engine cooling

[Bret]

I have a 1974 1.8 litre 914. The engine cooling flaps have been removed. All sheet metal and ductwork are in good shape. Is this a problem? This is my first Porsche.

[Ian Cubus]

I am assuming you are talking about the flaps that the thermostat controls. Me and a friend run a VW shop here in N.C. and he and others I have seen including myself until recently have never reinstalled the flaps back into the fan housing after rebuilding engines. I have never seen first hand anything negative come about however if you leave the flaps out you lose the purposeful directing of cooling air over the oil cooler which in the long run will shorten engine life. The arm that supports the flaps has a spring attached where the thermostat connects that forces the flap to direct air over the oil cooler. Also those control flaps when coupled with the thermostat allows the engine to warm up fast and maintain temperature. It's your choice but I run the flaps with the spring because I want cooler oil. Hope this helps, Ian

[macman]

i once heard from someone, that if it was originaly on the car from the factory, it probably needs to be on ther now in order for the engine to cool properly.

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Michael Scheid
(206) 232-9854

[Dave at Pelican Parts]

Ian, no offense but your friend has fallen prey to one of the major VW myths. The flaps should be there. Always. Without them, the air does not flow into the correct places.

On a Type IV, one of the flaps ducts cooling air down through the oil cooler. If the flap is not there, the air will flow over the top of the cooler, making a low-pressure area. This will suck air up through the cooler--air that is coming off the heat exchangers. HOT air. Not real good for cooling.

The cooling system was specifically designed to have all of its pieces in place. Without some of them, too much air will go to some parts and not enough will go to others. You'll get hot and cold spots, which are bad for the engine's lifespan. Sometimes you can get away with this in a Bug because those motors are not very stressed. It's pretty rare that a 914 motor will let you get away with it for too long...

Some people take the thermostat off and let the spring on the cross-shaft keep the flaps open all the time. I think it's best to have the t-stat there as well; it helps the engine get up to operating temps quicker. This is good for the engine life.

--DD

[Ian Cubus]

Dave I agree with you. I guess I wasn't clear enough in my reply. I do run the cooling flaps because I know what they do but I just haven't seen an engine fail without them.

[Ascaris]

Or, is he talking about the two rubber flaps attached to the bottom of the firewall in later models to help with the air circulation?