Friday, July 23, 2010

Free VIN check

Auto check is basically free if we use the following website and put the VIN after "&vin=" .


Wednesday, July 21, 2010

Change front and rear gear oil and transfer case fluid of Jeep GC 2001

This is actually a big lesson for me:

I used a fluid transfer pump to  drain and refill the front and rear pumpkin. There was no trouble.

But replacing the ATF+4 in the transfer case which was the easiest job in my memory turned out to be a headache for me: I damaged the magnetic drain plug: I thought I could use the 3/8" hex socket to take it down which was what I did. But this time, I could not do that any more since the right socket is the 10mm or 7/16" hex socket. The washer head of the drain plug was turned by a smaller hex bit to be rounded.

Asked around and found some possible solutions to extract the rounded-off plug:

1. Use a cold-chisel and hammer it into the female drain plug and make a notch in it. Then use visegrips to turn the chisel and take out the damaged drain plug;

2. Welder a regular square male bolt into the female plug. Use wrenches to unbolts it;

3. Use a special tool called Pipe Nipple Extractors. They are available at Princess Auto in Canada and Harbor Freight Tools in the US.

Too bad my Jeep is sleeping at the parking lot and I have to buy tools taking Bus.

Update: I had to spend 30 bucks to ask a garage to weld a regular male bolt into the female plug. I replaced the damaged bolts.


Monday, July 12, 2010

A possible reason for Tranny slipping

I once came to the symptom that my Jeep couldn't move when I hit the gas.  I replaced the governor pressure sensor and solenoid because I had sluggish tranny shifts and P1756 code. After the governor pressure sensor/solenoid replacement, the tranny runs like new.  So I only need to keep an eye on it.

If tranny slipping will repeat, I might need to replace the  TPS (throttle position sensor). The procedure to diagnose a TPS is explained at the website The following is the diagram for TPS removal and installation.


Sunday, July 11, 2010

Jeep GC creeps in neutral

My Jeep GC 2001 creeps in neutral. However, it won't accelerate when hitting the gas pedal, which means that the clutch is indeed disengaged. This seems not normal but some guys found this phenomenon and explained that the tranny gears would still rotate by the fluid turbulence which is propelled by the engine output shaft.

Moreover, it is quite interesting that one Jeep guy was very much proud of the ability of Jeep GC that it could "idle in neutral and crawl up an incline at 10,000 feet in the mountains", which is exactly the phenomenon I am worried about!


Thursday, July 08, 2010

Flush the cooling system of Jeep Grand Cherokee 2001

There are three parts for cooling system of a typical vehicle: radiator, reservoir and engine block. There is a plastic drain plug underneath the radiator which can drain the coolant in the radiator and reservoir.

However, it is not an easy job to drain the coolant in the engine block of Jeep grand Cherokee 2001, since the drain plug located under the intake manifold is a female pipe plug. We need a 5/16" male pipe plug socket to take  it  down. Despite the possibility that the plug would be rusted and get stuck in the engine block, the 5/16" pipe plug socket is very rare in the Canadian market. I searched around the city of London in Canadian Tire, Part Source, Rona, NAPA, Home Depot and Federated Tools, without any luck.

The original coolant in my Jeep is the conventional ethylene glycol based green coolant. I cannot change it to the more advanced orange long life HOAT coolant because mixing green coolant with the orange type would produce some sediments in the cooling system which are highly harmful to the components of the cooling. system.

An informative article by James B. Wills, Jr.  reads
An alternative to tradition green antifreeze is a product currently used by many engine manufacturers. "Orange" antifreeze is a long life or extended life type of antifreeze used to increase the useful life of engine coolant. It is ethylene glycol base as is the green antifreeze. The difference between the two colors is that orange antifreeze contains a different type of corrosion inhibitor that has a much longer service life than silicates, phosphates and borates. Orange antifreeze contains organic acids that protect engine parts from corrosion. Silicate (green) type antifreeze does not mix with orange type antifreeze. Never mix the two colors in a cooling system. The organic acids in orange types will cause precipitation of silicates in the green type and corrosion protection is greatly reduced.
Now that it was difficult to drain the green coolant  in the engine block, I had to stick with the green coolant and just replace the old coolant in the radiator several times. The following is what I did today:

