Wont drive forward but reverses fine...

S

shea14

New member
Recently bought a 1990 4runner 4x4 auto, and it's been running really well for the last few weeks. We've only put a total of maybe 25 miles on it, haven't even driven it at highway speeds. I've had all of the fluids (including the trans and differentials) done.

Yesterday, it started locking up in drive. It engages the gear, but doesn't roll forward automatically, it feels like the brakes are locked on. If you push down on the gas it will start to move after a lot of tension. We tried it again tonight, pushed it past the tension point and it moved a foot then made this really awesome sound that sounded like the gears slipping, then it came to an immediate halt. Somehow though, the truck can be driven perfectly in reverse without a hint of an issue...... The responses I've seen all say that somehow low transmission fluid can cause it to move in reverse but not drive forward so I'll be checking in the morning.... If it's not that.. any ideas?
 
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It ran fine before the fluid was changed?

Start with checking the level. And from how your describing it, it sounds like damage has already been done.
 
Agreed the damage might have already been done. Once those clutch packs get hot its game over. It might go in reverse because the gearing for reverse is so high it doesn't take as much force to move it in reverse but that's just my .02.

Did you do a flush or just a tranny fluid change?
 
The fluids were changed when I bought it about a month ago, all of the driving we've done has been after that. Fully flushed and refilled, and from what I can see there are no leaks.

My real point of confusion is the fact that it drove perfectly fine last weekend, it's been sitting still for the last 5 days and now out of nowhere it wont drive. What would cause a truck that drove perfectly and hasn't moved in a week to sustain that kind of damage?
 
Ive heard a lot of horror stories of people doing flushes on high mileage vehicles that have never had a flush before.

The reasoning is all the metal shavings and gunk inside the transmission is stirred up. So now all that stuff is getting into parts causing damage.
 
Diverse4runner said:
Ive heard a lot of horror stories of people doing flushes on high mileage vehicles that have never had a flush before.

The reasoning is all the metal shavings and gunk inside the transmission is stirred up. So now all that stuff is getting into parts causing damage.
Click to expand...

Agreed, they say its best to just top off the fluid rather than shock the tranny by draining it
 
Damnit. Well. I'll pull it apart this weekend and post my findings... hopefully save some other poor shmuck from destroying their tranny.
 
Yea I just drain and fill mine. A flush is when they suck out all the old fluid while forcing new fluid in.

Good luck I feel your pain my transmission went out at 205k started losing gears. It cost me 1500 for a rebuild and I bought the truck for 1500 30k miles ago :-(
 
Alright, good and bad news kind of? The old girl DOES drive forward, but seems to shudder at a specific point, the rear wheels lock up for a second, like someone slams the breaks, then they let go and continue moving forward... happens every 2-3 feet. It sounds like the rear differential slips and then catches again, there's actually a quick 'bang, bang, bang' noise and then it's fine, until it happens again in 3 feet.

Still reverses absolutely fine. The issue seems to be happening at the rear diff..

Any ideas or guesses???
 
shea14 said:
Alright, good and bad news kind of? The old girl DOES drive forward, but seems to shudder at a specific point, the rear wheels lock up for a second, like someone slams the breaks, then they let go and continue moving forward... happens every 2-3 feet. It sounds like the rear differential slips and then catches again, there's actually a quick 'bang, bang, bang' noise and then it's fine, until it happens again in 3 feet.

Still reverses absolutely fine. The issue seems to be happening at the rear diff..

Any ideas or guesses???
Click to expand...

i agree with you on the diff. gonna have to pull apart the axle to pull it out and check it. maybe the roll pin came out of the carrier or spider gears are messed up. only way to know is to get in there. good luck.
 
As others have pointed out, check the level first. I find the trans in our 1990 is pretty sensitive to what fluid I use, and how much is in there. The level and fluid type need to be spot on.
Having said that, we just bought a lower mile(65k), old bmw(1995) that has an auto trans. It took two full services(2 trans kits, 13 qts M1 syn ATF) with M1 synthetic ATF to get the gearbox "right". You might have brought up some sludge in the trans which needs removal/clean up. I've run the pricier standard Valvoline ATF in our 4runner which it seems to like? If the M1 was not so expensive I'd put it in our Toyota, amazing stuff.
regards
 
Any update? My 3.0 Trans does the same thing, but I have absolutely no forward(drive gears) only park and reverse.

Have another Trans/transfer case in garage but would rather not swap Em if I don't have to as all I know is the truck myself and iroke pulled the trans from was"driven to the spot it was in" so condition is essentially unknown.....fluid was red and didn't smell burnt when I drained it before transport over a year ago, never refilled it (didn't see a need to as it's just in the garage)
 
Most likely the forward drum clutches are crispy or the valve body is gummed up. Movement in one direction and not the other usually means a bad clutch pack. I think that transmission as 4 packs in total or maybe 4 packs and a band. I cant remember.
 
While researching the problem further, I ran across a ton of threads about people's rear drum breaks locking up in cold weather, having to put it in reverse to unlock them and then driving fine. While it's been in the high 80's in SoCal, I tore apart the drums just in case. The rear passenger brake was caked in oil and fragments of what looks like a blown apart washer. Cleaned it out, put it back together, drives perfectly.

Sorry all, not much help, but super happy I didn't have to spend a dime to get it running smoothly again.
 
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