The Jeep Guru – Page 54 – Jeep Performance Improvement Ideas

November 7, 2011

Fall crawl 2011

The XJ List returns to Harlan County’s Black Mountain Adventure park

My GMC Suburban was just not running right. It was down on power and had a severe stumble puling from stops and up the long hills on I 75 north of Knoxville. I had changed the distributor cap and rotor before leaving, but clearly there was still something amiss in the ignition system.

I arrived at the Harlan County campground about 30 minutes later that I had expected. However a quick text message to the group found them still having lunch at the top of the hill in the campground.

I got my park pass and checked into the campground. The drive up the hill to the campground was still a challenge towing the Jeep; but this time I made it without any assistance.

After, I unloaded and set up the tent, Wayne arrived and then we hit the trails. We were hoping to beat the rain. We managed to make it to the helipad and onto White Tail trail before the rain came.

We dropped down in to the ravine. Neal, Mitch and Adam took the rockier track While Wayne Jenny, Evan and I took the gravel track parallel to the boulder strewn path.

Soon the tricky downhill rock garden had Neal’s Cherokee lying on his side against the bank. A couple of guys pushed him back onto his wheels. Just a few moments later, Mitch laid his Wrangler on its side a little further down the trail. He was able to drive out of the flop with some encouragement from his spotters. No damage was evident on either rig.

The rest of us made a scary off camber scurry to join them at the bottom of the hill. The top of the hill had gotten slippery by this time due to the rain. At the end of the trail we found it blocked by banner tape. Apparently this trail was closed but we had seen no markings on the other end. We untied the tape and drove out onto 10 and put the banner back behind us.

We then did a little exploring on trail 11 and made our way over to Rail Bed. Jenny took the lead as this has now become her trail after the scary incident a few years ago. She made it look easy going over the slippery rocks all the way to the exit before getting stuck in the mud near the top of the exit. She got a quick tug and was out.

I tried to follow her line at the exit but I got mostly no where before burying my tires in mud. She tossed me a strap and pulled me to the top. Adam made it up behind me with lots of wheel spinning action. Mitch took what used to be the hard way out, but now that the rocks have moved around a bit, I wonder if I would not have been better off going the way he went.

We then made our way across the park back to our camp. By then the rain was hard and steady. Trail 45 was a slippery muddy mess but a fun way to end the day going back down to camp.

On the way down I kept hearing a dragging sound for the rear of my Jeep. It would go away when I accelerated but on the long downhill sections, it would just continue to get worse. I finally saw a place to stop and noticed that my left rear wheel was no longer centered in the wheel well. The noise was the tire dragging the rear fender opening.

I limped it on to camp. When I jacked it up and took of the wheel, I saw that the center pin of the leaf spring was sheared off. The main axle was free to slide back and forth along the main leaf. Using a couple a jacks and a large block of wood for a stand, I was able to get the spring pack apart and drive out the broke part of the pin.

We made a trip into town and luckily found a center pin. I also picked up an extra C clamp to help press the spring pack together. The next morning, I used a tapered pin to align the spring pack. I put in the new center pin and used the two C clamps to press the pack together while I tightened the new pin. I then used a ratchet strap to pull the axle back into place and align the pin with a hole in the perch. I then tightened the U bolts and was ready to wheel again. I did all this while most folks were still sleeping.

The other Kentucky folks showed up soon afterwards and we hit the trails again. We decided to do some exploring in the western part of the park where we really have never been. After the long climb up a very muddy trail 45 we regrouped at the Middle Fork Playground.

There were two high powered big tired buggies getting spanked by the slip and slide of trail 15. Adam could not wait to show them how it’s done in his XJ. He made it easily to the top and came back down one of the play hills.

We all made it up the slippery hill and regrouped in the small perch at the top of the first hill. Neal got hung up on about the third hill and those of us remaining at the bottom decide to take the bypass to speed things up some.

