Erik N

After reading about this in other forums, I'm think I'm gonna try it in my '92 MBZ. If it works, I'm gonna do it in the Suburbanator that still lives in Cali, and may even do it in the Green Machine.

Anyone have any firsthand experience w/ this?

Flame on!

AO

I believe it was Louie Ott that set his 928 on fire doing this. BE CAREFUL!

SteveG

Well, you didn't read about it in this forum b/c it has been discussed several times. You may already have a leak or you wouldn't be researching this. Putting something flammable in a suspect system is NOT a good idea. Where is that picture of Ott's burning shark? Might give new meaning to your words "flame on."

Cosmo Kramer

Have it completely vacuumed out, put in new oil and recharge it with R134. I did this on mine last year, didn't change anything else and the air is still ice cold even after it sat all winter. Cost me $60.

Erik N

The MBZ I was going to do it in has a relatively intact system. The last R-12 lasted about 1-1/2 years in there.
And apparently R-12 is flammable too. Don't know the flashpoint, though. I'll look it up and compare w/ R290 (propane).

[EDIT] OK the MSDS for R-290 says flashpoint is -156*F; Autoignition is 842*F.
R-12 flashpoint is N/A per DOT regs; Autoignition *F unknown.

The propane would be mixed with the R-12 already in the system, which would alter those figures by an unknown amount.

depami

Why not us anhydrous ammonia? It boils at -28 F.

It is not flammable but if you breathe enough of it, it will kill you.

dimmer

There are some companies that make propane based substitutes for R12. The most popular is Duracool. There are actually some benefits to using this: It is more "green" and performs better as a refrigerant.
In any case, I would suggest doing your research and addressing any leaks as a first step.

dprantl

Propane is definitely more flammable than R12/R134a. You should try using a mixture of propane and iso-butane. I believe that is what they are using in some parts of Australia where it is so hot that R134a cannot work adequately.

Dan
'91 928GT S/C 475hp/460lb.ft

Alan

Hah! I have a backpacking stove that uses that mixture - burns really really well - nice hot flame

Alan

dr bob

Just refill it with R-12.

JHowell37

You should probably try it. You're going to do it regardless of the risks of filling your system with flammable gas anyway. So have at it. We need to become a more open minded forum. Our slogan should be "yes you can" instead of "no you can't."

dprantl

Just to play devil's advocate here, gasoline also burns very well and some of those fuel lines are pretty darn close to 800 deg F exhaust manifolds Although it does run at about 3 -4 times less pressure.

Dan
'91 928GT S/C 475hp/460lb.ft

WallyP

Reasons to not put propane in the system:
- It is highly flammable.
- It ensures that virtually no commercial A/C shop will touch the car. If you "forget" to tell them that the system has propane in it and they contaminate their recovery system, you are responsible for the cost of decontamination.
- It gives you a compound refrigerant, whose constituents leak at different rates, so you will never know exactly what is in the system.
- It is more expensive - R-134a is $7 a can, Duracool is $11.

Reasons to use propane:
- It is easier.

Your car - your choice.

DR

Yep, the Professor of 928 Stroker Power, Big Round 928 Butts, and flaming 928 AC systems...among many other great 928 things (excluding the flaming AC deal as "great" , unless you have marshmallows). :-)

joejoe

I gonna jump in with suggesting auotfrost.