When nearing the completion of the engine of TA 0844 I was faced with what to do about restoring the waterpump. I had heard of certain modifications which incorporated modern internals but could find no details. Any advice I had received pointed towards having it professionally restored. I then decided on an “as original” restoration using the best components of two pumps acquired over the years. I will have to make a few parts.
Disassembly
The drawing shows the complete pump including the flip top oil pot or oiler. Very early pumps were fitted with a Stauffer greaser using hub grease, this was changed at engine number MPJG 1018 to a flip top oiler using engine oil. Photo A left shows the components of the pump from the impellor to the oilite bush and A right those from the internal circlip to the front.
photo A
It should be noted that there is a pin through the shaft which drives the graphite seal on the impellor side of the rear oilite bearing. Because of this pin the shaft cannot be pressed out from the rear. A circlip, which holds the front bearing grease seal, is located around the shaft at about one third of its length from the front. The shaft cannot be pressed out from the front unless this is removed. Removing the circlip is not an easy task. If the circlip is removed pressing the shaft out from the front will push out the oilite bush because of the shoulder on the shaft. Try the following procedure first:
Remove the splitpin, castle nut washer, pulley and woodruff key. Clean the rust and old gasket material from the backing plate to reveal two countersunk screws which hold it to the body. The screws were removed by soaking and much persuasion, and both backing plates were badly corroded and were unusable. Set into the back of the pump body is a circular donut, shaped on its inside to complement the impellor shape and having a lip on its outer edge. This lip fits a groove in the body. The donut is an easy fit and will only be held in by corrosion. Next clean out all the old grease and dirt from the drip cavity to reveal the circlip around the shaft which holds the front bearing seal.
Press the shaft from the front of the body until the circlip around the shaft almost touches the oilite bush, then the impellor will emerge from the back sufficiently to drift out the pin fixing it to the shaft and enabling its removal. Remove the spring, its brass pressure ring, the plastic shaft seal and the graphite seal and its driving pin.
If the impellor cannot be removed because of corrosion, remove the circlip. Press the shaft further from the front through the front bearing. The shaft with attached impellor, the components associated with the graphite seal and the oilite bush will be moved further towards the rear of the pump. Pressing the shaft further will push the oilite bush clear of its housing enabling the shaft to be withdrawn. The impellor can now be removed taking care not to damage the graphite seal or its associated plastic shaft seal and spring. Now remove the circlip holding the front bearing and press it out from the rear using a suitable drift.
Note that although both shafts were the same length the distance from the end of the shaft to the impellor pin hole was slightly different. Both impellors were the same but the donut ring flanges were of different thickness therefore the depth of the groove in the body for the donut was not exactly the same for each body.
Restoration.
The shaft with the least wear, about one thou.in the oilite bush area and which was also an interference fit into a new front bearing came from the body with the least wear. The associated impellor and donut ring were also in usable condition. The other shaft was very worn in both bearing areas, I will make another for the spare pump. Of the graphite seals one had cracking around the driving pin area and was worn down to the outside copper ring, the other was intact but loose in its copper ring. I repaired the cracked one with Devcon A Steel, faced it in the lathe, machined off the first two millimetres of copper and filed the driving pin slot to shape. The loose graphite seal I fixed to its copper ring with JB Weld. I also had two intact springs, one brass spring pressure washer, one plastic shaft seal intact and one without its spring. The other body was worn where the front bearing fits. Obviously it had seized, the whole bearing had been rotating. Both bodies had pitting on the graphite seal contact surface. A friend who had access to a spark erosion machine faced this surface on both bodies. In the best body, I plugged the oil hole with brass and tapped it to screw in a small flip top cup oiler. I made a back plate from one eighth thick steel sheet and purchased new screws, bearings and bushes. I made new graphite seal driving pins from phosphor bronze and stainless steel pins for the impellor. I will use a standard ball bearing and the three felt washers as shown, which I have cut from flat pieces using sharpened tube ends.
I now had enough parts to build a working pump and, with a little more effort, a spare.
Assembly.
If a remanufactured shaft is used check the shoulder length and the shaft length from the shoulder to the impellor retaining pin hole, compared with the original. These dimensions are critical as they affect the impellor to donut spacing.
Temporarily fit the impellor to the shaft and check that it spins true.
I believe that the pump originally had three felt washers to seal the front bearing. This was lubricated using gear oil pumped from the nipple on the extension piece via the hole in the pulley and the hole in the front dished washer. I think that grease can be used. The felt washers each side of the bearing may not be necessary if a sealed bearing is fitted.
