Here's a few photos I took while rebuilding my 4bd1 water pump recently.
Not a hard job, but I personally wouldn't attempt it without access to a press.

The reason for the rebuild was that the pump was leaking coolant out the front bearing. Turned out the normal seal drain hole was so blocked with gunge that the coolant couldn't get out there after leaking past the seal, and eventually made its way out past the bearings

This pump was on an engine from a Isuzu Stage1, but as far as I could work out from the parts manual should be the same as other landy Isuzu's.

Some related info here: http://www.aulro.com/afvb/isuzu-land...p-options.html

References used were the Isuzu engine manual, and the 4bd1 export parts breakdown.

Firstly, remove water pump from the engine, and remove the pump backing plate.



Made up a crude puller to remove the impeller from a bit of 10mm flat steel, some 8mm HT bolts (thread is 8x1.25 from memory), and a 12mm bolt and nut.



The impeller removed:



The main seal is in 2 parts. A fixed part that is pressed into the housing, and a second part comprising a rubber cup and hard plastic disc that fits into the impeller and rotates with it.



Press off the pulley drive flange and then remove the dust cover



Remove the circlip under the dust cover, the press out the shaft and bearing assembly from the impeller side


There is a thick malleable circlip on the shaft, and a spacer washer. There is no need to remove the circlip - just press the bearings off the other end of the shaft.
In my case the shaft was badly corroded and would be replaced, along with the circlip, spacer washer and bearings, but I still needed to disassemble to re-use the spacer tube between the bearings.



Old corroded shaft compared to the new one. I fitted the new circlip by squeezing it on with a large pair of pliers.



Remove the secondary cup seal , and the stationary part of the main seal from the housing.
Sorry no photo of this step, but the secondary seal comes out the bearing side, and the main seal comes out the impeller side.

Re-assemble the bearings, spacer washer and tube spacer onto the shaft


Fit new secondary and main seals into the pump housing

Then press in the shaft assembly and fit the retaining circlip.


Fit the dust cover and then press on the drive flange



Fit the rotating part of the main seal to the impeller, rubber cup first then the hard white plastic disc, then press the impeller back onto the shaft until you have the correct clearance between the housing and the impeller vanes.


Finally, fit the backing plate and gasket, before refitting the pump to the engine.


Happy pump rebuilding to y'all - Steve