For the record, this is my second replacement on my 2001 Saab 9-3 with almost 70,000 km mileage. This particular one failed right before the holidays.
First of all, here is the failed valve (made by Topran):
As shown in the picture, the bottom part of the valve, which consists of a L-shaped tube, broke off at the seam. Now, this damage condition shown here is actually terminal. Back when the valve was still installed in the car, although coolant was seeping from the seam, that bottom part still adhered to the whole valve body. It broke off during disassembly.
Driven by curiosity, I thought it would be interesting to dissect the valve and see how it works. Lets begin...
Upon disengaging the 6 plastic clips, the top is off.
The valve is vacuum-operated, so the top has a small hole where the vacuum pipe attaches to. When there is no suction, a metal spring pushes the diaphragm down. In this position, coolant flows from the top pipe on one side to the middle pipe on the other side. When suction is applied (through a solenoid valve), the diaphragm is sucked up towards the top. In this position, coolant flows from the bottom pipe on one side to the middle pipe.
A bronze rod connects the diaphragm to a rubber seal that partitions and switches the flow of coolant. The diaphragm is a hard plastic disk with a thick rubber seal around it.
With all the movable parts (the actuator) gone, one can see the hole that the bronze rod goes through. A tight rubber seal (damaged during the dissection) keeps coolant away from the diaphragm.
This is the passageway of the coolant. The rubber seal that partitions and switches the flow of coolant is held in place by enlarging the end of the rod.
Another shot at the damage before moving on to the replacement.
The replacement is made by Febi Bilstein of Germany.
Here is another shot, with the Febi Bilstein part number.
I wonder how long this new valve lasts. The Topran lasted almost 2 years.
The installation went well, as it was just a matter of connecting 3 coolant hoses and 1 vacuum hose. The coolant was a slightly different matter. Since it took quite a while for me to order the new valve, a considerable amount of coolant leaked out of the system. Whenever there is too little coolant (the Saab Information Display will issue an alert), I would add distilled water into the coolant recovery tank to top-up.
With the new valve installed, and that I have already added plenty of distilled water into the system, I thought this would be a great opportunity to do a "drain and fill" procedure. The "fill" part consists of using the famous Valvoline Zerex G-05 coolant:
This coolant is supposedly the same formula as Mercedes-Benz uses in its line of sedans, and is highly praised by many Saab owners. The jug I got is old stock, as I believe current version of this product is in a white jug. The content is the same - an apple-juice-color fluid.
