Cherokee Heater Valve

Yesterday I had a nice opportunity to do some work on my car so I used it to replace my rusted heater valve. This valve simply redirects coolant through the heater core when the heat is on warming the air getting blown into the car. The old valve was very rusty and seized up. When the climate controls are set to cool air, vacuum is applied to this valve to close the valve shutting off the flow of coolant to the heater core. When you change to heat, the vacuum is released and a spring opens the valve. The old valve was rusted enough so that the vacuum and spring weren't strong enough to move the valve, but up until last winter I could manually move it with a pair of pliers. Recently it had gotten so bad I couldn't fully open the valve even with the pliers, so I wasn't getting as much heat as I should since the valve was half open. All the hoses involved were also looking rather nasty and probably needed to be replaced anyway.

Hot coolant flows from the manifold into the valve through the red hose. The vacuum motor (the dome looking thing) moves the valve so that it either flows directly out (the bottom black hose) to the water pump or through the firewall into the heater core and back out to the water pump.

This valve is pretty pricey new so I looked around and I was able to find a used one on ebay for a late 80's Wagoneer for $10. The new one is made of plastic, so it'll never have the rusting problem the original one did, and the ports are more conveniently located on the new one, so I can have shorter hoses at less awkward angles. The seller said even though it was used it didn't leak and worked perfectly; I was pleased to find out when it arrived that this was exactly the case.

This just shows you how the new valve works. There is a vacuum line attached to the top and when you slide the temperature control from hot to cold, it opens and closes the valve.

This is a shot of the lines in and out of the heater core.

This is probably the nastiest hose in the system. Notice all the green crap at the end? I guess it was leaking a little already.

It was really hard getting those heater core hoses off. Once I got them off though, I noticed that they weren't the same size. The top one (output) is ³/₄" and the bottom one is ⁵/₈". The new valve however only had ⁵/₈" connections on it. Then I took a closer look and realized that the water pump also had a ³/₄" hose on it. I guess that was the difference between the older Cherokee valve and the newer Wagoneer valve.

Luckily I was able to find a couple of these adapters that went from the bigger to the smaller size hose. I would've been up in serious trouble if I couldn't lay hand on these things. I needed 2 of them (from water pump to valve and valve to heater core) and of the 3 local parts stores I called only one of them had these in stock and they only had 2.

Having to use these toids put the new valve farther into the engine compartment, but I was able to position it so it wouldn't interfere with the distributor or the oil dipstick.

It took quite a lot of hose pieces and clamps, but it they were all necessary.

I didn't think to do some temperature tests before changing the valve, but now I get over 120° air, and I can actually adjust the temperature with the intended controls from within the car. When I went for a drive after getting this all together to test it, I started getting heat after just a couple minutes of driving when it used to take around 20 minutes to get any noticeable heat.

This job took a lot longer than it really should have, but at least there weren't any show-stopping problems. It took forever to get some of the hoses off because they and the clamps were probably 22 years old and I was trying to not damage things like the heater core connections. Then there was the whole hose size difference with an extra trip to the store.

Missing Some Oil

I changed my oil today when I got home from work. I'm usually pretty good about keeping on top of stuff like this, but as you can see from the pic below, I'm missing about 2 quarts! I knew I was a little low, it was below the 'add' line on the dipstick, but this kind of scares me after the fact. I didn't see any metal while I was pouring the old oil into the milk container, so I don't think any damage was done.

Advance Auto Parts is currently having a special on oil: you get 5 quarts of Mobil 1 synthetic oil (any weight) and a Mobil 1 filter for $29. AND if you have an entertainment book there is a $5 off coupon for any purchase over $25!

Jeep Fuel Problems

My Cherokee ended up needing a new fuel pump recently and the whole situation was rather inconvenient.

Back in August it failed to start for the first time ever when I went to drive home after work. It would just crank and crank. I poked around for a little while and figured the problem was fuel related. I had compression because the engine was cranking at its usual speed and I had spark because I pulled a plug wire off to test it (shocking the hell out of myself in the process). The only other thing required for that car to run is fuel. When you first turn the key to the on position the fuel pump is supposed to turn on for about one second and then turn off. I couldn't hear it turning on at all when turning the key. I took a look at the wiring, which all looked ok and checked the fuel pump relay which seemed to function properly, so logically it was a fuel pump. Since I was in Harley's parking lot on a hill I really didn't want to get into changing this part myself. The pump is inside the gas tank and not very easy to get at, especially with an almost full tank of gas.

