4000 oil pressure.

[firemanpat2910]

I am helping to work on a 72 Ford 4000. Its main problem right now is the oil light stays on. We replaced the sending uint, and still have problem. The engine seems fine to me, Oil seems to be pumping. Is there a way to hook a gauge in the place of the light, Even if only Temporary? What kind of pressure should we have? The tractor got rewired sometime in its past, The battery is dead is it possible to have the charge light and oil light crossed?
Any suggestions would be appreciated.

 

[Soundguy]

I don't have a 4000.. i have a 5000.. but we can check it pretty easy.

You should have a grounding type sender.. we can check this with an ohm meter or a test lamp.

With the engine off.. you have no oil pressure, the sender will be grounded, thus your oil lamp will be 'on'. To illustrate this.. charge the battery, connect your est lamp clip to batery power, and probe the sender.. lamp should light. crank engine up.. when oil prssure comes up.. lamp should go out as the switch is opened. Keep in mind.. most of these switches open at 6psi.. etc.

Make sure you got the right sender.. or that it is wired to the correct indicator lamp.

For piece of mind.. I'd go get a 9$ cheapy manual oil gauge from the auto-store.. Sunpro makes a 9$ cheap unit.. no frills.. but it shows oil pressure. sunpro also sells a 5$ adapter kit that comes with lots of bushings.. etc.. kit comes in sae and metric... get them both and keep them for later use.. Hook up the gauge and see what ya got. I wouldn't be surprised at 40-60 psi.. though i wouldn't be worried at anything 15psi or higher at idle.. thogh more is better.. etc.

That unit still have a generator? if so.. it was a lucas. I can tell you how to check, polarize, and full field and motor test it.. also how to clean the lucas regualtor..e tc..

Soundguy

 

[firemanpat2910]

Well finaly got time to work on the 4000. Soundguy you were right on the pressure 50psi. the tractor got rewired sometime in its past. The charge light and the oil light got switched in the dash. The battery is almost 10 years old so its probably no good we left the charger on all week end and its still low. The $5.00 pressure tester from HF had the correct size adapter on it.
Thanks again soundguy for your help.