The two groups met back up at the end of trial 15. We then made our way out trial 12 to a wide spot for lunch. It had snowed on us here the last time I was there. This year is was just windy and cold.

We then paused at the Tough Truck challenge area. Josh made a run at the huge rock pile there. He made it across but somehow in the process of having all four wheels in the air at once got air in his power steering. We jacked up his rig and did a quick system bleed to get him going again.

We decided to head on west and see the sights. The leaves were beautiful as the sun broke through the fog. We stopped at 4 poles over look for a group photo. We also did a quick clean up of the area collecting a 30 gallon trash bag of bottles and cans.

We continued on west to the end of the park. Some how Neal spit out an axle shaft U joint so we paused for a quick trail repair. Unfortunately we had the trail completely blocked by out large group. He was nearly done with the trail fix when a group of ATV riders showed up. They were at first concerned over how long we would have the trial blocked but they were soon amazed at how fast we can swap an axle shaft as a group in the woods.

We then made our way up what looks like Kentucky’s version of Moab’s Lions Back. This trail is called Cliffhanger. It begins as a long gravely climb. Then it levels out and becomes a very narrow and steep rock ledge. There is an electrical tower right in the way so you have along the cliff to exit hence the name.

I was a little spooked as I drove to the top because I had not walked the trail like those in the front of the line had done. But I made it up with just a slight new pucker in the seat cushion.

After cliffhanger, we made our way across the park back to camp. It got dark on us along the way. The darkness added a little to challenge for us except for Evan who had no head lights. The darkness added a lot of challenge for him

The next morning we headed out to Lion’s Den. We had lunch and walked the trail. However rains had made entrance a mucky mess and Josh decided not to run. We then headed back across the park to Crawford’s cry. We had planned to run Your Turn but we got lost at a confusing intersection.

We headed out and got to watch so people on the new zip line fly across our heads. We eventually made it around to Crawford’s cry.

Neal headed up fist and Josh, Mitch and Adam followed. The climb was slipped in places and had large dry rocks in others. It was much harder than when I ran it a few years ago. Neal made it to the top but had trouble on the exit. There was no place to hook a winch line either. I walked back down and was driving Jenny’s Jeep up to use as an anchor when Josh found another way out.

Somehow in the maneuvering, Neal broke the main leaf in his right rear spring. As darkness approached we began to engineer a trail fix to get him out.

About the same time Adam popped a front axle U joint and had to back down. He also found he was out of fuel when he got back to the bottom. We had two trail fixes going at once.

I took my tool bag up to Neal and we decided to try using C clamps to hold the spring pack together long enough to get the XJ off the trail and down to the Evart parking area. With the springs clamped together, I left them to lead the rest of the group back to camp and get Neal’s tow rig.

Back at camp part of the group began dinner prep while Jenny and I took the long highway around the mountain to take Neal’s truck and trailer to him. It was well after dark when we got around, meeting Neal. But his rig had made it to the parking lot and he was able to drive it onto the trailer with the C clamps holding things in place. Our trail engineering fix had worked.

Once we were all back at camp, we dined on delicious fire cooked steaks and potato boats. We enjoyed the stars and conversation well into the night. Another excellent trip with the XJ list.

November 3, 2011November 1, 2011

Replacing the Idler Pulley on a Jeep Cherokee

If you get a strange chirping sound from the front of the engine in your Jeep Cherokee it is likely the idler pulley. These have a replaceable bearing but it generally easier to just buy the whole pulley with a new bearing installed.

To change the pulley, you will first have to loosen the serpentine belt. The belt is adjusted at the power steering pump. On most vintages, the power steering pump moves to adjust the belt. On the later vintages, there is an adjuster beside the power steering pump. Removing the air box makes access easier.

With the belt loose, remove the bolt in the center of the pulley. Most have a 15mm hex. Slip the pulley off and remove the sleeve from the center. In most cases you will reuse the sleeve.

