Car repair – Page 52 – The Jeep Guru

December 13, 2010December 13, 2010

Ball Joint Replacement Jeep Cherokee XJ

This weekend I replaced the driver’s side ball joints in Jenny’s Jeep Cherokee. Ever since our last trip to Harlan, she has had a very loud and very annoying creak in her Jeep when she turned the wheel.

At first I thought it was the track bar because there was some slop at the frame end joint. Also the track bar bracket was loose where it mounts to the body. However with both of these problems corrected, she still had a creak.

It took so me time but we eventually tracked it tot eh ball joints. Most likely the lower joint because that one does not have a grease fitting. To find the squeak, I had her turn the wheel back and forth while I listened underneath. I could tell it was coming from the knuckle. I put my hand on the knuckle and could feel a vibration when it made the noise.

Using the procedure I wrote in the Ball Joint Replacement article, we replaced the drivers side ball joints. I used the hammer more this time and managed not to bend my Harbor Freight Ball Joint press.

With the wheel back on the Jeep is much quieter. There are still some noises but these are more in the normal range for a lifted Jeep XJ with well over 200,000 miles.
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December 7, 2010December 7, 2010

Power Steering Pump – Jeep Cherokee

My power steering pump started growling at Harlan. When I backed my Cherokee out of the barn last week, there was a huge puddle of power steering fluid on the floor. At first I was not sure it was from my Jeep but after cleaning it up and parking the Jeep back inside again there was another puddle of fluid.

While testing the new trails Saturday, I lost all steering assist for a moment and tagged a tree. I decided to put Scuffy away for the day and let Princess play by her self.

I checked the lines and the reservoir for leaks and found none. It must have been leaking through the pump seal.

I have a 94 parts Jeep but the part number for the power steering pump is different for the 88. I looked at the pump and it appeared to have the same mounting bracket. The reservoir is visibly different but the pump itself looked the same. But they have different part numbers.

In the process of removing the pump from the parts donor XJ, I broke off the return nipple. It was very cold and the hose stuck. The brittle plastic snapped before the hose slipped off.

I removed the reservoir from the 94 pump and inspected the connection point. It mounts in a hole sealed with an O ring. The tank is held on by a couple of tapered clips that come off easily with a hammer and punch.

I removed the pump from my 88 Jeep and noticed that the mounting bracket was exactly the same. The pressure hose looked the same. Only the routing of the return hose was different.

Since the donor reservoir was broken anyway, I decided to see if the tanks would swap. I removed the tank from my old pump and saw that it had the same O ring connection. I simply installed my old tank on the donor pump. I even used the bracket from the donor since it was easier to leave it assembled to the pump.

With it all bolted back up, I filled the reservoir with fluid and started it up. There seem to be no leaks. There was a bit of fluid slung off the belt but I hope that was from the old leak. I will give it a full test run later.

I was very happy to have saved $170 that a new pump would have cost. I was also happy not to have to remove and replace the pulley.

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December 3, 2010December 3, 2010

How To Replace a Leaking Rear Wheel Cylinder in a Jeep Cherokee

The rear drum brakes on Jeep Cherokees are generally reliable and long lasting. While swapping to disk brakes is a popular modification, the rear drums do a fine job of stopping when they work properly.

One common problem as the brakes age is that the wheel cylinder leaks. The wheel cylinder has two pistons that press out on the brake shoes when the pedal is depressed. The two pistons have rubber cups on them that will wear with age. Also, water can contaminate the fluid and cause the lining of the cylinder to rust.

There are several different wheel cylinders used so make sure you get the proper replacement before disassembling the Jeep. The cylinder for the 9” brakes is different from the one for the 10” brakes and the one used for antilock brakes is different from the one used for non antilock.

Begin by lifting the Jeep and supporting the rear axle. Remove the wheel and tire.

Using a 3/8” line breaking wrench, loosen the brake line where it connects to the wheel cylinder. If the line is stuck, try tightening it a bit before loosening it. Heat can help if it is severely stuck. Use care not to damage the metal line. Use a pan or a rag to catch the brake fluid that drains out.