I had the car towed to a shop I've used before for them to fix it. The next day they went to check out the car and it started right up! I talked to my dad who said from his experience fuel pumps tend to start getting weak and not able to keep up under high demand, like going up hill on the highway. He also said he didn't think they would start working again if they fail. So instead of spending $400 to replace a pump that was working at the time I took the car home.

Fast-forward to last week: I was driving home from work on 31F and just as I was passing the Wegmans in East Rochester my car seemed to lose some steam for a second and then came back. I kept going, but just as I crossed the canal entering Fairport the engine died completely. I can think of worse places to break down, but Church Street in Fairport is a busy road and at rush hour is even worse! Again I sniffed around for while and couldn't hear the pump turning on. I could hear the relay clicking on and off though, so I knew it was getting power. I climbed under the car and banged on the gas tank a bunch of times hopefully trying to shock the pump into working again. No dice. I had it towed to a local shop to replace the pump.

The next day when the shop went to look at the car, it started right up (surprise, surprise). I talked to the guy and told him all the diagnosing I did, and he said it sounds like a pump, but they couldn't guaranty that since they couldn't reproduce the problem. They ordered the pump from the Jeep dealer and four days later when it arrived it was the wrong pump! The dealer only had a listing for a mechanical pump and my car has an electric pump. Since the dealer didn't have a part, they got a cheap aftermarket one from a local parts place. They put it in and it died about 5 seconds after the car started. Then they put in a much more expensive Bosch pump which worked fine.

It kills me to spend this kind of money for something that I'm not 100% sure will fix it, but what choice do I really have? I can't keep driving it until it fails on the road leaving me stranded. With my luck it'll do that in some deserted area in the middle of a blizzard. I'm really going to be pissed if that thing dies on me again with the same symptoms. At least the shop that did it has a 1 year warranty on the part and the labor if it fails again.

I have the old pump and plan on taking it apart to see why it failed, I just haven't had time yet.

My poor jeep stuck on the side of the road :(

Broken Brake

I have a rather old car, a 1986 Jeep Cherokee. When you own such an old automobile, you have to be prepared to fix things that are going to break. The latest thing broken on my car is the parking brake. The brake got used every time I drove the car so it is nice and free and works perfectly (except when rolling backwards, but that's a design flaw), but the button on the handle for applying and releasing the brake broke off last week.

As you can see in the picture, the button just attaches to that rod to release the break. But I could deal with that if it worked without the button, but there needs to be tension applied via a spring to pull that rod out. If I latch on a pair of visegrips I can make the brake function properly by pulling on the rod as I engage it, and then just push it in to release it.

I did some research online about what to do and I came across a few posts on JeepForum mentioning a recall on XJ parking brakes. Apparently they had a habit of just letting go randomly. My brake hasn't done this, but if they're fixing it for free, who cares. I've called my local dealer twice and have yet to get a call back. They probably route all the recall oriented telephone calls to some dummy mailbox that never gets checked.

I've read about a few guys having success just using epoxy to glue the button back on (using duct tape to depress the button while it cures), which I might try if this recall thing doesn't pan out. I called around to a few parts stores and they all said I can either get one of those assemblies at a junkyard or a dealer. The dealer wants $200 for it, so if I can't find one in a yard maybe I'll just start carrying a brick around with me.

Vacation

A couple of weeks ago we took the long trip down to New Jersey to visit my family for a while. We usually take Rachelle's car because it's quiet and has air conditioning, but I needed to do some work on my car with my dad so we took the jeep. The ride down wasn't that bad. It was an overcast day and was actually a little cold, so the missing a/c wasn't a problem.

Rachelle took the train to Long Island to visit a couple friends there for a few days while I hung out at home.

My dad recently got a lift for use in his barn, so we were able to raise the jeep up to our level while working on it. It made everything soooo much easier not having to bend over for hours at a time. It looks like it would be tippy, but it's really pretty stable. We were able to climb a ladder and get in it without it moving much at all.

The main thing I needed to do to the jeep was replace the driver side front-axle universal joint. The old joint was making a terrible pulsating squeaking noise when ever the wheels were turned while moving. While we were at it, we found that the wheel bearing was going bad so we replaced that at the same time.

