Zxr 400H/L water pump rebuild

[Kevh1070]

Zxr 400 water pump rebuild

Disassembly.

Drain coolant & oil as per normal, remove front sprocket cover plate & associated pump hoses. Remove pump fitting bolts from casings (2x M6 on vertical axis) withdraw pump from casings.
Remove pump cover plate to expose impeller, removal of impeller can be done via various methods.
1, Take a M6 x 30mm nut & bolt, use bolt to centre nut on top off impeller crown & spot weld nut to crown. Once secure use the M6 bolt to pull impeller & top section of mechanical/ceramic seal off of centre shaft.
Please note - do not overdo nut weld to impeller as material is not hardened or very thick, to do so may give rise to impeller damage beyond repair !
2, Heat impeller crown with a small/precision gas torch, taking care not to overheat pump casing body otherwise there is risk of distortion etc. take suitable leverage item & gently prise the impeller from shaft trying not to cause dame to pump body or impeller.
3, utilise a mechanical puller device if you have one that will fit into clearance areas between impeller & pump body.
Once impeller is removed prise out the top section of aforementioned seal & remove rtv sealant from internal side of impeller thoroughly using fine steel wool.
Finally check impeller is straight & true, if you don’t have a true surface such as levelled steel table your average bathroom mirror/glass pane is fine for this purpose.
Straighten any defects to impeller & remove surface deposits/corrosion deposits as required.
Removal of lower section of mechanical/ceramic seal, firstly remove the lower ceramic section & washer plate. Then prise out spring encased in a C section rubber seal, once these parts are removed you can then either cutout the mechanical seal using tin snips & pliers or drift the seal lip away from pump body & leaver it free.
Clean any damage to pump body surface area as best as possible ready for new item refit.
Shaft & bearing piece are one piece construction, comprising of 2x ball races enclosed into a 24mm(w)x33.5mm(l) steel outer case formed over bearing races by a press. To remove shaft/bearing from pump body I immersed the entire unit in boiling water for approx 10 minutes then placed pump body in a vice with jaws padded by a few layers of rags then knocked shaft through from impeller side using a large hammer or a press if you have one.
Bearing removal from shaft, a dremmel tool with a cutoff disc disc is the easiest option. Protect shaft ends incase of runoff with cutting tool, place shaft in vice & cut along bearing case length ways on opposing sides. Case will then separate from shaft, leaving shaft with pre cut bearing grooves clean & address any corrosion/damage to shaft.
Note - shaft is hardened material along its entire length.

Reassembly.

Pump body/top cover inspection, corrosion to sealing faces to pump body is not uncommon this can be refaced by using the mirror/glass pane & sheet of 320 grit sandpaper in a figure of 8 motion. Any other cleaning of pump body etc can be done with fine steel wool.

Parts materials required :-
4x NTN 6901 lob/5k bearings or similar sealed for life items.
1x 12x24x6mm(I/d)x(o/d)x(w) open race bearing
1x SKF Viton double lipped seal 12x25x7mm HMSA 10V or similar
2x external circlip unstrung diameter 11mm/sprung diameter 12mm
1x Mechanical/ceramic seal 898K:G810(Happybikes.co.uk)

First step is to check shaft measurements, mine measured 99.2mm(l)x12mm(d) including oil pump tang notch. Tang notch dimensions measured 12.5mm(l)x11.5mm(d), notch internal dimensions measured 8.5mm depth x 4.5mm width. Both shaft ends where chamfered by 1mm.
Circlip positioning using dremmel tool & vernier calliper gauges, impeller end of shaft measure 35mm toward shaft centre. cut a 0.5mm(depth)x1mm(width) groove into shaft.
From oil pump drive end of shaft measure 31mm toward shaft centre, this cut needs to be made on centre of shaft side of measurement ie circlip groove should have centre edge measurement at 32mm(l) from oil pump end.
Take the open race bearing & cut off outer shell & remove bearings, discard these parts & keep the inner collar of bearing this is used as a internal shaft spacer for remaining bearings.
For bearing/collar fitting I used various sizes of 3/8” long reach & standard 1/2” drive sockets for bearing/shaft support & fitment
Bearing fitting to shaft. Place shaft in freezer for approx 8-12hrs. Take 2x NTN bearings & drift/press them into a flush fitting position to machined section of impeller end of pump body. Remove shaft from freezer & fit open race bearing inner collar to shaft at centre position of circlip slots, insert shaft from oil pump end & drift shaft through bearings till circlip slot(impeller end) is visible.
Fit circlip & invert pump body, take remaining 2x NTN bearings & drift into place one at a time till rear circlip slot is visible & all bearings are in correct position ie impeller side is flush with machined section & oil pump end should be 1mm recessed into machined section. Once positions are confirmed correct fit 2nd circlip.
This is for clearance tolerances on both seals.
Check shaft/bearings for free rotation & no notchy sounds etc, expect some resistance due to close tolerances.
SKF viton seal fitting to oil pump end of body, place a small amount of rubber grease or similar on flat side of seal inner lip & outer edge of seal. Place flat side of seal facing toward pump body & press home by hand initially, drift into place with suitable socket until flush with pump body end.
Mechanical/ceramic seal fitting impeller end, take lower section of seal consisting of metal seal surround with spring rubber base & lower ceramic seal section. Find suitable socket to fit outer rim of seal section & clear shaft, cautiously drift seal into impeller end of pump body until flush fitting to body is obtained.
Any damage to ceramic section will render the seal useless !
Upper section mechanical/ceramic seal fitting, take a tube of suitable rtv silicone sealer & smear a moderate amount into recessed section of impeller body. Place the upper section rubber seal side to impeller recess taking caution not to damage ceramic portion & press home evenly.
Take the impeller & seat it onto the shaft end, find a suitable socket that fits over the impeller crown & seats on impeller base. Gently drift impeller into place checking visually of impeller crown position to shaft end & mating halves of ceramic seal portion, once you are satisfied they are in position refit the top cover plate with O ring seal & torque to spec(9.8N.M./7.0Ft Lb’s)
Allow rtv silicone sealer to cure for 24hrs, place pump in sealed bag or similar whilst curing to avoid any foreign objects being ingested.

Static test of pump can be carried out by by filling pump with coolant over a bucket there should be Zero leakage from drain hole under these conditions. The only real test is by refitting to motor & running up bike to thermal switch cut in & varied rpm basis prior to full road test.

Do Not Dry Run pump under Any Circumstances !
This Will Render The Ceramic Seal Useless.