Front End Seized in 4wd - Drives Fine in 2wd

toyota
tacoma

#1

I was driving to work today in my 1998 Toyota Tacoma in 4WD on snow covered roads. I had driven for a few miles without a problem when, without any prior warning (that I noticed), the pickup came to a screeching halt. The stopping force clearly came from the front end. I got out of the car and noticed a little bit of a weird smell, but didn’t see anything out of place. I got back in and started it back up (manual transmission so the abrupt stop killed the engine) without problem. I still had the car in 4WD not yet really knowing what had caused the problem and tried to drive. I got nowhere. I took it out of 4WD and again would not budge forward and it still indicated it was in 4WD by the light on the dash. I let off the brake with the clutch in and rolled backward and it immediately went out of 4WD. I was able to drive fine in 2WD without any weird indications. I pulled off on the next suitable street and tried again. Once in 4WD the car would not go forward or backward. I again got out of the car noticing the smell, but this time, much worse. I looked underneath the pickup and noticed nothing appeared out of place with no leaks. The smell was gone almost immediately. I put it back in two wheel drive and drove it back to park it near my house.

I have not had a chance to check the fluid levels yet. The only other similar symptoms I have found on the internet so far are discussing a pinion bearing seizing / breaking off teeth.

The pickup has 230,000 miles and I recently got it from a guy who was the second owner and did a lot of work on it himself. He recently replaced the U-joints, ball joints, inner tie rod, rack bushings and lower strut mounts. We do not live in an area where 4WD would have been required on a regular basis. I use it for a commuter (5 miles city driving) on days when my wife also needs a car and for work around the house.

Any idea what would cause the problem or good ways to troubleshoot to narrow it down? Is it safe to continue to drive it in 2WD or is that going to cause greater problems?


#2

How fast were you going when it happened originally? Could have burnt up the transfer case by driving too fast/long in 4wd or by using it on a road that was too dry.


#3

I suspect a locked-up front diff. Rolling in reverse probably allowed the gears in the transfer csse to unbind and release. Either way, don’t keep driving it around until you know what broke and what the fluid levels are unless you want to make it worse.


#4

Guys, correct me if I am wrong, but 4x4’s aren’t supposed to be driven in 4X4 mode. That’s only to extract yourself from tough spots.


#5

I was driving about 15-20 MPH in 4HI when the sudden stop happened. The roads were not dry at all, they were covered in snow. We got about 8 inches of snow and the plows had only hit the freeways at this time. I grew up in an area that sees snow like this on a regular basis and have a very solid understanding of the proper utilization of 4WD, I was not doing anything wrong in that department. Any specific troubleshooting techniques on the issue to determine if it is a locked up front differential or any other causes? Thanks.


#6

U tried to move forward in 4wd and could not. Did u try to move backwards in 4wd? U said u could only move in 2wd so it’s unclear, to me


#7

The car would not move in forward or reverse while engaged in gear and in 4WD.


#8

You were using the 4 wheel mode exactly like it should be used. No issues there.

I’ll second the front diff locked up and the smell was probably the roasting of your clutch disc slipping.

check this link out-


#9

TwinTurbo - that is the only other similar article I have found and the symptoms are identical. Does this require a complete replacement of the differential or just the pinion bearing? I have a Chilton’s manual describing how to do the job and access to a shop with a lift and full complement of mechanics tools, is this is job that a mechanically inclined novice can tackle? Any other good resources for direction on a potential job like this or troubleshooting tips to confirm that is what the problem actually is?

If this is indeed the problem, will it be alright to continue to drive in 2WD and just not use it when 4WD is necessary? I purchased this pickup just to have a secondary vehicle when necessary and haul stuff when I need it. If I can get a good amount of miles on it without having to fix the problem (if it is going to be a costly fix), that would be preferable.


#10

Hope my comment earlier wasn’t offensive @gabeha. I ask because there’s a tremendous number of people that DON’T know how to use 4wd. Glad you’re not one of them.

I can’t offer any advice on specific troubleshooting or repair for the front differential, but that sure does sound like the problem. If it is, then you should be able to drive in 2wd indefinitely without repairing it. I would check the gear oil though just in case it was somehow contaminated in both the transmission, transfer case, and the rear differential. Something caused the front to fail, and that could have potentially been low/no gear oil.


#11

I had someone look at it today that was able to confirm the front differential is frozen. Now I am just deciding if I want to crack it open and spend the money to fix it or if it will just be a 2WD pickup from here on. At 230,000 miles, the truck probably has a limited life ahead.

I will update the forum if I do open it up to let you know exactly what failed to hopefully help someone else in the future.

If anyone has any good resources for the technical knowledge to help me out if I decide to do this myself, please share it.


#12

@gabeha

If you just drive it in 2wd mode from here on out, you might be surprised how much life is left in the truck . . .

Toyota makes tough little trucks


#13

I wouldn’t be able to NOT open it up just to see what happened. If it’s full of shrapnel that’s one thing. If I decided to run indefinitely in 2wd I would probably remove the two front axles. Again not positive about Toyota setup but I wouldn’t want anything turning in that housing. If the axles are disconnected from the hubs by some external means OK.

After confirming it’s a hopeless meltdown, I might just search for a complete front axle setup in the junkyards. There’s bound to be a selection, that’s a popular truck. You might get off reasonably cheap compared to repair and easier to do wholesale swap.


#14

I suspect it is worth fixing, if the rest of the truck is solid. I have a friend that just retired a 98 Tacoma a couple years ago with 465000 miles.


#15

If the front diff is toast, you could always remove the front driveshaft . . .


#16

Remove the front drive shaft and figure out some way to make sure the front hubs can not lock.


#17

@CapriRacer , I’ve driven my 4x4 truck in 4WD for a hundred mile trip sometimes without problem. Dirt roads. In some cases no roads. You aren’t supposed to drive them on paved roads in 4WD, maybe that is what you meant, but on dirt road or hard packed snow road it is ok to drive for long distances in 4WD. It would be common sense to not drive super fast in 4WD of course. I rarely would drive faster than 45 mph in 4WD, if for the only reason it was impossible to go much faster due to the road conditions. Mostly it was below 25 mph.

OP, it could be the differential as mentioned above. Check the differential fluid is something to do. If you have manual locking hubs, it could be something to do with those too. The hub assy’s on each side would have to be disassembled for a look-see. On my truck at least, if the lube maintenance for the hubs is behind schedule, that can do strange things.