Now imagine the amount of drag put on the shaft and gear to create enough heat to discolor the metal like that. As far as it turning smoothly, put it in the oven for about 30 minutes at 200F and once its nice and heat soaked and the metals have expanded take it out (with a big thick glove) and try spinning the shaft. It will have a decent amount of drag on it.
When I did this I was surprised at the level of drag it had once it was hot and had no lubrication.
Great test FOG!
I just finished reading this whole thread. Whew, it was like reading a novel. It took me two days of reading and taking notes all along as well as a little research on my own.
I want to thank everyone who has contributed in this thread for everything from their comments to continual testing, research and development.
I am going to be pulling out my OPDA soon to inspect. My Jeep has a Feb. 05 build date as well as motor build date of Feb 05. The 7th digit in the VIN (from right) is a P and she has 49K on the clock. I am the second owner and have been running Castrol GTX 10-40. I currently have no symptoms but after reading thread, many concerns.
Upon removal and inspection I will take some photos and start documenting my progress. Of course depending on what I find. I most likely will be replacing the helical drive gear, polishing shaft if necessary and doing the zerk retrofit mod as Fog has mentioned all along, including making sure there is a passage for the grease to take to migrate to the rotating shaft within the upper bushing itself.
Again all depending on what I find, I may also be changing to the Valvoline VR-1 10-30 and possibly a ZDDP additive as well.
I have a few things I would like to mention that I didn't see addressed in the thread. First, for the not so experienced or mechanically inclined. Please use caution when working with aluminum, for the most part
is an extremely soft material, when threading it with a tap for zerk ftg. installation, be careful not to strip out the threads or cross thread the hole. It is almost like butter compared to other materials. (just looking out for the less experienced).
In regards to the original hole in the OPDA where the mfr. was to have filled with grease for lubrication of the top bushing. If you remove the cap/cover from the hole and inspect as well as clean out old grease before the reinstallation of your modified unit, then you can thread the hole and insert plug(grub screw) as FOG recommended. I see it to be beneficial to do this, it allows us to have a clean out for the older grease as you pump the new grease into the unit. We actually have motor bearings at work on some of our older equipment that has this feature and it actually allows for the old grease to flow out of the hole while adding in new grease. I know that most folks will probably just add a pump of grease every thousand miles or so, but I am sure there are guys that are going to be removing their OPDA every once in a while for inspection and at that time they can remove the plug and purge out any old grease from the bushing. It is just a thought. I am sure the access for the grub screw will be in too tight of an area to do this while the OPDA is installed.
Also, once zerk is greased, the (should be) ongoing lubrication is accomplished by the heat generated causing the existing grease in the cavity to heat up and wick its way to the rotating shaft inside the upper bushing. I know it was mentioned before, but I just wanted to touch on it again. I wasn't sure everyone caught that because after reading some of the comments in prior pages it seemed like there may be folks that think the grease in the cavity is constantly under pressure and feeding to the rotating element(shaft). Only time there is pressure present, is when the grease is first applied to the zerk ftg. on the modified OPDA.
Just a thought, but it may be possible to install a tubing ftg. instead of a plug and a piece of tubing could be routed out to access where its more convenient, along with a cap to seal the tube. This may allow it to be used as a clean out while lubing the bushing zerk ftg. while engine is running. (Still thinking about this).
Anyhow, I just wanted again to thank all participants and throw in my
Whatever I decide to do, I will document and submit when completed.