L-series alternator renewal

I’ve been suffering a plague of electrical problems for the last few weeks along with the battery regularly needing to be charged. Eventually I tested the alternator output to find there was none. At least only enough to extinguish the dashboard light. I know most l-series owners will not have had to renew or remove the alternator but when you do it is not a 5 minute job!

Having realised I needed a replacement unit I set to and removed the old unit and fitted the new. There was a delay waiting for a new Continental 6PK1460 drive belt after all I could find was a cheaper poor quality item.

I refitted everything and I was delighted to see 14.5volts output but also oil leaking from the oil feed connection to the vacuum pump. This surprised me because I was particularly careful with making this connection. Nothing I could do would stem the flow.

Nothing for it but to remove everything again including the oil feed pipe which required among other things draining the cooling system. At least I didn’t have to drain the power steering this time because I had carefully fitted the long fixing bolt from the other side.

I can now see that the replacement alternator has a damaged female thread on the oil feed port. I can probably recover this with a tap and make a new feed pipe if I know what is the thread of the male pipe nut. I saw a suggestion from Nodge in an old post that it is 1/4 BSP. This one isn’t. Diameter of male nut is approx 9.7mm.
Part no. of pipe is YKL000020. It looks much like a brake pipe with metric nuts.

Any help with confirming the thread gauge will be much appreciated.

Just to round off this saga. It turns out the od of oil feed pipe to the vacuum pump is 1/4” or 6.3mm. The thread on the fittings is metric fine or 10mm x 1.25. I had both tap and die and was able to repair the damaged threads. I obtained a length of 1/4” Kunifer re-used the old pipe nuts, formed a single flare each end and reconnected pipe from oil gallery to alternator vacuum pump.
After starting engine I’m pleased to say no leaks and I saved myself £70 for the new pipe!
All in all a very awkward little job.

Blimey, that's a lot of work to change the alternator!

Think I'd have been using some colourful language and throwing spanners round the garage

If I were the type to fling spanners about at every Land Rover glitch my tool kit would have long ago been emptied! I must get a T-shirt with the slogan “Land Rover, making mechanics of their customers for more than 70 years”

However another chapter in this sorry saga! I now find that there is still an oil leak from the alternator although this time not from the oil feed pipe connection. After a long drive with the engine and oil thoroughly warmed, there appears to be a slow leak from the alternator windings! I’m assuming that this is actually from the vacuum pump rear oil deal. I’ve never seen any listings for a reconditioned L-series vacuum pump and I’m not sure how you would remove it. Presumably I will need a puller to remove the pulley? Provided I can remove the pulIey I could always substitute the pump from my old unit although I’m sure it would only be a temporary fix.

Any advice on how to fix this would be appreciated.

A further development just completed, has been fitting poly bushes to the lower engine steady bar. It’s certainly reduced the amount of engine movement between throttle on and off, which recently broke the exhaust downpipe. However the downside is that I can now feel every little engine vibration and that’s without fitting the top steady bar poly bush which I guess will make vibrations even worse!
Roll on the warmer weather!

The L series vac pump is just bolted to the front of alternator, the output shaft being keyed to the alternator rotor.
So you should be able to fit your old pump, to the replacement alternator. Often a replacement alternator doesn't come with the vac pump, so is swapped over as part of the replacement.

Thanks Nodge for taking the trouble to respond. Much appreciated! Is the pulley on a taper or will it just pull off a parallel shaft? I think I’ll wait for warmer weather until I tackle this. I just hope the oil doesn’t get transferred along the shaft to the business end of the alternator!

Happyhippo said:

Is the pulley on a taper or will it just pull off a parallel shaft?

Click to expand...

Yes, but the pulley is fitted to the vac pump, so will come away with the pump, when you unbolt the pump from the alternator.

Thanks Nodge I’ll attack the job with renewed enthusiasm now that I know I can just unbolt the vac pump. I thought it likely that they had a common shaft. I just need to order a new Continental drive belt!

Hello again!
This saga is not yet finished! I’m still getting oil drips on my paving. Although I changed the vacuum pump from my reconditioned alternator for that which was fitted to my old alternator which didn’t leak but apparently does now. It isn’t a big problem which is why I’ve not pursued it but it is very annoying.

It occurred to me that the oil feed pipe to the alternator vacuum pump might not be a plain old 1/4” pipe as I have fitted but might have a restriction somewhere to limit the amount of oil bled off from the oil gallery. If the oil pressure is unrestricted it might be overcoming the seal in the vacuum pump and also bleeding off oil and reducing oil pressure to the engine.

The oil drain or return pipe from the vacuum pump to the sump is at least 1/4” i/d and should easily be able to cope with the feed.

Also why would the vacuum pump need such a copious supply of oil?

I’ve more or less convinced myself that I somehow need to restrict the oil supply. I suppose I could always order a new oil feed pipe!!

Any observations or advice gratefully received.