Remove the two 3/8 headed bolts that hold the cylinder to the backing plate. Remove the brake drum. Loosen the brake shoes slightly if necessary.

Using a brake spring tool, remove the two upper brake shoe springs. Pull the front shoe slightly forward and slip the wheel cylinder out around the axle flange. Clean up and fluid that had leaked into the brake drum.

Slip in the new wheel cylinder. Install the two retaining bolts. Reseat the front brake shoe. Replace the springs using the other end of the brake spring tool. Take care to ensure the cable for the automatic brake adjuster is routed correctly and has not fallen out of place while the tension was off.

Reconnect the brake line. Reinstall the brake drum and adjust the tension.

Add brake fluid to the master cylinder to replace what drained out. Bleed the brakes by having an assistant depress the brake pedal while you open and close the bleeder screw.

With the bleeder closed, have the assistant pump the pedal a few times and then hold it depressed. Open the screw and allow fluid to come out. Close the screw and have the assistant repeat the process. Repeat the process and have the assistant note the firmness of the brake pedal as you observe the amount of air in the expelled fluid.

Once the fluid runs clear with no air, tighten the bleeder screw and install the protective cap. Reinstall the wheel and tighten the lugs to the proper torque. Lower the Jeep and top off the master cylinder before driving.
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November 21, 2010November 21, 2010

Torque Converter Lockup troubleshooting – The Red Jeep Saga

Scott’s almost has the red Jeep ready for paint. But there has been one nagging problem that he wanted to resolve before he put in the effort to paint the truck – the transmission seemed to refuse overdrive and the torque converter refused to stay locked up.

At first the trouble was intermittent. It was especially frustrating that when I drove the Jeep, it shifted fine but when Scott drove it, it would refuse to stay in forth and the converter would not stay locked.

For those of you new to this story, this is a 1989 Jeep XJ Cherokee. It was bought for parts with a burned up wiring harness. Scott has put it back together and it runs and drives better than any other Jeep in our fleet – except for its weird electrical problems that occur from time to time.

Scott first tried swapping the throttle position sensor. No change. Next he tried swapping the whole transmission computer. No change.

We tested the resistance across all the transmission control solenoids. All were within spec.

Next we decided to use the diagnostic procedure for the later model Jeeps even though this is a Renix Jeep and uses a different transmission computer. It does however have the same model of transmission, the reliable Asin AW4.

We test-drove the Jeep with the transmission computer unplugged. It worked exalt as expected with first gear only in the 1-2 position, 3rd only in 3 position and OD only in D position. Of course no converter lockup is expected with the computer disconnected.

Next, I rigged up a jumper wire to test the converter lockup. I probed the white wire to the solenoid and the yellow power wire to the computer and made a jumper and had Scott drive us down the road. As I connected and disconnected the jumper we watched the rpms jump and we could feel the converter locking up. So it worked mechanically. Just the computer was telling it not to lock.

This test confirmed my earlier suspicions that the Transmission was actually shifting into over drive and the converter was locking for a second and then as if commanded by the computer it was unlocking and sometimes shifting back to third gear.

Next we brainstormed things that would cause the converter to unlock and read more in the manual about how the converter worked. We found that pressing down on the accelerator should unlock the converter as well as stepping on the brake.

As these two circuits are very different we had to resort back to the older manual with its less specific wiring diagram. We saw that a blue and yellow wire was supposed to carry the brake signal trigger. Having already changed the throttle position sensor we decided to work on the brake circuit first. Inspection of the brake light switch showed only pink and black wires. We took another test run and found that if the brake input wire was grounded, the torque converter would indeed lock up. This test confirmed our theory of the brake input being the trouble.

The wiring diagram was less than helpful has it simply showed the bleu/yellow wire going through a switch to ground. It gave no clue as to the physical location of this switch.

