more info on alt.

1948jr · Jan 28, 2018

This is a 265 massey diesel I changed temp. gauge from electric to other type and ever since I have to rev engine to make charge. Did changing temp. gauge cause this and will it hurt anything?

old · Jan 28, 2018

You probably knocked a wire loose some place so it does not excite the way it should so I would look for a loose wire that goes to the excite circuit of the alternator. By the way it would help if we knew what alternator was on it

David G · Jan 28, 2018

That should not change anything, but does reinforce the theory that you have a wiring error, maybe you disconnected the excite circuit accidentally.

Bob · Jan 28, 2018

BEFORE you mucked around in the instrument panel, did the tractor have a functioning alternator/charge warning light? IF so, does it now?

1948jr · Jan 28, 2018

No just a gauge

1948jr · Jan 28, 2018

One wire went to the temp gauge before I changed gauges

JDEM · Jan 28, 2018

Did you ever mention what type of alternator? All I saw is "three wire" which refers to many makes of alternators.

If you have a Delco 10SI or 12SI - and know for sure it has a non self-excite regulator inside - then I have some questions.

First how do you know it has to speed up to get excite current? Did you check the excite wire and find near no voltage at low RPM?

Second - when you say you have to rev it up to charge - do you mean only once when you first start it, or does it stop charging every time you drop back to idle speed?

Most alternators must spin at least 1500 RPM to do anything. If your alternator pulley is 2 1/2" diameter, and the engine idles at 800 RPM, then the crank pulley has to be 4 1/2" or larger. If the alternator pulley is 3", then the crank pulley has to be at least 5 1/2" diameter.

If the alternator is known to be spinning fast enough, and you have verified it gets field current over 8 volts, then it is likely the alternator has a problem.

If the alternator seems to be the problem, have you tried full-fielding it with a metal pin stuck in the test-port in the back (if an SI series)?

guido · Jan 28, 2018

Hello 1948jr,

The old gauge most have had ignition voltage then!
The alternator needs it to exide the circuit,

Guido.

JMOR · Jan 28, 2018

(quoted from post at 13:29:55 01/28/18) That should not change anything, but does reinforce the theory that you have a wiring error, maybe you disconnected the excite circuit accidentally.

robably as David & Bob suggest. I think those excited off the oil pressure switch. Look for disconnected wire.

old · Jan 28, 2018

Well that wire is likely to have been the excite wire then and some one used the power going to the gauge to power up the excite circuit

more info on alt.

1948jr

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