low voltage

I have a 90 xj limited and on my volt gauge is reading like 11 volts I assume it’s about ¼ of it, I check the terminals I clean them and also the alternator, and also I have little overheating problem I search the forums but I cant find the post where they explaining how to fill the close cooling system does any one know where can I find it

I have an '88 and my voltage also reads low. Get a hand-held voltage meter or multimeter and check the voltage at the battery. My gauge is wrong. When it reads approximately 11.5 volts, the voltage at the battery and at the cigar lighter plug is always between 13.5 and 14 volts.

also i just fix the a/c and when i turn it on the belt make noise and the volts go down and as soon the noise goes the volts going up again you think is the alternator

As far as filling the closed cooling system, open the tank and add coolant, then start engine and run with cap off and heater fully on until it is warmed up. You must let engine get warm enough to open the thermostat. As it heats up, the engine will "burp" and level in tank will drop. Add coolant when this happens. This may happen several times. Run engine until it is fully warmed up, and has not burped for a few minutes, then make sure coolant level is correct and put cap back on. If the system is otherwise healthy, it should now idle without overheating. By the way, you should be sure not to overtighten the cap, because the rubber gasket will distort and let off pressure. After it has been shut down for a few hours, you can go out and loosen the cap. If you can hear the pressure escaping, it is good.

Eagle said:

I have an '88 and my voltage also reads low. Get a hand-held voltage meter or multimeter and check the voltage at the battery. My gauge is wrong. When it reads approximately 11.5 volts, the voltage at the battery and at the cigar lighter plug is always between 13.5 and 14 volts.

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Ditto with my '87. The dash gauge is wrong - it shows right at the top edge of the red zone for low voltage, but the external meter shows in the 13.5 + range with the engine running and about 12.5 to 12.7 with the engine off (IIRC). The only way to check for sure is to get a hand-held voltage meter like Eagle says (about $10 for a cheap one at Radio Shack).

let me try this, also i replace the water pump and i decide not to put the thermostat and i was serching the threads and all of them recomend to use it is there any side effects not using it

herreraxto said:

also i just fix the a/c and when i turn it on the belt make noise and the volts go down and as soon the noise goes the volts going up again you think is the alternator

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I think the belt isn't tight and is slipping. The 'noise' is hard to figure out over the 'net but that sounds about right that it makes noise, you don't have power, then when the noise stops you get power again...belt is loose.

herreraxto said:

let me try this, also i replace the water pump and i decide not to put the thermostat and i was serching the threads and all of them recomend to use it is there any side effects not using it

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¡Cuidado!

Es muy importante usar el termostato. La computadora para su Jeep no controla la combinación de combustible para los datos de los sensores hasta las ascensiones de la temperatura a encima de aproximadamente 170 grados F (aproximadamente 77 grados C). El motor se diseñó para operar en una temperatura de 195 a 210 grados F (90 a 100 grados C).

Cuándo el motor tiene frío, la computadora entrega el combustible según un mapa del combustible constanta que es una mezcla muy rica. Si usted opera el Jeep sin el termostato, siempre estará usando este mapa del combustible rica, y la economía del combustible será terrible.
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Be careful!!

It is very important to use the thermostat. The computer for your Jeep does not control the fuel mix using data from the sensors until the temperature rises to above approximately 170 degrees F (approximately 77 degrees C). The engine was designed to operate at a temperature of 195 to 210 degrees F (90 to 100 degrees C).

When the engine is cold, the computer delivers fuel according to a constant "fuel map" which is a very rich mixture. If you operate the Jeep without the thermostat, it will always be using this rich fuel map, and the fuel economy will be terrible.

My '90 XJ 4.0 got 15mpg with stock sized tires and no thermostat, but the heater worked like garbage.

I put the thermostat in about the same time I upgraded to 235 tires, and now get 14ish mpg.

i am going to try without the thermostat because the area where i live theres a lot of traffic and i stay for to long stuck on it