Type 3 Exchangers
Posted: Thu Dec 18, 2008 2:50 pm
Amskeptic wrote:Excellent. I'll bite.The Air-Cooled Ranch wrote: The Type3 heat exchangers in their factory form and on the '68s and '69s I owned in my mispent youth DID come with outboard insulation as well as some metal plates held on with a sort of metal "zip-tie".
I thimk that if Foxtail wants to indulge in such factory-inspired improvements, the trick to pulling it off successfully would be to apply some manner of "sealant" to the insulation - POR-15 perhaps? - in order to retain some semblance of "water-proofing".
I have a Type 3 that rudely burnt my bananas to a crisp and overheated the interior with ease last winter without any of the insulation wrap left.
The heat output of the Type 3 engines was so startlingly effective that they had to use "mixing valves" supplied with fresh air from the fan housing to cool the air down (that is what those metal pipes and paper hoses are doing traversing the tins just above the valve covers). They used bellows thermosts (like the engine thermostat) in both heater pipes at the body junction. The overheated exchanger air/fan housing air was supposed to moderate the temperature at cruise by opening those bellows ad allowing the fresh air in but close at idle and on long downhills where the exhaust pipes were going to be cooler. Type 3 engines were known to run a tad hot with that intense packaging of the cooler and low-profile cylinder covers. They were also known for very short exhaust valve life. S'its in the books. . . .
There is no way to waterproof the exhangers. They have rolled-edge seams that will not keep out moisture now matter how carefully you apply the wrap. Once water gets in, it is now trapped in. The closest modern equivalence to the wrapped exchanger jackets on the Type 3s are the wrapped U-pipes on the '75 and later buses. They have a fierce reputation for rusting out. At the time of manufacture of the Type 3, accelerated rusting out of the exchangers only matched the accelerated rusting out of the car itself, I don't think VW was too worried about the long term life of that set-up with all that manufacturing capacity to sell replacement exchangers. We, however, want this stuff to last.
Rejoinders welcome. Any Type 3 oem exchanger owners here? Any experience with the mixing valves?
Colin