1. Bought two jugs of concentrated regular coolant from Jeep dealership. 2X 3.78 Liter, 17.7 CAD per jug;

2. Bought two jugs of distilled and ozonated water. 2 X 4 Liter. 1.67 CAD per jug. Open the lids and dispose them in sunshine for two hours letting the ozone out;

3. Use a 2 feet gardening hose as an extension to the original drainage hose at  the drain plug and put one end of the extension hose into a bucket with measure scale;

4. Open the drain plug located at the left corner of the radiator facing the rear of the vehicle (NOTE: The service manual said it was at the right corner of the radiator!); That is, it is to the passenger' side. Then twist the valve counter clock-wisely 270 degree.

5.  The total amount of the old coolant drained from the radiator and the reservoir is 7.5 liters, which is 60% of the coolant in the cooling system (12.3 liters).

6. Put a half jug of the concentrated coolant into the radiator and then a half jug of the distilled water;

7. Mix the remaining half jugs of water and concentrated coolant together. Pour the mixed coolant into the radiator and the reservoir jug.

8. Let the car run for at least 10 minutes and bring the system into working temperature. Repeat 1--7 after the system cools down.

The following are simple arithmetics: After the first round (step 1 -- 7),   60% old coolant was replaced; After the second round, 84% was replaced; 


Monday, July 05, 2010

Replacing Brake Rotors and Pads of Jeep Grand Cherokee 2001

Due to the twin-piston design of the front calipers of 1999-2002 Jeep Grand Cherokee, the pads are easy to contact the rotors unevenly and the uneven wear can cause  excessive rotor warp-age. The brand name of the caliper for 1999 - May 10, 2002 Jeep WJ is Teves (black color with open-sided bracket). For WJ after May 11, 2002, the caliper has been replaced by another type with brand name Akebono (silver color "fully closed" style).

My Jeep unfortunately falls into the time interval  1999 - May 10, 2002 and has  Teves calipers.  Recently I felt much pulsation when I hit the brake, which means that replacing the brake pads and rotors becomes necessary. One could choose to replace the calipers as well. But for me, it will cost too much for a 9 years old car. So I would like just replace the pads and rotors and hope I could use three more years.

I am not going to detail the steps on how to replace the rotors and pads since no special techniques are required for Jeep. All the steps are standard. However, I would like to record the tools and toque specifications in the following because it took me much time to find the correct tools to finish the service as the service manual did not give such specifications:

Tools and toque specifications
1. To remove the caliper mounting bolts, we need a Torx T45 bit;

2. To remove the bolts of the C bracket, we need a 18mm socket;

3. To service the brakes by oneself, it is highly necessary to have a heavy duty torque wrench which has a long handle; It will be very helpful to remove the 18 mm bolts of the C bracket;

4. Use 13mm socket to remove the lug nuts.

5. The torque of the mounting bolts is 15 N . M  (about 133 in lbs) 
    The torque of the bolts of the C Bracket is 17.5 N. M. (155 inch lbs)
    The recommended torque for lug nut is 115 ft lbs.

The following are some tips I learned in the project: 

a. The brake disc would get stuck with the wheel hub. One normally needs to hammer it off. To save some effort to hammer the disc, we could spray some WD-40. If this still can not work, we can use the C-clamp in this way: put a wrench with a hole in the handle on  one of the lug nut bolts, lock it with a lug nut, the wrench will cover the  center of the wheel hub. Then set one foot of the C-clamp on the wrench head (cover the wrench head with some wooden materials), the other foot on the brake disc. Rotating the handle of the C-clamp will produce some force sending the disc off the hub. If the force from the C-clamp does not take off the disc,  then hammer the back of the disc at the same time. Some-times knocking around would help unlock the rust.

b.  When we install the caliper, the disc might sway off the surface of the wheel hub. This could cause some trouble to put the caliper in place.  One can use the wrench and lug nut once more: overlap two wrenches with holes in one end  and let them sit in the lug bolts, lock them with a lug nut. In this way, the brake disc won't sway anymore.