'97 4WD acting up, and timing chain question

[MikeDog123]

Yesterday I noticed that the 4WD on my '97 Explorer started engaging for no apparent reason. Also, the 4WD and 4WD Low lights flashed together. Later in the day, it seemed to stop. What could be causing the hubs/transfer case to engage like that?

Also, I got my Explorer (4.0 OHV) at 70,000 miles, and it has 105,000 now. I don't know if the timing chain has ever been replaced. When should I start worrying about it? I'm ignorant - is this an engine that is damaged when the timing chain breaks while running?

Thanks,
Mike

 

[Bronco638]

The flashing dash lights are a code the will provide a clue to the problem. Try to count the flashes the next time it happens. A dealer will be able to read the codes and tell you what they mean. If you borrow a code reader (AutoZone), you can read the codes yourself. Then post them here and someone will interprete them for you. Could be lots of things.

As for the timing chain, I think that a broken chain in an OHV engine will simply cause the engine to stop running (no internal damage). A SOHC engine will sustain damage. Since this is a chain (not a belt) it doesn't have to be changed as often (105K should be OK).

 

[TPLYNCH]

Probably a problem with the speed sensors on the T/Fcase. Faulty readings will cause the auto 4x4 to kick in, and/or cause the flashing codes. 6 flashes, repeated, is an indicator of speed sensor error.

Shouldn't have to replace the chain on the OHV. Should last the life of the engine.

 

[MikeDog123]

Someone suggested to me that the 4x4 kicking in could be the result of different tire pressures in the tires, making the computer think the wheels were slipping. I have equalized the pressure, and the problem has stopped - don't know if it is a coincidence or not.

Where are the sensors located? Are they at the wheels, or in the transfer case?

 

[Bronco638]

On my '96, one sensor is in the t-case, just below the rear driveshaft. It has three or four wires running into it and is held in place by a small bolt.

 

[TPLYNCH]

Mismatched tire sizes (either by having one tire low on air,using new and used tires at same time, or 2 different sized tires) will cause the auto 4x4 to kick in. There are 2 sensors, one on the front of the t/f case and one on the back.

 

[MikeDog123]

The tire pressures are equal - The problem went away for a few days, but now it is back and in 4wd all the time. After a few miles, the lights flash 6 times and the 4wd is disabled. Is there something I can do with the speed sensors before I spend money at the shop? Are the speed sensors only in/by the transfer case, or does the system use sensors at each wheel too?