XJ Cooling

OK, I know this is well traveled ground,but after searching the archives, I still have a couple of questions. On the 3rd while heading up to my friends cabin for the 4th, my 1996 XJ overheated and started leaking coolant from around the water pump. I limped it back to my parents driveway where it awaits new parts. I have a Hesco water pump and a GDI three core rad. on the way. Tommorrow I am picking up some new hoses and a new thermost. I figured that if I had to tear into the system, I might as well do it all. Is there anything else I will need, or should replace? I am also curious about what kind of coolant i should use? Any particuar brands that are better than others? Also, is there anything that I should look out for as I undertake these repairs? Thanks for any info.

Add an OEM Jeep pressure cap, same with the thermostat, go OEM for that too. Don't use tap water, use distilled water. Also consider replacing the fan clutch.
Before disassembly put in a back flush kit from prestone, you install it in the return hose for the heater, add some flush and flush and back flush the system to get all the old coolant out, make sure your heater is turned on hot to flush that also.
Make sure to burp the system while/after you add coolant, remove the overlfow bottle, drain it, clean it out then reinstall it. Once you have it all together, dump a gallon of coolant in then add a gallon of distilled water. Mix the remaining gallon of coolant and distilled water into the empty coolant jug, that way you will have two 50/50 mix jugs. Once you start to top it off with the XJ's nose facing uphill keep the coolant level where you can see it, while there is air in it it will look like fizzy green soda, thats the air, let it run till all that is gone. The refill and burping will take about 30-45 minutes, add new coolant to the cold mark on the overlfow bottle and with the engine running, coolant right up to the radiator neck put the cap on, shut it off and let the expansion bottle take the rest of the air out.

Normally, in an overheat it should blow out from the overflow/recovery bottle, or maybe the radiator cap. So what you're actually telling us is that your water pump bought the farm.

Personally, I wouldn't pay Hesco's price for their water pump when the factory unit or a NAPA replacement is less money and plenty good enough for the job, but you've already ordered it, so that's moot. As long as you're "doing" the cooling system, I would also replace the fan clutch and the thermostat. Get an OEM 195-degree t'stat -- the factory ones are the only ones with the check valve in the flange, and that helps "burp" the system.

While you have the fan belt off I'd replace the Idle pulley which you should pick up at any parts store for less than $15. You also may want to inspect the bearing for the mechanical fan clutch. At 135,000 I replaced both of these while I had the water pump off, both bearings were rough. I am not sure when they changed the fan belt routing but my fan bearing was part of the AC compressor bracket. I had to buy the Assy for $75 to get a new bearing, but then I also got a new mount.

I'd also install a new fan belt. I run the goodyear gator back and it very quiet. Go to napa and buy the Kricket II belt tension gauge. The tool is less than $20. If you tension with the water pump this gauge will make sure you get the belt with the right amount of tension. On my 88 XJ the tension for a new belt was 180-200 lbs, used 140-160 lbs.

I like OEM gaskets so while your at the dealer pick up a water pump gasket. It comes with RTV preapplied so no need to buy any RTV. The thermostat should come with a gasket. The thermostat gasket is less than $1 and the water pump gasket was around $4. Always good to have a spare on hand, I ended up with 2 of each from the dealer plus the fel-pro versions. I liked the look of the OEM gaskets over the fel pro or the one Hesco provided with the pump.

The OEM water pump gasket comes with instructions on what the bolt torques are by model year. I recall there are two values give and both are less than 20 ft-lbs. If you don't have a torque wrench it time to buy one.

I also agree on using distilled water, and replacing the fan clutch. I ended up at carquest to get a clutch that had the same exterior deminsions as the OEM unit. AC delco make my OEM clutch, not sure who was the supplier by 1996.

I recommend you replace the heater hoses as well as the radiator hoses. Look in the archives for the CraigH heater flush. He uses two pieces of hose, one 5/8 and one 3/4 inch, attached female hose fittings to one end then then slipped them over the heater core nipples. He then ran water forward and backward until he got clean water. I found 4 ft lenghts of hose worked for me, I collected the water in buckets so I could inspect it. I also found hot water did a good job. I used the clothes washer faucet to get hot water. Also try to use a 5/8 or larger garden hose to get the water to the vehicle. I tried it with a 1/2 inch hose and did not get enough "flow".

And don't try to pull the old heater hoses off the mounting bosses, just slice them with an exacto or other razor knife. If they have been on there a while you stand a good chance of breaking a fitting on the heater core and you don't want to do that...