How to replace the knock sensor on the Jeep Renix engine.
The knock sensor is used by the Renix engine control system to fine tune the ignition timing. If it hears knock it will back off on the timing a bit. It will run the ignition timing as far advanced as it can to get the most power and fuel economy.
My Jeep is equipped with a K&N air filter and intake tube so I don’t have an air box in the way any more. I loosened the power steering pump and moved the drive belt out of the way of the thermostat housing. I have done it without loosening the belt but it is much easier with out the belt in the way.
The later model XJs have the belt routed where it is not in the way. However, on an earlier XJ like my 91 the belt interferes with getting the bolts started back in the housing. I previously wrote about changing a thermostat on a 99 XJ.
I popped off the radiator and heater hose. I disconnected the temperature sender wire.
I then removed the two 1/2 inch head bolts and popped the housing off the block. I set up a pan under the Jeep to catch the antifreeze. I also laid out newspaper to soak up the splatters as anti freeze is very slippery on the floor.
I cleaned up the bolts and the housing using the wire wheel on my bench grinder. I then use a scraper and a scotch brite wheel in my drill to clean the block face.
I noticed that the new thermostat did not have a bleed hole in it, so I drilled a small hole in the flange. It is hard to bleed all the air out of a 4.0 if there is no hole in the thermostat. Most of the ones I have bought lately have a hole but this one did not. So, I made one.
Getting the new thermostat to stay in the block while setting the housing is always tricky. I knocked mine out the first time and only noticed it when the antifreeze started to run out as I was filling the system.
I put a dab of Permatex on the flange to get the thermostat to hang in place long enough for me to slip the thermostat housing in place over it. I used additional Permatex to make the gasket stick to the housing. I held the housing in place with one hand while I started the bolts with the other hand. I was able to get it all in correctly on the second try.
I tightened the bolts and left the hoses off until I filled the system. I then reattached the hoses and filled the radiator completely with anti freeze. I then put back the temperature sender wire.
I put the belt back on and started the engine. I checked for leaks and made sure the engine came up to the proper temperature. I let it cool and topped off the radiator with coolant. I enjoyed having a nice warm heater again this morning.
The steering box on a Jeep Cherokee rarely goes bad. Mine has over 345,000 miles on it. However, I recently changed one that had been damaged in an engine fire. These instructions will also help if you want to upgrade to a larger steering box.
Begin by removing the air box and electric fan to gain access. Remove the hydraulic hoses. The fittings at the box are 18mm. It may help to have a crow foot line wrench but I always make do with a stubby 18 mm open end.
Remove the bolt that secures the sector shaft to the box. It may not look like it, but the bolt has to come all the way out to release it from the splines. Use a pry bar if necessary to slip the sector shaft off the splines. Use some penetrating oil on the slip joint in the shaft if it seems like it does not want to compress. If you try to compress it and it sticks, the rubber joint at the top can be damaged.
Disconnect the pitman arm from the tie rod. You will need a tie rod puller to do this job. Be careful not to damage the rubber cup on the tie rod while removing it. Put some tension on the joint with the puller and then use a sharp strike with a hammer to free up the joint. Trying to pull too hard will likely damage the puller and not release the joint. A sharp blow from a hammer on the side of the pitman arm will pop it right out.
The box is held to the unibody by three bolts. These have 5/8 inch heads and are held in by thread locking compound. Use a long handle ratchet to get them out. There is an aluminum spacer between the unibody and the pump. Sometimes the bolts will seize in the aluminum. If the spacer breaks, you can replace it with a stack of washers on each bolt. Also, if using a larger steering box, you may have to space the box further away from the frame rail.
With eh bolts out you can lower the box down behind the sway bar. Be careful because it is heavy.
Removal of the pitman arm is difficult. Use the proper puller and possibly heat to remove it. If possible, get a replacement with the pitman arm already attached.
To reinstall, hold the box in place and start one of the bolts. It may be helpful to have an assistant hold the box from above while you align it and start the bolts from below.
Reconnect the tie rod and install the cotter key. Attach the sector shaft and install the bolt. You map have to use a hammer and lightly tap the end of the shaft in place. Alternately you can use a chisel to spread the coupling apart before attaching it to the steering box.
Reattach the hydraulic hoses. Lift the wheels off the ground and turn the steering from side to side. Make sure there is no binding. Fill the system with fluid and repeat the side to side motion. Start the engine and turn the wheels from lock to lock to purge the air from the system. Make sure the reservoir stays full of fluid while purging. It is common for the fluid to foam while purging.
If the pump sounds like it still has air as indicated by a growling sound when turning the wheel, turn to one of the stops and hold the wheel there for a second while the pressure relief opens. You will hear the valve open when you hold it against the stop. Repeat a couple of times to purge all the air.
Test drive the Jeep to make sure the steering is centered and has the proper feel. Adjust as needed.
When we got to the bottom of the hill on Iron Gap Road, we were faced with a creek crossing. Dropping down into the creek was challenging due to the spring that wet the rocks about half way down and by the off camber nature of the drop.
Saturday morning brought more rain as I added power steering fluid to Jenny’s Jeep and bled the air out of the system. Through the breaks in the drizzle, we had scrambled eggs made on Frosty’s grill.
Getting a slow start from camp we decided to make a leisurely run along the east ridge of the park to see the vista the group had found the night before. We headed up the other end of trail 15 out of Middle Fork. This trail starts of with a steep twisty climb before it follows the ridge out to the helicopter pad.
Just at the top of the hill, a place we spent way too much time at on our first trip to Harlan, there is now a very deep mud puddle.
Just as we were lining up to go through he puddle, Evan called on the radio that his Jeep was leaking transmission fluid and was not moving well. I pulled out a hospital cloth for him to lay on and he found that his control arm had hit the transmission lines and crimped both and punctured one of them.
It took a while, but we eventually gathered enough hose, clamps and tools for him to cut and splice the two damaged lines. We headed out again after he was repaired.
From there we made our way on to the Helicopter pad. We continued on the trail past the pad and drove up to the vista the guys had found the evening before. The view form there is spectacular! We enjoyed lunch there and posed the Jeeps for a group photo.
Next we made out way to Mason Jar. We decided to follow the new signs instead of the map thinking that they may have made a short cut to the entrance of Mason Jar that was not mapped. However, we were disappointed to find that the signs led us to the exit of Mason Jar. And Mason Jar is a one way trail!
Janice and several others decided to walk the short trail while some of us drove around to the entrance. At the entrance we saw a buggy on huge tires having a terrible time getting up the first obstacles. He would just sit there and use his big engine to dig out dirt at the bottom of the rocks. As we met the walkers, they told us of two wranglers that were broken down further up the trail.
Neal, Frosty and Josh elected to go ahead and run the trail while the rest of us decided to explore elsewhere. We loaded up every one into the back seats and cargo areas of our Jeeps and made the trip back to the exit of Mason Jar to pick up their Jeeps.
Form there, we went to Lions Den so that those who missed Thursday adventure could at least get a feel for what it was like. We watched a Wrangler on one ton axles crawl through but not without great difficulty.
From there we headed back to Middle fork to play on the hills there. We had just started up Running Board when the others caught up with us. Scott P made a run but ended up backing down.
We decided to head back to lower rock garden to play around more. After some time there we headed back to camp to enjoy the now famous steaks and potato boats around the camp fire.