I'm confused about how the 914-4 thermostat and cooling work. I don't have a thermostat on my engine and I'm trying to figure out how this thing works. When I look at the 2 flaps that the thermostat controls, they seem to be in opposite positions from where I thought they would be. Without the thermostat or its wire connected:

o The drivers side flap is all the way up, seemingly open to let air pass over the cyclinders. Is this the position for maximum cooling?

o At the same time, the passenger side flap is is closed on the oil cooler, not letting any air over the oil cooler. This seems to be a position for cold engine operation, just the opposite of what I would have expected given the position of the driver side flap.

Question: does the thermostat get longer or shorter when heated? This has got to be one of the most unique cooling systems I've ever seen.

Please help

Spoke

The little bellows thermostat is compressed when cold pulling the wire and the flaps down. As it heats up, it expands and opens the flaps. Pretty simple and works great for the colder climates as to get the motor to operating temp fast.
When fully open it also directs cooling air over the oil cooler.

Geoff

Yes, when one flap is "up", the other should be "down" On the oil cooler side, even when the flap is down there's a big enough gap on the hinge end of the flap too allow enough air to the oil cooler. Much more air is needed for the heads, and cylinders than for the oil cooler.

The bellows should be fully compressed at room temp, and will expand as it is heated, thus opening the flaps, one up, one down. bellow is under a slight vacuum, such that if it springs a leak, it will full expand, and keep you flaps in the cool positon

be sure you replace all rubber seals to prevent air leakage. besure all holes are pluged, sparkplug holes, oil press. switch hole, head temp hole, and then also make sure all your engine tin to body rubber seals are good, else your fan will suck inhot air from under car.

A nice thing to add is a VW Bus (type IV) fan screen. It is plastic domed screem that screws onto existing tapped holes in the fan housing. Helps keep leaves, and rags from getting sucked in.

Also be sure you the rubber air duct between the fan housing, and the alternator is good. This is needed for cooling the alternator. And if missing, just bleeds needed cooling air thru a pretty good sized hole.

Aslo never remove the flaps, even if the bellow is inoperative. If the bellows fails, it fails safe, with the flaps in cooling position, you will take longer to warm up with the bellows dead, but if you remove the flaps the air flow will be messed up, the oil cooler would be wide open, and either be a loss of cooling air, or maybe if the air speed is fast enough, actually venturi hot air from the cooler, not sure which, but you want the flaps there working or not.

That should get your cooling system up to snuff.

good luck