So today I finished up replacing my water pump and thermostat as so many of us have done, will do, or are considering doing it. I have never changed a water pump ever in my life until now, but I did it, and it wasn't as painful as the estimate to replace it from the dealership (or any other shop for that matter). Here's my two cents of the whole ordeal to add to all the other information on what to do.
-I rented a 36mm fan wrench from Autozone and the "whack it a couple of times to loosen the fan nut" didn't work for me. So, I used a strap wrench around the water pump pulley to hold it still and the fan wrench to get the nut off.
-I removed the thermostat housing and the lower portion of the mating surface had quite a bit of pitting and dimples so I decided to replace it since I wasn't sure the gasket would "seat" with this contour. The housing does not come with a gasket, neither does the thermostat, but a tube of RTV costs just as much so I got the gasket too with the pump and parts. (I went with OEM, I agree that I didn't want to chance it with cheap parts)
-I used a razor scraper to shave the surface clean, then used a Dremel hand tool and a wire wheel to clean more, followed by the Dremel with an abrasive wheel which looks more like one of those Scotch Brite abrasive cookies and that really made quick work of all the old gasket sealant to a nice shiny surface. I then wiped clean with brake cleaner.
I stuffed the holes with aluminum foil at first, but this was kind of stiff, so I just used a rag to keep the dust and chunks out.
I used RTV with my gaskets. I know this has been contested in every way, but for me and my first pump, I just didn't want to take that chance. At first I thought about doing it dry just like the FSM says, but the gasket is loose and you have to drive the water pump with the gasket on it around the pulleys and place it vertically onto the engine block. The gasket sits around a "lip" on the pump and I was worried it would shift or slip resulting in a leak. So, I first started using the Permatex high tack gasket sealant and that was just a lumpy sticky mess which gave me no confidence so I abandoned that idea. Next was the Permatex water pump RTV which has a gray color and resembles the Mopar RTV. It's thicker than other RTV sealants I have seen in the past. I applied the sealant to the gasket like butter on toast, real thin, smeared film and it stuck the gasket in place during mounting. I watched the mounting surface as long as I could as I was putting it on the engine to make sure it didn't slip or slide out of position. I then tightened the five bolts to torque in a star pattern and a very small amount of RTV squeezed out, like 1/16th of an inch which was reassuring to me it was seating nicely. I then let that set up for about 3 hours. It says overnight, but I was in a hurry.
-I put the thermostat in with the little hole at the top and made sure I put the thermostat in the recess of the engine mount. The gasket was done in the same way. Same thing, a very fine line of silicone squeezed out.
-I then replaced the Serpentine belt and started the engine without the fan since I wasn't sure if I was going to have a leak or not. I waited until the top hose was warm telling me coolant had circulated. No leaks so I finished the assembly (after the engine cooled off)
_ I topped off the coolant, replaced the fan, and started it up again and let it run. Here's where my fun began.
_ I backed my Jeep onto my driveway so I could clean up my mess in my garage and let it run and when I went to check the thermostat it read 260 and in the red! I shut it down and began to retrace my steps for a mistake. I frantically went online to search "Jeep TJ overheating after water pump replacement" and read about "burping" the coolant system. Completely made sense and I was hoping it was this simple. I went back out to my Jeep and the coolant overflow bottle I had filled before was completely empty which told me I was on the right track since the air had been displaced by this coolant. I removed the radiator cap with a bunch of rags over it so I would not take a chance getting sprayed with hot coolant and fired up the Jeep again. I kept adding coolant and watched it flow by until I could not add any more. After that, the dash temp gauge showed just under 210 which is where it was before the pump was changed. *Whew*. So, long story short, for you first timers, watch out for that air otherwise you may have to be ready to change your underwear like I did.
-I drove around for a while afterwards to get the engine and coolant nice and warm, and up to pressure so I could test the gasket and when I came back, no leak, and the coolant bottle still held the same volume so it looks like all the air is out.
In the end, it wasn't so bad afterall and I would do it again if I had to, but maybe after a few thousand miles.
The dealership quoted me over $450 for just the water pump and labor and another $100 plus for the thermostat portion. I did the same for less than half that in parts, time, greasy hands, and pride.
Again, my 2 cents.