I bought a new Gates water pump for the Cambridge, pn 42544. Follow along as we look into it's quality. Externally, it looks decent, no obvious casting flaws. Though the design does change one mounting boss from the original, Gates includes a longer bolt to compensate. Bearing design is improved over the original as well

I took the backing plate off the pump to inspect the inside of the casting as well as the impeller. These are the backing plate bolts, the black stuff is casting sand, not good QA. The bolts are M6 metric ones, thread pitch 1.0. That is also a change from the original.

Looking inside the pump we see a nice cast impeller and no obvious casting flaws. I started draw filing the mating surface, the dark spots are the lows. We'll address this.

Here we see the mating surface all cleaned up. All backing plate bolt holes were cleaned out with a tap and then followed up with brake cleaner. All pipe thread holes, 3/8 NPT, were chased and cleaned up with brake cleaner. When final reassembly was done the backing plate bolts were put in with thread locker as a precaution. All pipe plugs were installed using teflon tape. Aside from the issues noted the pump was good from a mechanical inspection aspect.