DDK - Die Deutschen Klassiker

my '67 912 seems to have 'export' heaters on as it came from California, basically instead of a heat exchanger in the conventional sense of the word, there are just J tubes in a pressed steel jacket, so the only heat absorbed is off the one pipe as opposed to the fins of a heat exchanger. Are 'real' heat exchangers readily available? and what do they cost?

Your best bet is to check over the existing system to make sure its operating as it should.

If the J-tube heat exchangers are structurally sound and not rotten, then check the flapper boxes to ensure they're also in good shape. Its important to ensure the flaps on the flapper boxes and the hot air valves mounted on the car itself, all fully close when you pull the heater lever to on.

Also important to check the condition of the ducting hose which leads from the top of the heat exchanger to the hot air valve.

When setup correctly, you'll be amazed how well the system works. Honest!

As far as I'm aware the export exchangers are no longer available - Plus, fitment to a car fitted with export heaters is a serious job. You need to change the main engine fan housing, heater cables and guides etc....

Hope that helps!
Max

Also check you have no exhaust leaks as this will mean Carbon Monoxide will enter the cabin with deadly results. Halfords sell cheap detectors, worth the few pounds that could save your life. As Max says a sorted system will literally roast your socks off, especially if you leave your foot nest to the outlet.

Cheers both.

All of the components look to be in pretty good order, but I think a couple of the 4 cables could do with a bit of tweaking, and the flexible hoses are past their best, so need to be replaced, but the heater boxes/J tubes are in very good nick. I'll have a play about, and probably manage to get it all fully soprted in time for our blistering summer thats long overdue!!

Evil J Guano wrote:Also check you have no exhaust leaks as this will mean Carbon Monoxide will enter the cabin with deadly results.

I'm pretty sure i get this in the cabin of my car cos i can always smell fumes / fuel smell when the heating is "On". To prevent me unknowingly nodding off at the wheel i only keep the lever open when its really cold and only then in small amounts and keep a couple of windows open for fresh air. Its really not very pleasan tho. Whats the best way to deal with this issue?

Evil J Guano wrote:As Max says a sorted system will literally roast your socks off, especially if you leave your foot nest to the outlet.

Totally agree. Mine works great and can really toast your feet if you're not careful!

Whats the best way to deal with this issue?

Not the nicest job in the Porsche world I'm afraid. You need to find the leak, most likely where the exhaust is attached to head, gaskets sometimes leak, or you may just have a hole in the J Tube. Both involve taking off the Exhaust system, something which could involve a days work under the car trying to get off the seized studs... better than dying I guess

I would buy a Carbon Monoxide tester from Halfords run engine with heater open and windows shut (driver OUTSIDE car) and see if it is a leak first.

Petrol fumes are a different matter and might be a whole other expensive matter if you have a leak... see here for possible consequences...
http://www.912register.co.uk/enginefires.html

Sorry not a bundle of joy these things