17yrsWith930

My Carrera 3.2 is 30 years old (1985) with the original exhaust heat exchangers. Do I need to be concerned with corrosion letting exhaust into the cabin as you needed to be concerned with a late 60's or early 70's 911?
Or, are they made of stainless steel for these cars?
Thanks for your help !

theiceman

I am not sure if they are stainless or not , but I can tell you its just not an issue. My SC exchangers just about rusted right off but the headers underneath are rock solid . I think the tinwork on the exchangers are several orders of magnitude thinner than the exhaust. In fact after I let the rest of the heater box fall off I think I will paint up the headers and sell them

17yrsWith930

Thanks theiceman !
If anyone else has more information on the question, I would appreciate it.
When I got my '71 it was a big deal, at that time in the mid-eighties.
It doesn't seem like anyone is talking about getting exhaust gasses into the cabin now.

theiceman

I think you will always get some fumes in the cabin, just not enough to be any type of issue. its not like its so air tight no fresh air gets in.

I do have a funny story about this though ,..

My son was about 7 at the time and he was wondering exactly the same thing and he came up with a plan .. I thought it was so cute I went along with it ..

he wanted to take our home carbon monoxide detector in the car and check it ... it had a battery backup so he thought it would work.

so off we go down the street and he has the CO detector in his hands .. he fires open the air vents and doesn't the thing go off ...

Im sure most of you can imagine what it like to have that thing go off in a tiny compartment like a 911 . it was excruciating , he freaked out and dropped t , I had to yell it him to shut it off coz he could not hear me .. the battery however was in the thing and the cover was screwed down .. I kept yelling at him to shut it off as I thought my ear drums were going to bust . he thought of a great idea and wound down the window and threw it out ...

My last views of my 75 dollar carbon monoxide detector was in smashing into pieces behind us as I viewed it in my rear view mirror..

oh well ....

off to Home depot to get another before we go home to mom and have to explain it.

EMBPilot

$4
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17yrsWith930

I don't buy it.
If I was buying a car in 1985, and I got "wind" that the Porsches have some exhaust leaks into the cabin, I would not buy one and I'd be on the way to the Mercedes dealership.
Cute story though.


Seriously, no one can tell me the differences (material, manufacturing process, design philosophy, anything) between a heat exchanger from a '71 911 to an '85 911?

theiceman

they are the same principle .. whether you buy it or not doesn't really matter, as it is what it is .. .. if its that big an issue sell your car and move on ..

17yrsWith930

theiceman,
I think we are deviating from the original question.
Your first answer was helpful, thank you for that, but I am trying to get more factual information to make a decision from.
My car does not have fumes in the cabin, at least none I can tell (and I know carbon monoxide is colorless and odorless, I believe).
I do not intend on selling my car. I just bought it. I keep cars a long time.
I've had a 930 for 17 years (hence my "handle") and my first car for 37 years (always in running condition).

So, I'm just trying to figure out, that since my heat exchangers are 30 years old, and I intend on keeping the car for a long time, does it make sense to replace them since I am doing some exhaust work on the car. Or, did Porsche make design and material changes to the heat exchangers from 1971 to 1985 that makes this issue a moot point and the heat exchangers are now bullet proof???

John@Fabspeed

Hello!

I saw this thread and wanted to drop by and offer some insight into the heat exchanger/header design on the air cooled Porsches.

To start, it is going to be extremely difficult to find the detailed information requested in this thread, and many props to those who may find it! Information on manufacturing design and materials is unfortunately very proprietary to vehicle manufacturers, especially concerning a design flaw in the 70s and 80s that would more than likely have been a "hush hush" design change. We see these subtle design changes done in today's vehicles as well, and they are rarely advertised unless brought to light by outside sources. A prime example would be GM's recent recall campaign. As hard as to is to say, many vehicle manufacturers operate roughly the same way. They make changes as they go and let the earlier design fly, at least until they decide it's become a big enough problem to warrant the costs involved to making it public and issue a recall. That being said, most companies are not ignorant and won't wait as long as GM to act on major recalls. GM is under a magnifying glass now, which is why we have seen such a substantial number of recalls from them lately that may otherwise have been a subtle design change.

Getting back on track, here is what we do know about the heat exchanger design on the air cooled 911s. Porsche has costs to consider for mass production, and in doing so they don't use the best metals available to manufacture their factory exhaust systems, and the factory manifolds/heat exchangers are no exception. Ferrari for example does the same thing and the factory headers on the F355, F360, and especially the F430 are absolutely horrific and in some cases have caused engine damage on the F360 and F430.

In the 20+ years we have been upgrading the exhaust systems of the air cooled Porsches, we have seen the factory heat exchanges falling off the manifolds, and we have seen the manifolds under the heat exchangers with pin holes, cracks or clearly broken and in the rare occasion even with the heat exchangers in seemingly good shape. The earlier the vehicle, generally the more common we have seen these issues. With the exhaust escaping the manifolds and being collected and channelled by the heat exchangers towards the cabin, yes there is a possibility you may be exposed to some exhaust fumes. That being said, we have also seen them in absolutely mint condition with no issues at all. It all depends on how it was driven and in what weather conditions.

For those concerned about the common heat exchanger issues, we offer an RSR Header/Muffler Kit. This kit includes headers/heat exchangers crafted of the finest T304L stainless steel and TIG welded to perfection. We fabricate them, and all of our exhaust components to outlast the life of your vehicle, and in doing so they come with our lifetime limited warranty (just don't go 90mph over a speed bump or get rear ended). Of course we improved the design as well to offer better performance and sound to match the quality

Please feel free to PM me with any questions on our products, and of course I will do my best to answer any questions about factory issues components as well

Amber Gramps

Who drives with their windows up anyway? If it's raining, park it. If it's sunny, open the poor thing up. You are driving a freakin' air cooled German road oiler....of course there is smoke in the cabin.

17yrsWith930

Fabspeed,
Thanks for your comments. I appreciate it. I will be contacting you soon ... I'm very interested in the Sport Cat and I will get your input on other items.


As for you amber lamps,
There is no smoke in the cabin of my current car. I don't have and will never have again a "road oiler" Porsche. Y'know, these are (or were in some cases) high quality cars with demanding customers that would not put up with "road oiling" and smoke in the cabin (except for their cigar smoke). You probably don't mind that your convertible top leaks water too.
The only road oiler I've had was my '71 S, so I got rid of that one for $10k. What do you think I am, not smart???

Amber Gramps

My cab has spent a grand total of one night out in the rain. We booked the wrong hotel...it didn't leak a drop. And I gave away the one and only FabSpeed part I will ever purchase.

John@Fabspeed

No problem, and I look forward to working with you to make it sing

Steve Weiner-Rennsport Systems

Your Carrera has stainless-steel HE's and unless they have been damaged or suffered heavy exposure to salt, do not have the same longevity issues as the older mild-steel units used on the sixties and early-seventies cars.

I would be careful about being talked into something you really don't need.

17yrsWith930

Thank you Steve.
That is very helpful.