Diagnosing a failing pump
There are a couple of ways to spot problems with a water pump, besides the obvious gasket leaks.
First, use your ears. Bearings on their way out will start to whine, or even grumble. Any unusual noise warrants a further check. The way to do that, is to use your hands on the pulley shaft and feel for any side-to-side play. It should be tight, but rotate smoothly. Any wiggling in the shaft, or rough spots when rotated, mean it’s time for a new pump.
Unbolt with caution
1 Choose a water pump fixing with good access. With a well-fitting spanner or socket on it, force is applied. Hopefully, we feel it come free and rotate.
Moment of dread
2 With a crack, this fixing shears in half just at the end of the threaded section. Will they all do the same? Only one way to find out…
Avoiding the snap
3 Sometimes, a little heat can help. Using an oxyacetylene torch, James carefully applies heat to the head of a fixing for 30 seconds, then tries to undo it.
Four out of eight
4 Using this technique, four of the eight fixings come out in one piece. However, the other four shear. We now have to extract those from the engine block.
Where to start?
5 The four broken bolts have barely a thread or two standing proud of the engine block. It can look daunting, but there’s a way to get them out.
Make it a bolt
6 James deftly Tig-welds a nut onto the stump of the fixing. A spot-weld first attaches it, then he fills in the nut centre with weld for extra strength.
Voila!
7 The finished job. Effectively, the remains of the sheared fixing now becomes a bolt. The nut doesn’t even need to be squarely attached, just welded with good penetration.
Will it come out?
8 James uses an impact driver, thinking a little extra shock may help coax it out. With a few measured taps from the gun, the fixing spins straight out.
Result
9 This is the result. Because it threaded out cleanly, there’s no further damage or swarf in the engine block, unlike using a drill, which needs great care.
Engine face
10 Now, there’s just one remaining stud to remove, then the gasket face will be carefully cleaned and, if necessary, flattened before fitting the new pump.
Gasket is important
11 With all the sheared studs out without further issue and a clean mating face, we’re ready to fit the replacement parts. First, a quality gasket goes on.
Old and new
12 The old pump and the new replacement. It sounds basic, but check the new part is correct. I always check the mounting hole positions are identical before fitting.
New seal
13 Now is the time to change any other minor seals around the pump. Here, we fit a new rubber O-seal for the water pump/ thermostat housing joint.
On it goes
14 The new pump is offered into position. I don’t use sealant because any that comes loose internally can clog a heater (usually the smallest passages in the system).
Fix it in place
15 New bolts are used, with lock washers, and torqued up. Note, there may be varying bolt lengths around the pump. These are BSF thread, being a Series I.
Anything else?
16 Connect any surrounding feed pipes such as this water pump inlet pipe, which has its own gasket. We fit a new one of those and use new fixings.
Important part
17 Especially on SI, check the fan for cracks – a fan shattering can take a radiator out. Satisfied, refit the fan, pulley and belt. Don’t over-tighten the belt.
Hoses
18 Consider the condition of coolant hoses and belts. Replace any remotely suspect, and don’t forget the heater feed pipes, too. On a Series I they are copper pipes.
Fill her up
19 Refill the system with the right mixture of antifreeze to water. Check the refilling instruction for your car; some fill through the radiator, some through the coolant reservoir.
Moment of truth
20 Having bled the system, start the engine (heater set to maximum), run to operating temperature, switch off and check for leaks. If happy, road test briefly and re-check.