Fit a new V8 coolant pump

Fitting a new coolant pump is a common and fairly simple task, and it gives the opportunity for some extra maintenance. Ed Evans explains

A common and simple task that allows the opportunity for extra maintenance

Ametallic growling noise in the engine bay is not what you expect to hear from a newly rebuilt V8. So it was a relief to see a steady drip of liquid coming from the coolant pump gland on the front of the engine, which suggested the pump was the source of the noise. The coolant pump’s bearings and seals sit next to each other on the pump shaft so, when the bearings wear with age, they allow the shaft to move slightly which, in turn, distorts the seals allowing coolant to drip out. An engine rebuild doesn’t include the front cover and coolant pump so, before fitting these, we’d carefully checked the pump for bearing condition, and it seemed fine at the time. Given the low cost, we should have fitted a new coolant pump as a matter of course, and I’m not sure why we didn’t – probably so excited at the new engine and with so many other aspects of the car’s rebuild occupying our minds that it got overlooked. Not cool. The upshot is that it’s not a particularly onerous task to fit a new one.

Some care is needed when removing and refitting the securing bolts to avoid shearing them and/or damaging threads, and it’s worth cleaning the threads and shanks of the bolts before refitting.

The first job, as always, was to drain the coolant after first confirming the engine and coolant were fully cooled, and carefully releasing the header tank cap to confirm there was no residual pressure. In this case we drained the coolant by releasing the radiator bottom hose and collecting it into a clean plastic container placed beneath, controlling the flow by refitting and releasing the header tank cap to allow air in.

The viscous fan (if fitted) will need to be removed from the front of the coolant pump, though not on this engine which is cooled by separately mounted electric fans.