My recently acquired e-type was converted from a generator to an alternator using a kit that the previous owner purchased from XK's Unlimited. He also switched to negative ground. Everything works wonderfully except the gauge. It now seems to indicate alternator output, in reverse. The more power that I am using (lights, fan, etc.), the further the needle travels into "D" territory. The system is however maintaining itself properly; the battery is not going dead nor boiling over.

I asked XK's if this could be corrected, and was told that it could not. This baffles me. If the gauge is not correct, couldn't I get a gauge from a 4.2 and wire it in somehow so that it worked properly?

1951 XK 120 OTS RHD; 1963 E-Type FHC; 1984 XJ6 VDP

Submitted by htech@cwnet.com on Mon, 10/10/2005 - 16:40

If your engine was running above idle and the alternator was operating correctly when you were running the fan and lights then I would agree with the analysis of Michael Eck.

Under those conditions, the gauge should be reading in the vicinity of center or slightly to the right of center. Tom Hughes

Submitted by rbrand@grtnw.com on Mon, 10/10/2005 - 15:10

No, I have not tried that yet. I live a few thousand miles from where I have the car, so am trying to get my ducks in a row to fix on my next visit. Wouldn't reversing the wires on the ammeter only cause it to read in the opposite direction? My objective is to try to get the charging indicator to stay centered when thigns are correct. Right now, it reads about half way to one side of the gauge when the coling fan is on, and three-quarter way to the same side of the gauge limit when the lights and fan are on. It seems to me that the gauge should stay centered as long as everything is in balance, which I believe to be the case since the battery stays good, along with the aftermarket voltmeter that I would like to be rid of that is now in the "cubby".
1951 XK 120 OTS RHD; 1963 E-Type FHC; 1984 XJ6 VDP

Submitted by htech@cwnet.com on Mon, 10/10/2005 - 13:28

You have had two accurate possible diagnosis of your problem and cures, did you try reversing the wires on the ammeter?

I much prefer an ammeter to a voltmeter although having both would be the best for early warning of an impending problem. Tom Hughes

Submitted by rbrand@grtnw.com on Mon, 10/10/2005 - 12:43

So, is the charging indicator on the 4.2's a voltmeter as opposed to an ammeter on the 3.8's? That should be easy to hook up, what do I need to do with the wires currently plugged into the ammeter? Anyone know offhand what years will work so I can shop the junk yards?
1951 XK 120 OTS RHD; 1963 E-Type FHC; 1984 XJ6 VDP

Submitted by MikeEck@optonl… on Sat, 10/08/2005 - 18:02

Sounds like you have the alternator connected directly to the battery. If you do that, all loads will be seen as discharges and there will never be any charges to counterbalance them, because the charge is going directly from the alternator to the battery and not through the ammeter.

www.jaguarclock.com
'51 XK120 OTS
'62 3.8 MK2 MOD
'72 SIII E-Type 2+2