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Pump Up The Jam - UPDATED



The bushes were shot in my alternator, it was quite noisy and the 'L' light would glow slightly while the engine was running. To be fair, it had no charging issues and this could be high resistance somewhere in the wiring. I had tightened the fan belt as this was quite slack and I could see the alternator deflect due to the poor bushes which had turned to mush. Following this I had noticed a small dribble of coolant coming from my water pump so I assume that the extra load from the fan belt may have pushed the bearings over the edge. Pushing on the fan, I could feel some play in the shaft. Time for a new water pump and alternator.

I bought a new Graf water pump from Blunt and on an impulse bought an AL41X alternator as an upgrade since this is supposed to be a bolt in upgrade. The alternator was a Bosch Premium rebuild and came without a pulley. When compared with my original alternator I could see that the shaft was longer than the original. After stripping the pulley and trial fitting I could see that I was going to have a few issues fitting it beyond just the length. Firstly the woodruff key on the new alternator was much wider than the old and the unthreaded portion of the shaft was wider which would prevent the existing pulley, fan and spacer washers from being compressed by the nut. Certainly from what I have read the AL41X is liable to come with a longer shaft in some cases but I am conscious that I don't want to bodge it into place. I need to get the correct pulley and spacers to fit so I am going to put this on a shelf until I can find one at a scrap yard.


I really didn't want to put my old alternator back as it was in a sorry state so I elected to get mine rebuilt by a local specialist in Adelaide. If I do get around to fitting the AL41X at some point then I will keep the rebuilt one as a back-up which can't be bad.


I removed the radiator, kidney grill and the left side grill to get access to the water pump. The fan, water pump pulley came off easily after easing back the locking tabs on the bolts and unscrewing the four bolts. The 6 and 8mm bolts around the water pump came out next though a few of these had corroded slightly in position so needed a firm hand to withdraw them once loosened. The mating surface of the front cover was then treated with gasket stripper, scraped and finally brushed using a nylon abrasive brush in an electric drill which is good for cleaning things without gouging or removing too much material. After a good wipe clean, I applied a thin scrape of Permatex Ultra Black to the surface before pressing the paper gasket into place. The Permatex is not really there to provide a seal, more to stick the paper gasket into place to help assembly. The new pump was inserted and the bolts run up by hand before torquing in a criss-cross manner.


I reinstalled the hoses with a few new hose clamps and reinstalled the radiator. I had given this a reverse flush with a hose when removed but it was already pretty clean as I try and keep my cooling system in good condition as it gets pretty hot here in Adelaide.


Overall, one of those non-sexy jobs that needs to be done but it does improve your confidence in the reliability of the car.


OK, so I heard back from my alternator guy. My original alternator had somewhere along the path of life lost a diode from its rectifier pack. This explains the dull glow of the 'L' light which I have had since owning the car but never done anything about since the battery never had any issues with charging. In fact, in the 10 years I have owned the car, I have only replaced the battery once (recently) after leaving it uncharged for several years. Whatever that alternator was doing, the battery was happy enough.


Missing diode in the centre.

Looking at the rest of the stripped parts, it was in a pretty sorry state. The commutator rings had worn badly and would need turned in a lathe plus both bearings were pretty noisy. Recommendation: get a new alternator, I didn't disagree.




When I explained what had happened with the AL41X, he said he would have a look at finding a pulley to fit. After some rummaging around and the sound of an impact wrench he came back with my original pulley fitted to the new alternator. He had widened out the key way in the pulley and added an additional spacer. Price for stripping and diagnosing my old alternator, adding the pulley to the new including an additional spacer plus testing the new alternator? No charge - can't say fairer than that and I will definitely be back again.

After reterminating my wiring and bolting into place, I spun the cooling fan to its closest position to interfering with the pulley. Even here there is approximately 1/2" clearance and since the fan blade tips are supposed to bend towards the radiator at speed, I guess this is OK, revving the car hard has not revealed any issues.


All finished and buttoned up, the car started and the 'L' went out quickly leaving glorious blackness in the instrument panel. I checked the output voltage 13.65V and called it a day. I am also going to claim, as a few others have, that fixing my alternator has improved my idle. Really accept that this could be my imagination, as I am not sure I understand what the mechanism might be. This is especially so after fitting the CDI multi spark ignition since the coil output doesn't really have any connection to the battery voltage any longer (plus I had measured the voltage output on many occasions). The only other thing that could have an impact being the presence of unrectified AC 'ripple' from the alternator and this has an impact in some way. I need to sit down and work out what the impact of only half-wave rectification might be. Overall, very happy with the project.



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Man, I think this is the solution to my problem too. The "L" light comes on but car runs fine. Stereo cuts out at high RPMs but other forum topics tie it back to the alternator as well. 


Awesome write up. 

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I'm in this situation currently, I have the stock alternator on my 75 2002 and I'm looking to do this Al41x upgrade because of the 65amps it puts out. As far as the  pulley, it seems like all you need is a little man power and drilling to make it fit?

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