Forgot to mention that the flexplate was fine. The rattle at idle that made me think the flexplate was bad? Well, the exhaust downpipe literally sits at the bottom of the bellhousing, so that's probably what I intially heard inside the Jeep at idle in drive. That "clacking" sound I mentioned is still there, but it's quieter after giving the engine and fuel system the Seafoam treatment (this isn't a ticking sound that is typical to Jeep inline-sixes). It runs fine, isn't down on power, and idles smooth so I'm not going to worry about it for quite some time.

Bumper cover had been previously replaced (not repaired, if it had been repaired, the factory paint underneath would have prevented the peel), and was not sanded properly. Poor adhesion = peelback.

Stick with a thicker synthetic oil.

I've always been told that once you switch to synthetic, you never go back.

That's a myth.

You can switch to synthetic at any time, at any mileage. It will not cause leaks. You can switch back and forth if you like, but I just run the better product all the time.

As for Rotella, I have heard good things about it, however I personally use Mobil 1 High Mileage religiously on the Intrepid and most of the time in the Prizm. I've seen what an engine that has been running M1 all its life looks like inside, I was impressed.

Don't cheap out on the filter. No matter how good the oil, if you buy the $h!can special its not going to keep the oil clean.

Thank you, Dodgefan. That was very informative.

I would think you would want the high-mileage specific oil..that's what I use.

I prefer Wix filters. I don't waste money on anything branded "Fram."

Since cooler temperatures are just ahead, I may go to 5W30. Dunno yet.

Purolator Pro 1

I can't remember if Wix filters are basically the same as Purolator or Motorcraft.

I can't remember if Wix filters are basically the same as Napa Gold Purolator or Motorcraft.

Refreshed my memory, corrected my post.

Edited August 18, 201311 yr by black-knight

Purolator Pro 1

Purolator Pure One filters are very good filters and the ones I typically use.

A little reading for anyone interested:

http://www.cheersandgears.com/topic/39623-info-on-oil-filters/

Yea those. Memory failed me.

I decided to stick with good old Mobil 1 High Mileage Synthetic.

That engine noise, though, still haunts me. It was initially quieter after running Seafoam through it, but it's as loud now as it used to be. There is a catch, though. If you drive the Jeep for about an hour, it gets quieter or almost goes away (but not totally). Listening to the engine idle, the noise certainly coincides with the exhaust note at idle. Is it a lifter? A bad wrist pin? Piston slap? I'm stumped. I have two videos I'll put up in a bit.

The first video is of a rattle inside of the Jeep whenever it's sitting at idle in drive (in the video, I shift the Jeep into neutral to demonstrate that it quits if you shift it out of drive when the motor is at idle).

The second video has the afformentioned engine noise, although it is somewhat faint.

I think that, somehow, the two noises are linked.

Are the videos working?

Yes.

can you pick up one of those automotive stethascopes from Harbor Freight? that might help to isolate the noise.

I would get an automotive stethoscope and craw under it and start probing to see if it is coming from the engine or tranny. It might be worth it to take it to a good tranny shop and have them review the tranny to see if the issue is there. I know the place by me does excellent assessments and have been honest with telling me when it is nothing in the tranny but an actual engine issue. This could help you deduce the point of noise faster if you can remove a major component from the problem.

To me I am thinking tranny based on your videos. Something is slowly dying and the noise seems to come when you put the power of the engine against the tranny. One thought, crawl underneath and have someone move from drive to neutral and listen to the tranny and check the drive line and see if the noise shows up better.

I hate to reveal what I'm planning before the actual wheels are set in motion, but here's what I'm going to do. I'm going to have a local CDJR service department diagnose exactly what's going on with the XJ's powertrain Friday afternoon (depending on the cost). If the transmission and engine need some major TLC, I have a 4.6L stroker block (it's a gamble, but I'm going to reuse and recondition my existing cylinder head if it isn't cracked) and a new transmission on the line to go back in the Jeep. I'm going to also attempt to buy a complete 3" lift kit with new springs, upgraded front brakes, and new wheels and tires very soon too. That will sort out the Jeep mechanically, then I can focus on the Jeep's cosmetic issues and call it a day.

I'm hoping to complete this build within a 10 to 12 month timeframe, at the most. After I know the Jeep is completely trustworthy, I'm going to really shake things up a bit.

Edited September 4, 201311 yr by black-knight