Question about 2002 Jeep Grand Cherokee

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2002 Jeep Grand Cherokee 4.0L Oil gauge reading very high

My oil gauge has started to run up close to the "H" Mark It has never ran that high before.It does drop back to normal at idle.I have checked th oil,all is good.No leaks anywhere.Any Ideas.

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  • Rick Jan 23, 2009


    I do change my oil at the correct time with a quality oil.So I am hopeful the oil pump is not the problem.This just started to do this in the last week.Can I clean the sending unit?And Where is this located on the 4.0 ? Also when I turn the key on the needle goes to the middle ?Should it do that if the motor is not running.If there is no pressure in the line should it stay down until I start the engine?

    Thanks again.



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If the weather in your area is colder than normal, your startup oil pressure will reflect this, essentially because it is much thicker when very cold. This high reading should drop to "normal" once it reaches operating temperature. This condition can also be caused by a sticking pressure relief in the oil pump, usually caused by sludge inside the engine. If you regularly maintain your vehicle and use good quality oil, this should not happen. The oil pressure sending unit is also suspect, but in your case, I would not put it at the front of the list. If oil is close to "change time" consider using a good synthetic oil (synthetics flow better at extreme temps) or using a 5W anything oil during winter months. (see manufacturers specs)

Posted on Jan 23, 2009

  • Richard Scordino Jan 24, 2009

    I would not be too concerned with where the pressure gauge reads with the engine off. I define a quality oil not only by name but by parafin content that causes high temp burn off creating sludge. Once knew someone who bought a truck from guy across the street. We saw him change his oil at least once a month. I removed enough sludge from inside only one valve cover to make a semi-solid glob the size lof a softball! Your sending unit should be near the oil filter. It usually looks like a sort of bell shaped gizmo with one wire connected to the top. If you want to clean unit, it's not really a good idea. you can damage the inside of the sender and if you clean the passage it will usually drive any gunk down, where it will only come back up as loose material that will be worse than what you started with. If you want, put some marvel oil in the crankcase ... it is a very good lubricant and also gently removes gunk without being so harsh that too much gets to circulate all at once. One other thought: if you changed your oil filter and used a different brand than you always have, some have check valves inside that can screw around with pressure if valve is defective.



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