Jeep Grand Cherokee Oil Pressure Problems

by Jim Hagerty

Oil pressure problems are common in the Jeep Grand Cherokee, especially in older models that are starting to rack up the miles. As the vehicles ages and experiences use, excessive transmission wear and oil thinning is common in the Jeep Grand Cherokee engine. While many drivers often find this to be an aggravating problem, there are several solutions that insiders have found to be helpful.

Common Symptoms

Jeep Grand Cherokee oil pressures problems are responsible for a significant string of symptoms. When pressure is low, especially in cold weather, getting some engines to turn over and start can be difficult. Others will will start immediately, only to have oil pressure drop suddenly, causing the motor to sputter and engine and oil gauges to light up. Oil pressure will likely drop when an engine starts to leak or burn oil. Leaky valves and seals are commonly the cause. This will be evident if spotty puddles of oil are seen under the vehicle.

Using Proper Oil

Most older Jeep Grand Cherokee engines (4.0L), call for 10W-30 oil for most driving and weather conditions. This is usually an acceptable oil, however, as Cherokee engines begin to wear, oil has the tendency of thinning considerably. Some Grand Cherokee drivers have attempted to remedy this common problem by using heavier oil. Heavier oil may fix the problem initially. However, in time it usually causes the hydraulic lifters to tick and knock. It is best, therefore, to follow Jeep's recommendation and use 10W-30 coupled with a solid oil treatment application.

Connecting Rod Problems

Connecting rods on high mileage Jeep Grand Cherokee engine has the tendency of dulling and wearing out of round. This causes a separation at the parting lines. This condition is often the cause of sudden and prolonged decreases in oil pressure and is not commonly detected during normal inspections. Mechanics who routinely repair the Jeep Grand Cherokee are usually the only techs to spot such conditions. Repairing out of round connecting rods involves machining them back to shape and resetting oil clearances so that the proper amounts are able to make their way to engine parts.

Oil Treatments and Maintenance

Jeep Grand Cherokee oil pressure problems are commonly tackled with ongoing maintenance and recommended applications of oil treatments. Depending on the severity of the problem, most drivers report that using a standard oil additive (see Resources) remedies the problem. Oil treatment helps oil retain its thickness and allows it to flow as it should.

Routine filter changes and oil pressure tests usually keep the engine running as smoothly as possible. Oil pumps on the Jeep Grand Cherokee are also known to fail in high mileage situations. Bad pumps sometimes will prevent oil from flowing steadily causing consumption and disruptions in pressure.

Sending Unit Problems

The oil sending unit measures oil pressure and sends a signal to a sensor which engages the "Check Oil" or other gauge inside the Jeep. When oil loses it thickness and causes pressure disruptions the problem often results in a clogged galley, which runs to the oil sending unit. This can sometimes cause a difficulty in the sending unit reading the correct oil pressure. The unit, located near or below the distributor is usually taken apart, sprayed clean. The engine is then allowed to start with the part removed. This blows the galley clear of obstructions and dirty oil consumption.

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