First press the oilite bush into the body from the rear until about 0.5mm below the graphite seal face, then drill a one sixteenth of an inch hole through it via the oil hole.
Lightly grease the inside of the body just to the rear of the front bearing housing and smear oil inside the oilite bush. Fit the small circlip into its groove on the shaft followed by the flat washer with its projecting tag in the slot on the increased diameter of the shoulder. Felt washer number 3 is next, followed by the dished washer and felt washer number 2. Having greased the front bearing, press it a little way onto the shaft and insert the assembly into the body. Press the bearing fully into its housing and fit its retaining circlip. Do not allow the circlip on the shaft to contact the oilite bush. The shaft should now project enough beyond the rear of the body to fit the impellor and sealing components.
The correct location of the shaft in the body is determined by the fixed front bearing and the shoulder on the shaft pressing on the dished washer and the front bearing centre. The shaft is drawn through the front bearing by the castle nut against the pulley.
The problem on assembly is that the graphite seal driving pin is a sliding fit into the shaft and cannot be guaranteed to stay in position with an equal amount projecting each side of the shaft. Also the spring pressure will not allow the driving pin to remain in the slot in the graphite seal when fitting the impellor to the shaft. Without some means of locating the graphite seal and its pin whilst the impellor is being fitted it is impossible to press the shaft fully into the body. I used the following method:
Cut a ten inch length of thin stranded picture wire and arrange around the impellor end of the shaft. Insert the graphite seal driving pin and place the graphite seal on the shaft. Twist the wire ends together using a backplate screw as an anchor until the graphite seal reaches the correct position with the driving pin in the groove. See photo B. On the shaft assemble the plastic shaft seal, brass pressure washer, spring, and impellor and retaining pin shown in photo C.
photo B
photo C
The impellor pin end can now be spread. Press the shaft in from the impellor end, first looking into the drip cavity to make sure that the projection on the flat washer is still in the groove on the shoulder. The wire should unravel slowly as the shaft is pressed in. When fully home gently pull out the wire, grease the front bearing, fit felt washer number 1, its dished washer, the pulley without its key, washer and castlenut. Tighten the nut to draw the shaft fully into position. Remove the castlenut and pulley, place a one sixteenth drill, shaft first, into the hole in the dished washer. Move the dished washer around so that it coincides with the grease hole in the pulley. Fit the pulley to the shaft with its key and with the drill through the hole in the pulley. Remove the drill. There is now a passage for greasing through to the bearing. All that remains is the washer castlenut and splitpin.
Put the donut ring into position and screw on the backplate. Check that the impellor does not foul the donut by rotating the shaft. If all is well, unscrew, seal the back plate with a thin paper gasket and screw in the oiler. I used a thin film of Wellseal around the donut.
I have yet to try this pump as I have not reached the stage in the restoration of my TA when I can start the engine. There may be modern equivalents to the graphite seal and shaft seal which may improve reliability. If I can find any they will be incorporated in a spare pump and I will update this article.
Bits and Pieces.
In order to decrease the load on the front bearing and to help with cooling I will be fitting a plastic fan from an MGB, part number 01 2H 4744.
Gasket paper for backplate, 0.15mm. Cement, Wellseal.
Front bearing . 4MJ12. with Castrol High Melting Point grease.
Rear bearing. Oilite bush 26mm x 16mm OD x 12 mm ID. ( Don’t forget to soak in engine oil for 24hrs.), obtained from www.bearingboys.com .
Felt washer No.1. 32mmOD x 14mmID, 4mm thick.
Felt washer No.2. 32mmOD x 23mmID, 2mm thick.
Felt washer No.3. 37mmOD x 24mmID, 4mm thick.
Castle nut M8x1. from Roger A. Ferneaux. roger49tc@hotmail.com .
Countersunk screws M6x1, stainless steel.
Splitpin 3/32inch x 3/4inch.
Graphite seal driving pin, phosphor bronze, parallel 3.5mm x 16mm.
Impellor retaining pin, stainless steel, tapered from 3.5mm. Shorten to 21mm.
Material for shaft; Stainless steel, overall length 125mm, diameter 12mm ( 14mm at shoulder), other dimensions as for the original shaft.
I
am indebted to Bill Davis, www.billdavis.org/MGTA/
for the drawing and to members of the mg-tabc group
for their advice.
Any
correspondence to robbut@onetel.com
Bob Butson January 2010