1990 Mazda RX-7 13B Water Pump Housing Repair
The second generation of Mazda's RX-7 saw it turn from a focused sports car to a slightly larger GT car. It was the first time the car was offered as a convertible, such as the example being looked at here.
The car arrived with complaints of a broken water pump housing where the thermostat housing bolts to it, that was leading to cooling leaks and over heating. One of the bolts that attaches the thermostat housing to the water pump housing had been over tightened at some point, which broke a piece out of the housing. This left no way for the bolt to thread in properly. Since the thermostat housing couldn't be tightened down, coolant would leak out and lead to the over heating.
The housing is a major part of the cooling system that helps route the coolant from the engine itself to the water pump, thermostat, and main coolant hoses that go to the radiator. Since it's pretty easy to tell what's wrong in this situation it's time to get right into the repair. Click on the pictures in the gallery for details.
The car arrived with complaints of a broken water pump housing where the thermostat housing bolts to it, that was leading to cooling leaks and over heating. One of the bolts that attaches the thermostat housing to the water pump housing had been over tightened at some point, which broke a piece out of the housing. This left no way for the bolt to thread in properly. Since the thermostat housing couldn't be tightened down, coolant would leak out and lead to the over heating.
The housing is a major part of the cooling system that helps route the coolant from the engine itself to the water pump, thermostat, and main coolant hoses that go to the radiator. Since it's pretty easy to tell what's wrong in this situation it's time to get right into the repair. Click on the pictures in the gallery for details.
Unfortunately we forgot to get pictures of the broken housing (sometimes it's hard to remember to grab pictures when you're working and you're hands are pretty dirty.) The owner had actually provided another used housing, but we elected to use the original. While the old housing was damaged, it was damaged at a bolt hole that could be welded back up and then re-threaded. The other housing showed signs of internal corrosion and pitting at important areas like where the water pump mounts. That type of corrosion can lessen water pump efficiency and lead to pin hole leaks in the housing that are sometimes hard to track down.
A close up of the alternate water pump housing looking into where the water pump mounts to it.
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The beveled surface is what the impeller on the water pump spins next to, to create suction and move the coolant around. The pitting you see can cause drag, reduce pump pressure, and can also lead to pin hole leaks in the housing itself.
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The car is all together, so it's time for the moment of truth. The video also shows a little bit more about the water pump housing.