Tire Rotation and other things

Yesterday, I decided to try and stretch the life of the nearly worn out tires on the front of the 93 525i. I went ahead and rotated front to back. I looked at the tires when I had them off the car and they didn't really look that bad, so I figured I could wait until my measley tax return comes. The front tires (that were on the rear) look in really good shape. Can't decide now if I'm going to just replace all four, or put two new on.

I also, finally was able to drain the fluid in the rear end and replace it with some synthetic. I was afraid of what it might look like considering when I did the trans fluid, it was really bad. But it didn't look that dirty, although it's hard to tell with the heavy oils. The reason it took me so long to get to this was I had been trying to fabricate my own tool to remove the plugs on the differential. It takes a 14mm allen wrench. It's pretty cramped trying to get to the fill plug, so you need a short one. I tried making one out of some metric nuts and bolts, and it would have worked if I could have tack welded it, but since I'm no welder or have a welding machine it wasn't going to happen.

I went to Autozone and bought a set of three 1/2" drive allen wrenches, 12, 14 and 17 mm, for $12. I had checked on line and the cheapest I found the BMW special tool for this job was I'm thinking $35 bucks. It was just a stubby 14mm allen wrench. The ones I bought at Autozone had the allen wrench part on it about 1 1/2" long. I figured I could cut about and inch or so off and use a 14mm 3/8" drive socket. I did it and it worked perfectly. So now the rear end has brand new clean fluid in it.

The battery on the car was dying, so while I was at Autozone, I picked one up. Beforehand, I looked all over the place, the batteries for these cars aren't really easy to find. I paid $90 for this one and it fit perfect. The part number for the battery at Autozone is 49-DL.

While I had the car up on jacks, I decided to do an oil change. I had purchased some motor flush from autohausaz back when I was ordering all of the parts for the Head Gasket job on the 95. I added it to the crankcase with the motor at operating temperature, running and following directions on the can. I let it idle for 10 minutes and then shut it off. When I got the car running back in August, when I changed the oil, I added about a pint of Marvel Mystery oil to the rest of the oil. It does a pretty good job of cleaning up sludge and other gunk in a car that might not have had the best of care in the past. I found a ton of crap under the valve cover when I was changing the valve cover gasket. It had taken me a good hour or better of scraping and cleaning with degreaser and high pressure washing to get most of the gunk out of there. I figured I'd put a couple of thousand miles on the motor after I put it back together with the "Mystery Oil" in it. I was just about there when I changed the oil yesterday. I figured the Motor Flush would help get the rest of the junk out. When I refilled, I used Castrol 20W50 with the sludge inhibitors. We'll see how it works.

The car seems to run really well now. But I noticed a weird thumping like noise. It actually started up right after I had the front end alignment done. My son came home one day saying he was hearing the noise. I took it out and didn't hear anything different than the normal car noises. After I finished all of the work on the car yesterday, I drove it back to Autozone to get my core charge back on the battery I bought and noticed the noise. There really isn't a pattern to it, what it sounds like to me is something hanging up in the undercarriage and occasionally bumping the floor of the car. It only seems to do it while driving on less than smooth surfaces. I drove on a newly paved street and it didn't make a noise. I'm thinking maybe the worn tires are making some weird noise or maybe some suspension part is popping, sort of like something getting bound up and then releasing. As soon as I figure it out I'll post what it was, maybe it will just go away.