Help Needed, Oil in Spark

[Karcastic]

Hi everyone,

I have a 98 4.0 that has oil in the #3 spark plug and I usually get away with changing it out when it acts up, 2-3 times a year but I'd like to know how it's getting in there. One time I had the ceramic crack from I assume some coolant but just once a year or so ago. Not worried about coolant gasket leaks. For the past few days misfire has been worse than usual. I was gunna check audibly with a screw driver against the injector to see if it's opening/closing. Maybe it's being a pain now.

Any help/input is greatly appreciated

Truck has 330k on it, I bought it at 180k in 2010 and it's been very reliable. Only changed the alt, batt, sparks, wires, tires, brakes and fluids as scheduled/required.

Thanks everyone

Update:
I found out why I've been missing on cylinder 3 bad lately, turns out where the sparks wire plugs to the coil, it was shorting and arcing. Looked at the connections and found lots of grit and some melted rubber. Fixed with CRC ELECTRICAL CLEANER and all went well over my day of driving. Now I gotta burn out the excess oil built up from missing so much lately.

So this adds a question, could a coil/distributer start to fail like this?? Maybe giving more spark to that one compared to others?? I noticed you could get arcs to your finger a couple inches away before cleaning, an now that I cleaned the connection if I try hard enough I can still get a random one spark out of it on my finger when running but no more shorting while running. Maybe the wire jumped loose and was arcing all by itself and melted some of the rubber (inside rubber touching connector, not the outer casing)

I've been reading other similar posts on here about oil in spark and I guess it leaks from cylinder slightly from play (330k...) not from above/outside, down to outside of spark then slowly in, but I guess I should find a mirror to check properly.

 

[cp2295]

4.0s have coil packs so when it fails, it just fails, there's no moving parts to wear out. i'd replace the wires since they're shorting out like that (probably just old and not sealed anymore). To check how the oil is getting in the cylinder simply run a compression test on that cylinder.

Do a dry test (meaning you don't add anything, you simply unplug the coil pack so it can't start and then take out the #3 plug, and plug in your compression tester). Then crank the motor for about 10 seconds. After that add about a tablespoon of oil, crank the motor again for another 10 seconds and compare results. This is called a wet test. If they are the same then your valve seals need replacing, if they're different your piston rings are worn out and its time for a rebuild. While you're in there i'd run a dry/wet test on all the cylinders just to see how they are sealing.

 

[Karcastic]

4.0s have coil packs so when it fails, it just fails, there's no moving parts to wear out. i'd replace the wires since they're shorting out like that (probably just old and not sealed anymore). To check how the oil is getting in the cylinder simply run a compression test on that cylinder.

Do a dry test (meaning you don't add anything, you simply unplug the coil pack so it can't start and then take out the #3 plug, and plug in your compression tester). Then crank the motor for about 10 seconds. After that add about a tablespoon of oil, crank the motor again for another 10 seconds and compare results. This is called a wet test. If they are the same then your valve seals need replacing, if they're different your piston rings are worn out and its time for a rebuild. While you're in there i'd run a dry/wet test on all the cylinders just to see how they are sealing.

Thanks for the response, I'll be replacing all wires shortly and I'm wondering now if it's just my fuel injectors acting up because once I fixed the misfire issue(new spark and wire clean), the check engine light cleared itself as I drove, and drove great but would be ruff still as I pressed the gas but ran smooth gas to no gas. If I try to maintain speed tho, it's ruff... Is that pointing to a bad injector? If not I'll be running compression tests.

 

[RonD]

Fuel injector is fine.
You can get an OHM meter and test it, it should be about 14ohms

Change fuel filter, $10, if you haven't already, it can limit fuel flow at higher loads/speeds.

Clean MAF sensor, it is easy to do and dirty MAF sensor will cause bogging: http://www.therangerstation.com/tech_library/CleanMAF.shtml

Oil fouling of a spark plug is easy to see on the spark plug tip, as is leaking injector
Google: spark plug condition
Lots of pictures of what to look for.


Oil comes from the intake valve guide seal, in the valve cover area inside the valve spring, the vacuum in the intake manifold when engine is running causes oil to be pulled in from the valve cover area past a leaking seal.
Seals can be changed without removing the head.
(compression will always go up on a dry then wet test, that is normal, if there is a more than 25% increase then it could be ring issue)

Also next time you are at an auto parts store most will read the "history" codes from your OBD II computer for free, write down the codes and look them up or post them here.
Every time CEL comes on a code is stored, it also stores codes that do not cause CEL to come on, so lots of good info in there.

 

[bmerr98]

While you're at it check those spark plug gaps! 330K and counting...roll on, Ranger Buddy!

 

[cp2295]

(compression will always go up on a dry then wet test, that is normal, if there is a more than 25% increase then it could be ring issue.

That Makes Sense Thank You For Correcting Me!