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After both the block and thermostat housing surfaces have been carefully cleaned, insert the new thermostat and position the new gasket. Place the thermostat housing over the gasket and tighten the housing bolts to 15 ft. lbs. Reattach the heater hose to the housing and if you removed it, the other heater hose going to the block.
If you removed the serpentine belt, now is the time to install it and adjust the idler pulley. I set the tension on mine as close as I could determine to the way the old belt was prior to removal.
Scott gave me a good tip and I will pass it along. Take a box knife and cut up the box that the radiator came in. Take a piece of cardboard and cut it to be the same width as the radiator. Push the fan shroud back as far as it will go and then slip the cardboard in front of the shroud. Now, when you slip the radiator into place, the shroud will not dig into the radiator core fins and bend them. Thanks Scott for the tip! It worked very nicely. Now, slip the radiator into position. This is another place where having a friend around will come in handy.
Note: Some distributors carry one radiator for both auto and manual transmission TJs. (cheaper to stock just one model that fits both) The radiator for an automatic has a pair of 3/8" fittings in the bottom of it where the automatic transmission fluid is routed through the bottom of the radiator to get cooled. If the new radiator that you purchase has a pair of fittings on the bottom, and you have a standard tranny, don't worry....get a couple of 3/8" plugs and screw them into the holes. This will keep "junk" out and just in case you should ever decide to get an automatic tranny, you'll already have the necessary radiator for it.
After tightening the 6 mounting bolts and reinstalling the fan shroud (four bolts there), connect both the upper and lower radiator hoses. Give your handiwork a once over just to make sure you didn't miss anything (be sure the petcock on the bottom of the radiator is closed). I poured a full gallon of antifreeze into the radiator and followed it with a gallon of distilled water (well, almost a gallon....I put the last pint of it in the overflow bottle and then topped the bottle off, up to the cold mark, with antifreeze. Be sure to use distilled water. You do not want, nor need, the minerals from regular water plating out on the inside of your cooling system. (albeit, you will have some in your system if you flushed it with the garden hose as I did....well, we try the best we can!)
After running the vehicle for about 5 minutes (with the radiator cap in place), I carefully opened the temp sensor. Scott said I should see some air bubbles when I did and sure enough, it burped a couple of times. He said this helps get the air out of the water jacket and prevents hot spots in the engine. It sounded good to me so I'll pass it along here.
That was it. I cleaned up my tools and put them away and then took Lady out for a couple of miles so she could get the cooling system up to pressure. I drove back to Scott's, opened up the hood, and then checked the system for any signs of leaking. Everything looked good so we started working on Les' Anti-Rock bar install.
I hope yours goes as well as mine did!