Fixed Cooling Flaps

When VW changed their thermostatic control system, and moved from a ring that restricted flow into the fan shroud, to flaps inside the fan shroud, those flaps actually served two purposes.

 

The first purpose, was to provide for rapid warm up.  When the thermostat is closed, the flaps are closed, and restricts the airflow, and mostly restricts the airflow from the top of the cylinders and the fins of the cylinder heads.  As the temperature under the cylinders increases, and the thermostat starts to open, those flaps open and start allowing more airflow.  Once the thermostat fully opens, the flaps are aimed directly at the top of the cylinders, and the cylinder head fins and opening in the exhaust port sides of the heads.  Because the airflow coming through the fan shroud swirls, the flaps serve a second purpose.

 

The second purpose is to straighten the airflow out of the shroud, since it swirls to some degree inside, and make sure that the majority of the airflow goes to the most critical areas of the engine, which are the very tops of the cylinders (they have the largest fins because this is were the majority of the heat is that is not in the cylinder head), the cylinder head fins, and the exhaust port side openings of the cylinder heads.  The later on the cylinder heads is the most important area, and isn't restricted by the flaps at all, even when the thermostat is completely closed.

 

With that technical background, if you build an engine without a thermostat, and without the thermostatically controlled flaps, you are actually not getting the best possible airflow to the most critically areas of the engine for cooling.  Also, aftermarket fan shrouds, for the most part, don't even have the holes for the screws that are needed to install the flaps.  

 

So, if you don't want to run the thermostat, or cannot because of your exhaust system, and you either have an aftermarket fan shroud, or just don't have flaps, you need this product to get the cooling system at it's optimum.

For OEM fan shrouds, these fixed cooling flaps simply mount exactly as the original thermostatically controlled cooling flaps.  You just need the eight cooling tin screws (same as the screws used for all the other cooling tin), and put the fixed cooling flaps in the fan shroud, with the correct ones on each side.  With the thermostatically controlled flaps, there is no way to install them incorrectly, because of the control mechanism.  Since these don't have that, it might be a little confusing which one goes on which side.  Having said that, they are easy to tell apart.  The one that installs on the 1/2 cylinder side of the engine, the right side when looking at the engine installed, has three deflectors and the side profile is large until the after the second mounting nut, where is quickly descends to where the third and lowest deflector is.  The one that installs on the 3/4 cylinder side has three main deflectors, and one final one on the end that caps off the end on the inside of the engine, and it has a large dip in the side where the mounting nuts are in the middle.

For aftermarket fan shrouds that do not have the screw holes for the flaps, you need to modify the fan shroud to add the screw holes so the flaps can be added.  Besides the screw holes, the aftermarket fan shroud also have sheet metal below the fan, just like the OEM, but the dimensions are longer, and it interferes with the 1/2 cylinder side flaps.

Provided in the kit, are five templates for locating the screw holes.  The first four are for the screw holes, with the fifth being for the aforementioned sheet metal that has to be trimmed back under the fan on the 1/2 cylinder side.

Two of the templates, the longest two are for the 3/4 cylinder side of the engine (left of the engine when looking at the engine installed).  They are the same in terms of where the screw holes are, but the one for the alternator/generator side of the fan shroud is slightly longer, and for the inlet side of the fan shroud, it's shorter, because the sheet metal stick out on the end, and that is where the fan shroud is joined together.  This keeps the holes aligned on each side of the fan shroud.

The 1/2 cylinder side has the same thing, where the one for the inlet side of the fan shroud is shorter, but it also has some reliefs cut into it because of the overlap of the area of the fan shroud where the inlet is, and the part of the fan shroud that captures the air and redirects it to the offset oil cooler.

The last template aligns with the edge of the sheet metal directly under the fan on the 1/2 cylinder side, and you can scribe, or use a marker to mark where to trim back that sheet metal.

What you will need to use the templates.

• Automatic punch.
• Some kind of clamp (a pair of vise grips will work).
• Drill with a 2.5 mm drill bit, and a 7 mm drill bit.
• Metal scribe or marker.
• Tin snips, or very small reciprocating saw, or a dremel, or other small cutting tool.

Using the templates is fairly straight forward, but a little tricky.  Take the correct template, and align on both on the outer edge of the fan shroud (right side is the 1/2 cylinder side, and left side is the 3/4 cylinder side), and also push it up against the curved raised area that sits just above the cylinder tin.  Make sure you don't allow the template to side up that curved raised surface, and make sure on the alternator/generator side that you have it aligned all the way to the flat of the outside of the fan shroud.  When you have it aligned, carefully clamp it in place.  One the inlet side the outer edge will just sit directly against the sheet metal.  It's much easier to align.

Remember when you clamp it in place, it will have a tendency to move from it's position, and you can easily damage the template if you clamp it too tight.  So, just double check, or even triple check your alignment.  Once you drill the hole, there is no going back!

Once you have verified alignment, and have it clamped in place, use the automatic punch, in the two holes, to indent the fan shroud for the center of the holes to be drilled.

Once you have the indentations from the punch, you can drill the holes.

Starting with a 2.5 mm drill bit, which is easier to make sure is centered on the identation, which will be quite small, and is also easier to make sure it doesn't walk off the center point, drill through the shroud, without impacting the other side of the shroud.

Once the 2.5 mm holes are in place, you can then switch to the 7 mm drill bit and enlarge the holes to 7 mm.  Remember, don't allow the drill bit to hit and go through the other side of the shroud.  You have the other templates to get those holes in place.

After you have the screw holes drilled, you can use the marking from the trim template, triming back the sheet metal under the fan, and cut out the sheet metal up to the scribed or marked line.

Once that sheet metal is trimmed back, you can install the fixed cooling flaps just like in the OEM fan shroud!

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