Chrysler Repair: Jeep problem:oil leak near filter housing, coolant temp, steady drip

Question
Hi Roland , I replaced the coolant temp. sensor like you said and it helped. I have another problem with this 4.0 inline 6 cylinder , I have noticed from when we got it around the oil filter has a steady drip of oil coming from around where the oil filter screws on or somewhere on the piece that extends from the engine that the filter goes on. Do you know what could be leaking ? Every filter I put on leaks and I can't see a crack anywhere. Thanks Dan
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Followup To

Question -
Hi I'm not sure if you can answer this because it's about a Jeep. I have 1997 Grand Cherokee 4.0 Litre engine with appx. 147,000 milkes on it. The check engine light is on and when you first start it and the engine is cold it spits and sputters and the engine idles up and down real bad , you can't even drive it till it warms up or it will shut off on you going down the road. I don't have a code reader yet but I thought maybe you could point me in the right direction as to what sensor or sensors my be bad. Thank you.

Answer -
Hi Daniel,
It probably has to do with the mixture of fuel to air being not appropriate if the engine runs o.k. after it warms up. The main difference between the mixture needs for cold vs. warm engine is the coolant temp sensor has to change its resistance as the engine warms to give the engine controller the proper signal based upon the temperture of the coolant. If that sensor is off-value when the engine is cold (behaving as if it is warm) then the mixture will be too lean. The sensor is located near the thermostat housing which is often close to the big water hose that is connected to the top of the radiator. So look aroung that big hose where it is attached to the engine to see if you can find a small sensor with a couple of wires that is screwed into the head. Remove its plug and see what the resistance is across its terminals. Then let the engine warm up and measure it again. The original resistance should be about 7,000 to 13,000 ohms (cold) and after the engine  warms up it should be 700 to 1,000 ohms. These are the values for the Chrysler engines. If that seems o.k., then it may be that your egr valve is sticking ajar and then freeing up again as the engine warms. That valve is bolted into a pipe that runs between and exhaust manifold (probably on the right side of the engine) and the intake manifold. If you examine the valve you will see it has a round device with a vacuum hose(s) attached to it and between that and the valve housing in the pipe is an open cage with a metal rod inside of it that has a slot around its circumference. That is the stem of the valve, and you can move the rod back and forth with the tip of a screwdriver. So try moving that back and forth (spring pressure will try to close the valve). See if it is closing all the way and if it seems to hang up then spray some solvent on the stem of the valve where enters the valve body and manipulate the stem some more. Then see if it starts better.
It is fairly easy to get a code readout and at some parts stores (I have heard that Autozone does it) you can have it done at no cost. Find out the code and what it means and if you have questions let me know. That readout will probably tell you why it isn't idling or running well when cold, or at least give you some clues.
Roland

Answer
Hi Daniel,
I'm glad that the coolant temp sensor change improved your cold start problems.
On the oil leak near the filter adapter, usually the oil pressure sensor-sender unit is also located nearby, and those often will begin to leak because of the design requiring them to measure pressure and also handle electrical currents so there is an interface between the metal housing and the insulated electrical connection. So see if there might not be a single wire small sensor screwed into the block very near the filter and examine it for being the source of the leak. It is inexpensive and easy to change but be careful because the threads are often tapered to provide an oil tight seal, but that also means that if you overtighten the sensor in the hole you can crack the metal surrounding the hole. So just snug it up but don't put excessive torque on it.
That is the most common reason for leaks, other than the filter itself. I am not familiar with the filter adapter but generally these are not removable so they should not leak.
Roland