The other thing I really needed to do was replace the rear differential cover. The pinion seal is leaking a little (still), and the check/fill plug for the differential was completely rusted in place. The only way to check the fluid level or add any would be to remove the old cover and replace it with a new one. Below is a movie of how the differential works. It's kind of neat how they designed a way of powering both wheels while allowing them to spin at different speeds (like while the car is turning).

That's my dad doing his teacher-thing in the background explaining why you don't want the spider gears spinning since they don't have bearing.

86 Cherokee Wheel Bearing Replacement

The Problem

From 37 to 46 MPH a really annoying pulsating noise would rattle your brain. Then from 66 MPH and up an even louder high pitched hum would start. It was really annoying.

Possible Solutions

I could either pay someone to replace it, or do it myself and possibly learn something in the process. I called around and was told it would cost around $300 to replace the bearing. That is a lot of money just to get rid of a noise. I found the entire bearing and hub assembly was only around $65 from a local parts store, so I figured I would try fixing it myself.

Tools Needed

Pictured

• PB Blaster - I probably wouldn't have been able to get any of the bolts out without this stuff.
• LPS3 - for preventing the bolts from getting all rusted and corroded again
• 3-Jawed Gear Puller - for pulling the bearing/hub out of the steering knuckle
• Torque Wrench
• 1/2 Breaker Bar
• 1/2 Ratchet
• 36mm 6 point Socket - for the hub nut (borrowed from Advance Auto Parts)
• T45 Torx Bit - for the brake caliper pins
• 13mm 12 point Socket - for the hub retaining bolts
• 19mm 6 point Socket - for the lug nuts
• Pliers

Not pictured

• Jack
• Jack Stands
• Hammer

Procedure

The first thing was to break the hub nut loose. To get at the hub nut I had to first take the wheel off and remove the plastic cap from the center of the wheel. Then remove the cotter pin and the nut retainer from the end of the axle shaft. This allowed me to get to the hub nut to break it loose. It was supposed to be torqued to around 175 ft-lbs so I put the wheel back on and set the car back on the ground to prevent the nut form turning as I break it loose. The nut felt like it was only on at around 50 ft-lbs and came off without a problem.

After removing the wheel again I took the brake caliper off by unscrewing the 2 pins holding it on with the torx bit. The rotors were replaced on this car two years ago for inspection so the caliper came off really easily. Then the rotor, pads and clips. This gives you access to the bearing/hub assembly.

To remove the hub you have to remove the 3 12 point 13mm bolts from the back of the steering knuckle. You can only see 2 of them in the pictures above. Once they were juiced up they came out pretty easily too.

From what I read online and in the service manual the whole hub assembly should just slide out of the knuckle once you remove the 3 retaining bolts in the back and the hub nut in front. It didn't. It was pretty rusty and needed some serious persuasion to come out. I had to go back to the parts store and get a gear puller. Even with the puller I had to juice it up over a couple of hours and smack it around with a hammer and block of wood to get it out.

The knuckle looked pretty rusted when I finally got the hub assembly out so I used some sand paper to clean it up a little before putting the new assembly in.

New and improved, old and busted...

Before putting the new hub in I greased the splines of the axle shaft, the knuckle, and the new bearing side so it might come apart easier in another 120,000 miles if I have to do this again. Notice I have the brake shield on backwards in the picture...I didn't notice this until I had it all back together and tried putting the rotor back on.

Once I got everything back on (the correct way), I bolted the hub on and torqued the bolts to 75 ft-lbs. Then the clips and the inside brake pad went on. Then the rotor and outside pad. Then the caliper, torquing the pins to 20 ft-lbs. At this point I did a quick check of the brakes. I looked around to see if brake fluid was dripping from anywhere, thankfully it wasn't. Then I stepped on the brake pedal so the caliper would align itself correctly and to make sure I still had a firm pedal. The wheel went on next and then I put the car back on the ground to torque the hub nut. My torque wrench only goes up to 150 ft-lbs so that is what I used instead of the 175 the book recommends. Then I took the wheel off and on again to put the plastic cap back in. Lastly I went for a spin around the block to see if the noise is gone and to see if the wheel falls off. I'm going to drive it around town for a while and then re-torque all the bolts once everything has a chance to settle. And I'd rather a wheel fall off while I'm tooling around town than while going 70 MPH on the highway. We'll see.