Scott crawled under the dash again and searched until he found the blue/ yellow wire. There was a second switch on the brake pedal above the brake light switch.

We probed the switch and found there was no change in it as the brake pedal was depressed. The switch indicated that the pedal was down all the time.

He pulled the switch out and we found that it would work intermittently out of the Jeep. So I took the switch apart and cleaned it with contact cleaner. Once back together, it worked reliably.

Scott reinstalled the switch and adjusted it to properly indicate when the pedal was depressed. We reattached the original transmission computer and buttoned everything back up.

A tryst drive showed that it work just as it was supposed to. So far the transmission continues to operate properly. A simple solution to a problem that had frustrated Scott for a couple of months now.

November 18, 2010November 18, 2010

How to make your Jeep Last while enjoying it off road

Jeeps are huge fun to play with. And the best place to enjoy a Jeep is in the dirt mud and rocks. However use in these environments can take a toll on the Jeep if it is not properly prepared and maintained.

Proper preparation is essential to making a Jeep last off road. While Trail rated Jeep vehicles like the XJ Cherokee and Wrangler are very capable off roaders in stock form, there are some simple modifications that will help them last even longer.

One of the most important preparations is to have the proper tires for the environment. It you are going to be in mud, rocks or dirt, you need a strong tire with deep tread. Having a tie with high void area like a Mud Terrain tire helps get even more traction in all off road conditions.

By having good tires, you will be able to approach obstacles with less momentum and reduce stress on the suspension and body work. Having the right tire and not getting stuck go a long way to improving the overall reliability of the Jeep.

Using lower air pressure in the tires when off road will also improve reliability and longevity. Reduced air pressure will allow the tire to conform to the terrain aiding in traction. Lower air pressure will also allow the tire to flex more over obstacles that might otherwise puncture the tire.

The next area to consider is the armor. Rocker rail protection is critical on Jeep Cherokees. The pinch seam on the bottom of the Cherokee is easily susceptible to damage by rocks and other off road obstacles. If the pink seam is damaged, the overall body structure can be weakened. Rocker protection can be simple or elaborate. There are many styles available for sale or they can be easily fabricated with minimal welding skills.

Protecting the under carriage is helpful as well. Factory skid plates were available and provide adequate protection for most off roading. There are also many versions of skid plates available in the aftermarket as well as self fabricated options.

Lifting the vehicle will also allow more clearance between obstacles and the bottom of the Jeep. Lifting also allows larger tires to be fitted so that both traction and clearance are enhanced at the same time. Being able to drive over more obstacles will help your Jeep last longer in off road service.

Even when your Jeep is properly prepared, proper maintenance is important to its long life. The front suspension and steering joints are fitted with grease points so that dirt and water can be flushed out after off road adventures. Use a standard automotive grease gun to force fresh grease in to the joints and to flush out contaminants that may have collected there after each trip off road.

Also, if there is a chance that water could have contaminated the differential fluid or transmission fluid, change these fluids as well. At minimum, follow the recommended change intervals in the owner’s manual.

Keeping the seals in good shape will help keep vital fluids in and water and dust out. Replace oil and grease seals when there is any evidence of leakage.

Despite your beset efforts to keep parts lubricated, moving parts such as universal joints and tire rod ends will wear out. Inspect these parts frequently and replace them when they show signs of wear. If these parts fail, they can take out other expensive parts or leave you in a very dangerous position off road. Inspect and maintain these joints before and after each off road trip.

Dirt is very abrasive and will be the most damaging element of off roading. Therefore after each trip off road, thoroughly clean the Jeep including the under carriage. Remove dirt and mud that accumulates on the suspension parts to keep them moving freely. Keeping the parts clean will also aid in inspection so that wear can be noticed more easily.

Driving style is also a factor in how long a Jeep will last off road. Knowing how and when to use momentum to get over obstacles is critical to safe and damage free off road driving. Learning from more experienced drivers and practicing on smaller obstacles will help you gain the skills needed to safely drive your Jeep through any conditions.