Thread: Isuzu power steering pump seal replacement

This began as a "How to" but perhaps should more appropriatley be a "How not to". But first to set the scene...

Back in 2004 I was checking over my Isuzu County when I noticed the power-assisted steering reservoir was way overfull, and instead of being that nice, rich red colour auto trans fluid should be it was dirty oily black. And typically this was a week before I was due to get married with my County being pressed into service to deliver me & my best man to the church on time.

Straight away I knew the problem (I had seen it before on one of my trucks) -the oil seal in the engine driven pump which separates the motor oil from the PAS fluid had failed allowing engine oil to go through the system. The quickest solution at the time was to swap pumps from a spare engine I had. After about an hour or so labour the job was done and I got to chapel on time. So the pump sat onto the workbench until I decided just the other month to get sorted.



Place the pump in a vice using soft wood to protect the gear. The tab washer holding the nut has to be bent flat. Then remove the nut (24mm from memory), followed by a circlip & washer and then the gear should slide off.


The shaft should come out without too much drama.



The shaft after it is withdrawn from the pump showing the failed seal.


Clearly visible are wear marks on the shaft where the seal had worn. My local Jap truck spares outlet said no parts were available. A speedi sleeve was the answer.


Pushing the new seal ($8.25) into the pump housing. I used Loctite No 3 Aviation form a gasket to help retain the seal.


The seal flush inside the housing. The original seal is a NOK AE1029E. The replacement is a KOK brand.


The speedi sleeve to suit the 20 mm shaft.


The speedi sleeve has a lip & comes with a special tool to help push it on over the shaft - obviously it's a very firm fit. This is where I stuffed up. I should have removed the bearing (which was still in good condition) from the shaft to push the speedi sleeve further so the seal sits on the sleeve correctly.


The end of the speedi sleeve is designed to be removed if needed for clearance reasons. Once removed this led to my next problem...


I then had no easy way of pushing the sleeve another few mm along the shaft. Luckily I had an old needle bearing from a truck gear lever linkage
which was a perfect fit over the shaft. It didn't damage the sleeve (very miniscule marks which I used 1200 grit wet & dry to rub down)


While I had the pump apart I removed the hyd fittings and re-sealed them with Loctite 567 - magic stuff. This is liquid teflon, like a paste. Excellent for all sump, diff plugs etc etc. Better than teflon tape.


Re-fit the shaft into the housing - lube the seal with ATF or a silicon/rubber grease. Tighten the nut - 58 Nm - 72 Nm & bend the lock washer over the nut.


The finished pump with a new coat of paint.


This is the gear on the engine which drives the gear on the pump. I fitted a new O-ring onto the pump which seals it to the block (78 mm x 3mm)


The pump back on the engine. Tighten the bolts (M10 x 60 mm) to 20.3 ft-lbs to 34 ft-lbs. Jobs done!



Rob W

Just finished doing mine.
The replacement seal P/N is TC12440 (40x20x7 twin lip nitrile rubber).

SteveG