Hi all, picked up a 2001 Durango 5.9 a few months back, knocked out things new like tires, radiator and engine block full coolant flush, had to change the water pump a month after the flush, new transmission filter and fluid. Car had about 100k miles on it when I got it. I suspect the previous owner did not keep up on maintenance as he stated . Only thing I saw so far was that plugs did get changed once since they were NGK plugs (don't think those are OEM?). Anyways I initially ran Mobil 1 5W-30 (truck is specked for 10W-30) at around 3,500k I changed the oil over to Mobil 1 10W-30. I checked how much fluid came out and I was about 2 quarts short. I know you lose some in the filter but still suspect I burnt some oil. I have read that your first 2 synthetic oil runs will burn more oil then normal. So next issue I had pop up was a misfire. I change the plugs over to autolite iradiums, new 8mm spark plugs, new rotor, new pvc and new distributor. The distributor had 1 corroded contact point which was probably causing the misfire. Truck is running well after the tune up. I also had to tighten down the valve covers as the covers were leaking near the rear. The 7 & 8 plugs were a bit tough to get out. I think the oil from the valve covers made its way onto them and maybe even into the grooves, they were loaded with gunky oil deposits. Not sure its possible for them to go all the way into the chamber

Reading up in the forums many folks mention the plenum oil leak. I looked down the plenum this week and here is what I saw. I do see what looks like some nice fresh oil down there, well you guys be the judge. To me it looks like new oil down there but maybe this is what the leak looks like. PVC was just changed, it was still shaking normal but was probably OEM.



Here are some photos of my old plugs, they all look alike except for the 1 & 3 plugs.



Boroscope shots of inside cylinders 1 3 5 7:



2 4 6 8:



The 8 cylinder to me looks like it has some oily residue, that could be the light within the boroscope I am not sure. But as I mentioned earlier, I am wondering if oil from the valve covers could made it way into the spark plug grooves and into the chamber?

Regardless, I have a ton of carbon on the heads, need to attack that problem next. I'll be monitoring my oil closely as well. I haven't done a compression test yet but now I am thinking I should.

 

something to remember about changing over to synthetic oil later in a vehicles life, synthetic oil has better detergents than conventional oil, this means it cleans dirt/carbon ect better than conventional oil which leaves some deposits behind. If your seals are worn and seeping the conventional oil will likely leave enough residue to slow down/stop this seeping, the synthetic will clean it out when you put it in, the first change or so will do this and from there the engine will remain relatively clean. However this is why people freak out about switching later in life. As long as you are aware of it and keep an eye on the oil its not a big deal, but it is something to keep in mind. (this also applies to ring and bearing tolerances ect, basically every oil passage in the engine)

as for the plenum, i would expect a pool of oil, but iv never had a vehicle with a bad one, stick your borescope down there for better pictures.

 

If you let your oil drop two quarts low, you're contributing to the oil burn problem. Check your oil weekly and keep it topped off.

 

Think you need to fix the plenum..... notorious for the gasket blowing out.

 

Interesting thoughts on the swapping over the synthetic. I will be keeping a close eye on the oil. I am hoping after the tune up that my mileage also goes up. Only been a 100 miles or so and I am still around 12mpg (Driving mostly highway). Didn't pull the and drain the battery after.

I'll try and get the boroscope down the plenum. Have to figure someway to keep the throttle plate from closing up on me. Any thoughts on what I can use so that I don't damage the plates in the open position?

 

This! If it aint leaking now it will be later.
http://www.hughesengines.com/Index/p...p?partid=27091

 

maybe a plastic body of a marker or something similar, shouldnt hurt the butterflys to rest on the plastic.

better yet would be to work the throttle cable and use something on the arm where it attaches to hold it open