So quite a few weeks back I purchased a bunch of random air-cooled parts from Euroworks Garage to set aside as spares or to complete the various engine cases.
One item was a complete doghouse fan shroud from 71 or 72 that still had a complete set of flaps, oil cooler tins on the rear, and an undamaged emissions canister port.
Now as I understand it, a lot of people just would throw the flaps away and I’d have to say that from the engines I’ve looked at, as well as some I’ve purchased, this is in fact true. Most had missing flaps.
The flaps actually are tied to the thermostat that is supposed to reside down under the Cylinder 1-2 push rod tubes. There’s a thing metal rod on the thermostat that connections up between the cylinders and attaches to these flaps.
The entire purpose of this assembly is for cold climates. The flaps would remain closed at start, redirecting the air out the shroud, allowing the engine to warm up and reach full operating temperature faster. As the engine block would heat, the wax in the thermostat melts, pushing the rod upwards and this in turn moves the flaps to an open position in which they can now force air down over the cylinders and the base of the heads for engine cooling.
Of course, in warm climates, this is not really something needed so people just removed them and threw them out.
Heck, even the aftermarket fan shrouds you can buy do not accommodate the installation of flaps and these were also never available in the aftermarket.
Now the future performance engine I’d like to build is spec’d to use a Concept-1 aftermarket shroud, but these are not like the cheap China-made ones from EMPI or even SCAT. These are duplicates of the Mexican Beetle shrouds that incorporate larger Type 4 oil coolers and, the thing I love, they made allowance for the flaps to be installed! This is the kind of aftermarket part one has to drool over a bit!
So while the this shroud I bought will be a spare, I will restore these flaps and they will become the flaps of the future performance engine.
That’ll leave me a spare set from the AH engine to restore and have on hand as well. Murbella’s are still on her and will be inspected and possibly cleaned up and repainted during her engine refresh.
There is a lot of corrosion on the bottom of this fan shroud so getting the screws out was quite a challenge. 2 came out ok but the rest required quite a bit of heat but they all eventually broke and unscrewed.
The small clamps on the crossbar linkage and the flap linkage may be salvageable, but I’d really like to find some new ones or at least an equivalent style if these are not made.
With the flaps removed, and knowing all of the small pieces that should be on the cylinder tins (the air vanes) as well as the small cylinder head tins (where the thermostat rod goes up through) you can appreciate the simplicity of the system. It is completely mechanical, simple, and other than an issue with the thermostat itself failing (they are all 40+ years old now) it is about as brainless as you can get.
Now I’ve have people telling me fear stories of the their engines overheating because of the flaps not opening at operating temp, and of course, I suspect this is the fear mongering that went along with the “throw them away” mentality.
But I suspect that a properly functional maintained set of flaps with a proper function thermostat (original style of those used later on the Mexican Beetles) allows for a better running engine in the long term. Especially for a daily driver stock engine which is exactly what VW engineers were designing for all those decades ago.
I’m unlikely to bother restoring the assembly bolts and nuts, but I think this will be a simple winter project. Of course, it is too cold during the winter to do external spray painting so I may as well just do the clean up and prep work to finish it off in Spring and put them away until needed.
Now there’s a guy north of me here in Ohio who does business as Awesome Powdercoat and is one of these great, critical small vendors who focuses on elements of the air-cooleds as they pertain to the cooling system.
He makes a lot of custom products that VW created, but the aftermarket as a whole never cared too much about so I have to give him mad props for that.
He makes custom fan venturi rings to be welded onto 74 and older shrouds. These are integrated into the 75 and later FI fan shrouds.
He makes the internal cylinder tins air vanes that help the air flow around the cylinder heads. None of the aftermarket tins have them.
He even produces the small internal deflectors for the heads themselves that should come with every set of heads but don’t! (I was shocked the AE engine out of Żuczek had its still intact!)
He has even produced a series of tin installation videos on YouTube!