Truck Problem, any ideas?

S

Shann

Joined
Sep 2, 2004
Messages
5,250
I've got a 2002 Ford Ranger FX4. It is a 4 wheel drive manual with a manual transfer case and a Torsen limited slip differential. I have 140,000 miles on it. Two issues have cropped up. One is that it sometimes pops out of 4WD, particularly when cold. This can be very dangerous. The dealer said a cog is worn out but that Ford doesn't make a replacement part. I either have to replace the transfer case or find a used one but the labor is high. That probably can't be helped.

The second problem is a mystery. While driving on slippery road, either in 2 or 4 wheel drive, the truck will buck. I first thought it was the engine, you know it felt like it wasn't getting gas or something and would cut out. However, it is coming from the rear end. The dealer has not found anything wrong with the rear end. I suspect its with the limited slip but it really is annoying. Has anyone had this problem and any ideas?
 
Hi Shann,
Have you checked the gear oil level in the transfer? Probably won't help much (or at all) but maybe the level is too low.
As far as the bucking, is it only on a slick road?
 
A couple questions...
1. Does this truck have a limited slip rear differential (aka "posi" or "Trac-Lok")?
2. Does it buck when moving straight or when moving through a turn, or both?
3. Why do you say it is coming from the rear end?
 
Yup. It has a Torsen limited slip rear differential. It bucks while moving in a straight line. It feels as if its coming from the rear end rather than the engine. I have never had it happen except in slippery conditions not related to rain, etc. and do not believe it to be engine related. Whether its the rear axle or just something in the drivettrain I really can't tell.
 
If you have a Limited slip rear accel, you might want to change the oil in there.
The oil has some kind of stuff in it to limit slipp, and this wears out after a while..
 
If you are sure its a torsen type and not a trac-lok (that is to say clutch) type LSD then its unlikely the cause (though I suppose anything is possible), if its a clutch type LSD then you may be in need of some extra friction modifier.

How many miles are on the truck and what speeds does it do this? A lot of 90's era Ford transmissions used a torque converter clutch to achieve lock up in 3rd and 4th gears with some slip allowed in 3rd gear. This caused them to be very sensitive to "old" fluid, in essence the various friction modifiers in the MERCON (or MERCON-V) would burn off eventually and result in shuddering and un-smooth engagement. Another common problem was very similar in feel. During the 2-3 and 3-4 shift the PCM would decrease fuel or timing and if you have any type of slight misfire or weak ignition wire/coil/plug you'd feel a very notable vibration much like going over a rumble strip from the misfire.

If it just feels like chattering going through a turn its probably the rear end's LSD needs some more FM. If it feels like bucking and chattering under heavy acceleration on slick surfaces where you'd expect wheel spin you may be suffering from axle hop. Otherwise consider the transmission fluid or a misfire condition (which may or may not pop a code). If those don't solve it then I suppose your beyond the common problems I'm aware of.
 
now can you find a good person that works on ford around you? I have one and he seams to know the bad and good about all the cars and trucks. I have a dodge and I keep going through front breaks and yet I have not touch the back breaks and he told me why that was. I hope you can find some one like that. if you cand can you just trade it in for a newer one that doesent have these problems? my dodge has about 179000 miles on it and the reason I dont trade it in is because it doesent break down all of the time and if you do trade your in then I wish you find one like mine.
 
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