A few items of concern

1) Fuel mileage is reduced.
2) Front wind shield leak.
3) Valve cover leak.
4) Ball joints on their way out.

1) Fuel mileage should be an easy fix. The present O2 sensor is Auto Zone bought 7 years and about 50,000 miles ago. This board recommends the NTK (NGK) unit. The local Jacksonville FL NAPA have them for $53 plus tax. Summit have several for the 4.0L (I do not remember the price), but which is the correct one for the XJ? I have to weigh the cost of each and make a purchase. What part number should I buy if I buy online?

2) Windshield leak. My 1994 XJ was an easy fix when I had the '94 XJ. The 1996 is a whole different pot of tea. Could it be repaired by a novice in the drive way or should I take it to the pros.

3) Valve cover leak. Easy fix for me. In my previous career, I was a heavy equipment mechanic then a power boat mechanic.

4) Ball Joints. It is drivable and I think safe. No funny steering problems. However, I need to re-build the entire front end starting with the gears ie; changing the 3.55 gears to match the 4.10 in the rear since 2008. Replace all the steering linkages. Replace the hubs (Bad bearings. I am presently using a set from a 2 wheel drive.) The front drive shaft was removed when the rear axle was re-geared in 2008. The axles were removed 5 months ago when I installed the hubs I am using now. And last of all the ball joints. Every thing on my XJ are still original and going on 275,000 miles.

The XJ now rolls on a pair of worn 32" tires that actually measures 31". I put them on there to see if I would like the performance with that size of tire verses the 30" BFG AT's that is there since 2006. With a bad O2 sensor which was evident before I change tires make the test results inconclusive. No, I do not want to go bigger than 31 tires. The added weight of the tires do have a negative effect on gas mileage plus the extra wear and tear on every thing else do not appeal to me.

Sounds like you know what needs to be done, so get to it!
How the rust doing ' in the islands'. Island cars often rusting out before they wear out.

Do you need an up or downstream O2 sensor?
Rock Auto has NTKs, up and down, at $34 each.

"The axles were removed 5 months ago when I installed the hubs I am using now."
You are not running front axles? What 's holding the hubs together?

He said he installed 2wd hubs.

How bad is the windshield leak / can you tell why it is leaking? I.e. is there rust or body damage around the windshield? If not, the adhesive is probably no longer sealing it to the body at some area, not uncommon I'm told. My previous '87 had a windshield leak, PO tried to fix it with silicone around the outside, didn't work. I had the windshield replaced since it was cracked anyway and that took care of the leak.

31" tires should be a nice match for 4.10 gears... I'd replace your O2 sensor and see if the performance improves.

Red91Laredo said:

He said he installed 2wd hubs.
.

Click to expand...

Whoops, missed that.

The reason why I asked about how the rust was that the windshield area seems to be a magnet for rust. The leak may not be in the windshield seal, rather it could be rusted out spots in the windshield frame.

lazyxj said:

How the rust doing ' in the islands'. Island cars often rusting out before they wear out.

Do you need an up or downstream O2 sensor?
Rock Auto has NTKs, up and down, at $34 each.

Click to expand...

I am back in the US since 2011 and living in Jacksonville, FL. I did not take the XJ to the island. Before coming to the US, I lived in the BVI (British Virgin Islands) for 15 years. The average vehicle body lasted about 5 years +/- before major body panel replacement was necessary and maybe only 40 to 50 thousand miles. About 50% of the major roadway was about 15ft from the rocks and 2ft above average water height. It was common to get your vehicle bathed in sea water along the main road.

The upstream sensor is the one I need. In 2006, the XJ did exactly the same thing,...mileage dropped by 30+% with no error or check engine light. The OS sensor got it back to what should be normal. I will look into getting one from Rock Auto.

Red91Laredo said:

He said he installed 2wd hubs.

How bad is the windshield leak / can you tell why it is leaking? I.e. is there rust or body damage around the windshield? If not, the adhesive is probably no longer sealing it to the body at some area, not uncommon I'm told. My previous '87 had a windshield leak, PO tried to fix it with silicone around the outside, didn't work. I had the windshield replaced since it was cracked anyway and that took care of the leak.

31" tires should be a nice match for 4.10 gears... I'd replace your O2 sensor and see if the performance improves.

Click to expand...

I may take it to the pros and let them go at it. The rubber around it is very hard and do not re-conform to its original shape quickly if I pull the edge up. I am afraid it may need to be replaced. If I try it myself, I may end up loosing the wind shield as well. I know the water come down from the passenger windshield area and pool under the carpet on that side. I had it all torn apart waiting for the next hard rain then went outside to look.

31" tires measure about 30.5" verses the measured 31" worn tires I have on there now. I think the 31's may be the best over all tire for the gear ratio I have now. True or new 32" may be too big for city stop and go driving. Highway performance and mileage should also be acceptable.