Type 3 Exchangers

Fastback, Squareback, Notchback, T-3 Karmann Ghia.

Moderators: Amskeptic, Sluggo

Post Reply
User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Type 3 Exchangers

Post by Amskeptic » Thu Dec 18, 2008 2:50 pm

Amskeptic wrote:
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".
Excellent. I'll bite.

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
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Post by Amskeptic » Fri Dec 19, 2008 7:53 pm

The Air-Cooled Ranch wrote: Isn't yours a '73?
It is. Original exhaust system.
The Air-Cooled Ranch wrote: I brought up the subject of the heat exchanger wrap as a possible heating system improvement for the pre-'72 buses since there was a factory precedent for insulating the outside of the exchanger. And it's kinda funny if you think about it - IF wrapping the heat exchanger made the durn things SO frikkin' efficient (and hot), why did VW go to the trouble of then adding on all the extra goo-gaws (the extra toobs, thermostats, and stuff/junk = $$$) to the mixer boxes?
Because they were trying to modulate the output temp under all conditions. So they designed the system to have bountiful heat at idle and downhill, and then they had to "blow off" the excess at load and speed.
The Air-Cooled Ranch wrote: The only ones I saw up close/personal were a '63 Variant N (my Dad's - a 15 year DD), a '64 Notch S, a '64 Variant (my sister's post-HS DD), a '65 Variant S (w/sunroof and later converted to IRS and 914 2.0L power - 10 year DD), a '66 Squareback (my other sister's), a '67 Fastback (parts car), a '67 Squareback (my brother's, a 15 year DD - purchased from the OO), a '68 Squareback (converted to a Baja in the early '70s - complete with Splitty RGB trans), and a '69 Squareback (20+ year DD). Bought, repaired and sold a few in the early '80s, plus wrenched on friend's (and my ex-sister/father-in-law's) Type3s during the same timeframe - long before the interwebs. I 'spose you could say I know a little bit about the care/feeding of Type3s.
Well, clearly then, you are new to these fine cars. See, I have owned 2, take off you shoes if you have to count higher, Squarebacks, one I owned in 1977 for eight months, and this new one, a '73, I have owned for two years. This new one hasn't broken anything yet at 54,000 miles, still has original VW brake shoes, and I can't tell you what the mixing valve t-stat temps/thread pitches are yet, because the original heating system is too damn functional still. . .
The Air-Cooled Ranch wrote: Funny you mention the thing about 'em running hot and having problems with burning valves - with all those combined years experience that wasn't an issue for the Type3s myself or my family has owned. Keep the intake air and the air-cleaner inlet secured to the bodywork ducts - they didn't have issues. Let the intake air boot get lost or strayed and you have BIG problems RIGHT now. In fact, of ALL those vehicles listed - the only one that I am aware of that ever burned a valve was the '69.


I have not had any hot running issues either. But we are merely optimal anecdotal evidence. If VW was recommending mandatory exhaust valve replacement at 30K if you took the heads off, well, they though they had an issue. My left cylinder head had a problem straight from the factory, a soft valve seat at #3. After measuring the VW exhaust valve for stretch or necking, I stuck it back in. I run cool. I make sure. But most of these cars grunged up pretty quick. And with a Type 3 pancake, there aren't many places for the crap under the tins to go.
The Air-Cooled Ranch wrote: Bonus points if you can tell me the opening temperature marked on the mixer box thermostat AND the thread pitch. Double secret EXTRA bonus points if you can tell if this makes 'em suitable as replacements for the dear departed Type4 thermostats :geek: I have two of 'em right here at the computer desk (they came out of the '65 S when it got T4 power), so the ball is RIGHT back atcha, chief...
75-85C and 1.25 that's my final answer, wait! can I call a friend?
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

Post Reply