If the pulley comes with a new sleeve, use it instead of the old one. Otherwise put the old sleeve in the new pulley. Bolt it back to the engine.

Reinstall the belt and tighten it up. I found the tension is about right when the belt will only twist 90 degrees between the power steering pulley and the water pump. It has to be pretty tight or it will slip when the AC is on.

November 1, 2011November 1, 2011

Replacing the steering box on a Jeep Cherokee

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.

October 31, 2011

Curing a soft brake pedal on a Jeep Cherokee

A soft brake pedal on a Jeep Cherokee can be very unnerving. The brakes are not exceptionally great on a Jeep Cherokee to begin with so when they are not working well, they can be downright scary.

The first place to look on a Cherokee is the adjustment of the rear drum brakes. If the shoes not adjusted right, then the pedal travel required to take up the slack will be enough to make the pedal feel soft.

To adjust the shoes, remove the rubber plug in the backing plate. Use a screwdriver or better yet a brake spoon to turn the spiked wheel. Turn it down to tighten the shoes. I usually tighten them until there is noticeable drag when turning the tire.

If the adjuster does not click when you turn the wheel, then the auto adjuster is likely not installed correctly. I see this problem often. The auto adjuster is operated by a cable the moves the adjuster wheel when the brakes are applied in reverse. The cable is routed over a small metal pivot point. Often the metal piece is not installed correctly under the spring and will allow slack in the cable. To fix, simply remove the spring and reposition the pivot plate in the hole and reinstall the spring. Just make sure the plate stays in place as you reattach the spring. That is the tricky part.

Also, if exposed to road salt, the adjuster screw may seize. Free it up with a rust dissolving oil like PB blaster or ATF. Coat it with grease when re installing to help prevent it seizing.

If the rear brakes are adjusted properly ands the pedal is still soft, you may have air in the lines or a leak. Check the rear wheel cylinders for evidence of leaks. Look for traces of fluid inside the brake drum. In the front, look for fluid around the calipers.

If you still have a soft pedal then you will need to bleed the brake system to purge any air. Air can get in if the master cylinder has ever run dry or if a brake line has been removed for any reason.

I prefer to use a pressure bleed system to bleed the brakes. I find it gets air out faster and I can do it without an assistant. I don’t like using vacuum bleeders because I have found that they can pull air in past aging wheel cylinder seals. If the seal are new this wont be a problem but old ones can allow in air during a vacuum bleed even if they don’t leak fluid out. The old “pump and bleed” method works if you have an assistant but is slower than a pressure bleed.

One last are to look at if you continue to have a soft pedal after checking all of the above is the front brake calipers themselves. Some Jeep calipers use a phenolic piston. The plastic in the piston can break down with heat and start to crumble. If the piston is breaking it may flake off a little each time the pedal is mashed.

Often the brake pedal firmness fades slowly and you get accustomed to it. Once a firm pedal is restored, you may be surprised at how well your Jeep stops and how easy the brakes are to modulate.

October 28, 2011October 28, 2011

Jeep Cherokee Check Engine Light Codes.

On the 91 to 96 Jeep Cherokees the ECU codes are accessible by watching the Check engine light blink on the dash. You cycle the key on and off three times leaving it on but not starting the Jeep. The codes will begin to flash on the dash light. Count the flashes and note the pause between flashes. For example the first code will usually be a 12. The light will blink once then pause and then blink twice more. The last code is always a 55.

Below are the instructions from the FSM on how to get the codes. Below that is the chart of what the codes mean. This chart was taken from the 94 FSM but all the HO engines will be similar.

ACCESSING DIAGNOSTIC TROUBLE CODES
A stored Diagnostic Trouble Code (DTC) can be displayed by cycling the ignition key On-Off-On-Off-On within three seconds and observing the Malfunction Indicator Lamp. This lamp was formerly referred to as the Check Engine Lamp. The lamp is located on the instrument panel.

