Method: Water pump repair. Feb 3, 2016 16:37:22 GMT
Post by Penguin45 on Feb 3, 2016 16:37:22 GMT
At one level, this is a slightly pointless exercise. The "B" series 'Crabs use the GWP130 pump, which is still freely available due it's use in the MGB. However, these are all alloy-bodied reproduction parts sourced from China and India, so whilst the prices are reasonable (£20 - £35), the quality is variable, thus the service life may be disappointing. This pump is the cast iron original from the Red Dog, so in the interests of preservation and history, I had a go at repairing it.
What goes wrong?
Obvious really – leaks and noise. The seal can fail and water starts to escape. The bearing can wear with age, but it is more likely that a weep of water will wash the grease out of the bearing assembly, causing rapid wear. Therefore, to refurbish the pump we need to replace the bearing and seal.
How to rebuild it.
The pump is an extremely simple machine. The pulley and impellor are pressed onto the bearing shaft and the bearing itself is located in the body of the pump by a soft iron wire.
Start by teasing out the locking wire. Locate the opening on the underside of the pump, shoot plenty of penetrating fluid in and allow it some time for it to work.
Use a combination of screwdrivers and pliers to pull out the locking wire. Next, use a gear puller to draw off the pulley.
Drive the shaft, bearing and impellor through the body. I tapped it through using a copper mallet – a better practice would be to use a press.
You now have an empty casing. This is the point at which it needs to be thoroughly cleaned inside and out, and painted if you wish.
Use the gear puller again to draw the impellor off the bearing shaft.
Shaft disassembled, revealing the water seal and the sealing face of the impellor. Clean it very carefully with thinners. You may need to use some very fine wet and dry paper to remove slight pitting.
Note the overall length of the bearing shaft, compared with the one removed. You need to match the shaft length.
Shaft trimmed to length. Note that a hacksaw will not even mark the surface of the shaft and attempting to part it off on a lathe failed. It had to be cut with a slitting disc in an angle grinder and then faced off on the bench grinder.
Reassembly, as Mr Haynes didn’t say, is not the reverse of disassembly.
Press the bearing into the body of the pump and re-fit the locking wire.
Press the pulley home.
Fit the water seal. I used a smear of Loctite 5922 around the base flange on the belt, braces and watertight principle. Ensure that it is pressed fully home.
Press the impellor back onto the shaft.
This operation requires a degree of precision, as the impellor will compress the seal. Set the gap under the impellor to 0.020”.
That’s it. When fitted and run for the first time, it is quite likely that the seal will leak briefly as it has to bed in against the sealing face of the impellor, so don’t panic.
The bearing is KG p/no 885158 and is a stock line from SIMPLY BEARINGS. It cost £10.32 plus VAT. The seal is Payen p/no W158 or NB037 (They are the same) and is in stock from M. BARNWELL SERVICES. It cost £5.50 plus VAT.
Like I said, pointless from a cost point of view, but an interesting technical exercise. Don't even think of trying it if you don't have access to a hydraulic press.