Question about 1990 Jeep Wrangler

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I have two questions. I have a 1990 4.2 liter Jeep Wrangler. It was sitting for 2 years and would jump but not charge. I replaced the alternator. Now it will charge but only to about 8-10 on the gauge. What else should I check? Also my v-belt broke last night and the car overheated. I think the thermostat is ok because the top hose was hot. How do I tell if I need a new water pump or radiator? Is there anything else that I should check?

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First, have your battery fully charged and load tested (even if it was new). Then, put a volt meter across the battery leads while it is running. At idle it should read between 12.9 and 14v usually better than 13v. Then turn on all accessories including high beams. Volts should not drop below 12.5 and should not continue to fall with time. If it does then you still have a charging problem. (some regulators are part of the computer if alt is definitely good you may need a regulator...scrap yard part is usually a good bet)
Before you replace the belt, check that all drive pulleys are turning smoothly and none are loose side to side. Then replace the belt. Even if the thermostat was good, it is always wise to replace it after an overheat as they can then become unreliable. If your water pump is not leaking and the shaft bearing is good, don't change it. Jeep radiators are notoriously small and have no leeway for problems caused by internal obstructions. Since the fill neck is offset and the core location is difficult to get to, traditional methods of determining blockage are nearly useless.
Best way to tell if it's plugged is that it will not accept re-fill unless you literally dribble the new coolant into it or it will overflow. Radiator flush chems will tend to loosen up internal rust in the engine and can sometimes actually worsen the problem. In general it is best to replace it, however you can mix flush with a gallon of water remove the radiator and lay it flat and pour the flush into it, wait an hour or so then empty it out and flush residue out with a garden hose. This will work on marginal blockages.(careful with chems, they are caustic) You can run a garden hose through the block to clear loose rust from there while the radiator and thermostat are out.

Posted on Sep 25, 2009

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Well if u didnt yet buy a new battery. Batteries can only be charged so many times. With new alternator and battery it should be fine. Now with it sitting for 2 years im sure the radiator needs to be flushed. Change belt. Then empty the radiator fluid and run fresh water though it. I usually leave the drain plug out stick the garden hose in and let the water run with engine off till it comes out clean. But what you should do is empty it. put drain plug back in.Fill it with just plain water run it for a little while 20-25 min. let it cool. empty it again and it should clean it out. then fill it the 50/50 way. They also sell radiator cleaner. Water pump usually leaks when its bad.

Posted on Sep 25, 2009

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