11 * No Crank Reference Signal at PCM No crank reference signal detected during engine cranking.
12 * Battery Disconnect Direct battery input to PCM was disconnected within the last 50 Key-on cycles.
13 ** No Change in MAP From Start to Run No difference recognized between the engine MAP reading and the barometric (atmospheric) pressure reading at start-up.
14 ** MAP Sensor Voltage MAP sensor input below minimum acceptable voltage.
or
MAP sensor input above maximum acceptable voltage.
15 ** No Vehicle Speed Sensor Signal No vehicle distance (speed) sensor signal detected during road load conditions.
17 * Engine is Cold Too Long Engine coolant temperature remains below normal operating temperatures during vehicle travel (thermostat).
21 ** O2S Stays at Center Neither rich nor lean condition detected from the oxygen sensor input.
or
O2S Shorted to Voltage Oxygen sensor input voltage maintained above the normal operating range.
22 ** ECT Sensor Voltage Engine coolant temperature sensor input above maximum acceptable voltage.
or
Engine coolant temperature sensor input below minimum acceptable voltage.
23 ** Intake Air Temp Sensor
Voltage Low Intake air temperature sensor input below the minimum acceptable voltage.
or
Intake air temperature sensor input above the maximum acceptable voltage.
24 ** Throttle Position Sensor
Voltage Throttle position sensor input above the maximum acceptable voltage.
or
Throttle position sensor input below the minimum acceptable voltage.
25 ** Idle Air Control Motor
Circuits A shorted condition detected in one or more of the idle air control motor circuits.
27 * Injector Control Circuit Injector output driver does not respond properly to the control signal.
33 * A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch relay circuit.
34 * Speed Control Solenoid
Circuits An open or shorted condition detected in the Speed Control vacuum or vent solenoid circuits.
or
Speed Control Switch Always Low
Speed Control switch input below the minimum acceptable voltage.
or
Speed Control Switch Always High
Speed Control switch input above the maximum acceptable voltage
35 * Rad Fan Control Relay
Circuits An open or shorted condition detected in the radiator fan relay circuit.

41 ** Generator Field Not
Switching Properly An open or shorted condition detected in the generator field control circuit
42 * Auto Shutdown Relay
Control Circuit An open or shorted condition detected in the auto shutdown relay circuit.
44 * Battery Temp Sensor
Volts out of Limit An open or shorted condition exists in the engine coolant temperature sensor circuit or a problem exists in the PCM’s battery temperature voltage circuit.
46 ** Charging System Voltage
Too High Battery voltage sense input above target charging voltage during engine
Operation
47 ** Charging System Voltage
Too Low Battery voltage sense input below target charging during engine operation.
Also, no significant change detected in battery voltage during active test of generator output.
51 ** O2S Signal Stays Below Center (Lean) Oxygen sensor signal input indicates lean air/fuel ratio condition during engine operation.
52 ** O2S Signal Stays Above Center (Rich) Oxygen sensor signal input indicates rich air/fuel ratio condition during
engine operation
53 * Internal PCM Failure
Or
PCM Failure SPI Communications PCM Internal fault condition detected.
or
PCM Internal fault condition detected.
54 * No Cam Sync Signal at
PCM No fuel sync (camshaft signal) detected during engine cranking.

55 . N/A Completion of diagnostic trouble code display on the Malfunction Indicator Lamp (Check Engine Lamp).
62 * PCM Failure SPI miles not stored Unsuccessful attempt to update SPI miles in the PCM EEPROM.

63 * PCM Failure EEPROM
Write Denied Unsuccessful attempt to write to an EEPROM location by the PCM.

* Check Engine Lamp will not illuminate at all times if this Diagnostic Trouble Code was recorded. Cycle Ignition key as described in manual and observe code flashed by Check Engine lamp.
** Check Engine Lamp will illuminate during engine operation if this Diagnostic Trouble Code was recorded.