I did this recently on my '98 3.1L V6. You definitely want to replace the thermostat, since it is a real bear to get to without removing some of the parts that will be removed during the LIM replacement. Also,there is an O-ring seal that goes to the oil pump shaft that sits near the valley on the driver side of the engine. This is real easy to get to with the LIM removed. The gasket kit that I purchased included this gasket, so I used it.
Also, I would check all of the hoses and the serpentine belt. You're going to be removing/disconnecting these anyway, and it might make sense to replace them while you are there. When I pulled the fuel injectors/fuel rail out of its seat, several of the O-rings were in pretty bad shape. I had purchased replacement O-rings before I started this job, and I was glad I did. Otherwise, I would have had several down days waiting for these pieces to be delivered.
You should probably also have the gaskets for the EGR valve and the throttle body. Also, there is an O-ring that might get lost if you disconnect the fuel rail from the fuels lines. Some on the forum have just set/tied the fuel rail out of the way during this work to avoid breaking the fuel line connection.
There are quite a few posts on this job on this forum and on the web, that were extremely helpful when I was considering this job. Feel free to PM me if you have any questions. Good luck.
No need to disconnect the fuel lines, just take the bolts out of the lower intake that hold the injectors in the plenum and on the drivers side of the engine you'll see a single bolt holding the lines at the engine, remove that bolt and swing the rail to the side. Don't disconnect more than you need to. There's a water pump bypass seal (oring), a heater pipe seal coming in by the thermostat area. Intake and exhaust pushrods are different length, don't mix them up! Exhaust rod is longer. Make sure the pipe running along the lower plenum isn't corroded where it enters the plenum on the side by the t-stat. If it is, replace it. If the head or plenum suface is deeply pitted, consider an appropriate epoxy or method to fill in the deep pit marks. This happens at the coolant ports only.
Yeah, just to be safe. I don't and I know that I'm risking an injury sometimes but the clock is not your friend in warranty work. Pull the fuel pump relay with the engine running, the engine will shut off, then crank it for maybe 10 seconds and fuel pressure will be very low or nonexistent. Don't forget to put the relay back in after you are done. Leave it out until you are done.
Are you talking about the stud that sticks up from the engine and connects to the corner of the coil pack mounting plate? I recall seeing somewhere that this stud could be removed, so when I did mine I took a good look at it and figured out that the stud was threaded on both ends. I was able to easily back the stud out of its position and then install the rear valve cover without any clearance issues.
You are correct, with the stud in the way it would be difficult to reach that one valve cover bolt.
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