Final Result

Instead of spending $300 I spent around $100 ($25 of which was the puller) and learned a lot about my car. I haven't been very comfortable in the past taking on big projects on my car, but I'm getting braver with each one. This was by far the biggest and most complicated, but I'm starting to learn that as long as I have the right tools and the book, I can probably do anything needed to keep this car functioning.

Cherokee Lean-Surging Problem

Status: FIXED!

This was by far the most irritating problem I've had with this car. The car was very mushy; it had no power and generally ran like shit. You hold the accelerator steady (with clutch in) and the RPMs bounced around. It was sometimes difficult to clutch out (the RPMs would suddenly drop when loaded) and when driving at any speed if you step on the gas the just didn't go anywhere. It struggled to keep up 35 MPH on a flat road.

This is how the car sounded when idling (at the exhaust pipe): exhaust.wav (142 KB)

Original Diagnosis - Vacuum Leak

Right from the get-go this problem seemed like a vacuum leak. All sorts of things on this car depend on vacuum to operate properly: power brakes, 2/4wd selection, climate controls and a bunch of other stuff you'd never think of. What confirmed this theory was spraying something flammable near the vacuum hoses at the intake manifold. I shot the hoses with brakleen and all of a sudden the engine would speed up and sound much better for a few seconds. Obviously the leaking hoses would suck the flammable brakleen in and it would make the fuel/air mixture a little richer. Even though the car did (and still does) have a little vacuum leak, it wasn't the root of the current problem

Secondary Diagnosis - Ignition

It was about time for new spark plugs anyway. I bought a new set of plugs, wires and a new distributor cap and rotor. Wasn't the problem.

Tertiary Diagnosis - Exhaust Restriction

Cat basically disconnected from exhaust pipe.

If you can't exhale as fast as you inhale, you're not going to be able to run a mile right? At the time the catalytic converter on the car was falling apart and making noise, so perhaps it broke up and clocked the pipe. So I unbolted the cat from the exhaust pipe and bolted it back on to the opposite side. This way the exhaust gas would completely bypass the cat and muffler. I went for a really loud spin around the block, and found the problem was still there.

Final Diagnosis - MAT Sensor

At room temperature this should be reading 3500 Ohms.

Over the couple months I was trying to fix this problem I came across a sensor that wasn't reading correctly. It was a temperature sensor mounted in the intake manifold that monitors the air temperature and adjusts the fuel mixture accordingly; the colder the air the richer the mix. Even though I found this problem pretty early on, I was unable to find a replacement. The problem was that everyone had their own name for this part, some (Jeep) called it a MAT sensor and some (Advance Autoparts) called it an air charge temperature sensor. I was finally able to find a replacement and the car was better instantly.

Magnetic Oilpan Heater

Early in 2004 the Cherokee began getting difficult to start. It would be very lumpy when starting below 20°F. After sitting for a few minutes (while trying to keep RPMs around 2500), the engine would warm up a little and start running right. In hindsight I can see this problem was actually my lean surge problem in its infant stage.

At the time it seemed like a good idea to get an oilpan heater to make those really cold mornings (below 15°) starts easier. This heater did aleviate the lumpy starting.

Cherokee Subwoofer Enclosure

Ever since high school I have used a dual 12" sub box for my car stereo. When I aquired my Cherokee, I simply put my original box in the back. But to utilize the ability to move large objects or large amounts of stuff in the Jeep, I would have to remove the subwoofer. This got real annoying real fast. I also had my car broken into during the summer of 2003; I guess they were looking for a nice system to steal, but luckily my subs were out of the car because I was helping my friend move at the time.

The solution was to build a box into the side of the car. I got a single 10" subwoofer with a very shallow mounting depth (3 inches). This way I could make a box that was camouflaged just like another body panel of the car and the geniuses that break into my car again won't notice there is a subwoofer there.

Jeep Cherokee

I currently drive a 1986 Jeep Cherokee. It's kind of rare because it the 2.5 liter 4 cylinder engine. I've only seen 1 other Jeep with that engine in person, but I've heard of a few on the internet. I'm hoping this car lasts for a long time; it's very fun to drive, comfortable and it was cheap. For a few years I didn't drive it to work everyday, which saved some miles, but now that I live about 8 miles away from work, it's a daily driver.

I consider this car a project because it is very old and going to need attention to ensure it continues to run.