Replacing LIM Gaskets on 3.1L anything else?

I own a '97 GP which I bought with 5K miles. Had the LIM gaskets replaced once under warranty, another time with the plastic Fel-Pro's @ about 100K and now I have 175K and the coolant level keeps going down so I'm planning on installing the Fel-Pro PermaDry LIM gaskets.

While I'm doing this work I'm planning on replacing all the coolant hoses (AC Delco), spark plugs (Denso Iridium), valve stem seals (Fel-Pro), injector o-rings (AC Delco) and thermostat (AC Delco).

Anything else recommended to replace while I'm in there? I don't necessarily like to replace things just for the heck of it, but at the same time, with 175K I'm sure there's some tired components that would be good to replace to get another 175K miles out of the car.

The car has been maintained very well. Mobil 1 10W-30 has been in it since purchased back in '97. It runs strong and gets ~24mpg commuting and ~30mpg on highway trips.

Thanks for your input!

No takers on this? Must be some on vacation... lol A friend and I just replaced my UIM and LIM gaskets and we replaced the valve cover gaskets while we were in there. I have a 3.8, not sure what's involved with a 3.1.

I have a 3.8 in my Bonneville. When I did the Dorman UIM kit and LIM gaskets, I looked at/replaced the following. This was at 80K.

Replaced serpentine belt
Replaced both bearings and brush set in the alternator (drive end bearing was chirping a bit)
Checked water pump for excessive play
Replaced belt tensioner pulley (had a little too much play)
Cleaned throttle body (it was really dirty)
Replaced coolant elbow at LIM
Replaced plugs (like you're doing)
Replaced plug wires
Replaced PCV valve (came in the kit)
Took a long look at all vacuum lines and rubber juctions. Dry rot, etc.

Wished I had thought to get a thermostat. I'm doing a coolant flush and hose change in the very near future. You're doing the hoses now. Very wise!

Yes I also replaced my serpentine belt. Replaced coolant elbow at LIM which pretty much goes without saying when replacing the UIM LIM gaskets. Cleaned throttle body also. I already had replaced my upper coolant hose so this was a excellent time to replace my lower coolant hose. I'm surprised it lasted this long.. Even though we didn't notice any leaks around the valve covers, we went ahead with that anyway. With my luck, they would have started to leak by now anyway if we didn't..

Also change the oil pump drive o-ring seal (it's basically a lower distributor shaft with the top cut off). It's located in the block under the throttle body area. Easy to get to while it's taken apart and a common oil leak on 2.8/3.1/3.4 GM engines. I also install a paper gasket from a Chevy V-8 (fel-pro part # 70194) for added insurance.

The Fel-Pro Permadry set comes with the valve cover gaskets so you don't need to purchase them separately. Just an added note, the 3.1's don't use the plastic elbows like the 3.8's do, so irrelevant on this engine (but a great tip on the 3800's). Use a wire brush to clean the lower intake bolt threads of any old threadlocker/grease/grime and then spray with brake clean to insure you got it all, then re-apply Loctite blue prior to assembly. This will insure the bolts don't work their way loose again as the torque value is low (12 ft/lbs on the outer short bolts, 89 in/lbs on the inner long bolts).

Lastly, I would also drill a 1/8" diameter hole in the t-stat flange to help purge air when refilling the coolant. I've never understood why GM doesn't add a jiggle valve to this t-stat like they have on the one for the 3800's. When installing, position the t-stat with the hole you drilled at 12 o'clock (as the 3100 t-stat mounts vertically not horizontally) so the air can escape while refilling.

Good luck!