches are reportedly used to cut steel in some industries.

Even without melting, the heat can soften the case material. It's your case so do what you want with it. I would be very careful here.

What's the purpose of adding heat? Is it just to drive thermal expansion to make separation of parts easier? If so, you might consider using an electric heat gun (usually good to ~600F).

Heat gun aint got nothing on a torch. I would imagine the heat gun would take to long and the heat would spread to surrounding areas instead of the local point you want the expansion to take place. Your not heating it up hot enough to burn it anyways. Other stuff will burn before the mag lights up. Purple K is your friend.

you should ask someone like JW or others with more engine rebuild experience about the groove and how to fix it.
flat6pac would be another one to ask, maybe even tony. I know he has done a few rebuilds
PM them

if the parts are new you are just looking at a gasket set.
if the case needs to be line board then you need new bearings, of course the nose on will eat your lunch.
rockers could be how you installed them.

Thanks, I will defninitly PM them

For what it's look like to me, I won't torch my case -> too risky. I will wait until the next tearing down. As they said on this thread; it's easier to remove when you disassemble it.

The case doesn't need to be line board because it was already done (see picture).
For the rockers, I suspect that the camshaft housing wasn't in good shape; Maybe I will have to install the RSR oring.





http://forums.pelicanparts.com/uploa...1522239391.JPG

Propeylene is what people are thinking of cutting steel. Propane will not.. You will just fine for a couple of minutes with propane or mapp.. The heat dissipation is so rapid on the case as long as its torqued you are fine..

Ok thanks, I'll keep you in touch as soon as I'll do it.

Have a nice day

For what it's worth the sleeve fix did hold up so far for my #8 nose bearing leak and it's been two years. I almost killed the engine in the process as you can see here: http://forums.pelicanparts.com/porsche-911-technical-forum/908678-attempted-leak-fix-3-6-ends-disaster-need-comlete-teardown-argh-2.html

But that's another story altogether. Maybe you didn't clean the area well enough or didn't get enough epoxy or something? I'll keep my fingers crossed and good luck to you.

Ingo

Hi,

Thanks for sharing your experience. Here is the picture of the installation.

I think the problem could be the magnesum which probably "moves" more than alluminium.

Also maybe I didn't install-il or screw it enogth. As long as it's not an exact science, it's hard to say it.

http://forums.pelicanparts.com/uploa...1522411939.JPG
http://forums.pelicanparts.com/uploa...1522411939.JPG

By the way,

If you ask why I was forced to rebuild my engine... here is te response...
http://forums.pelicanparts.com/uploa...1522413203.JPG