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Toyota Corolla 2
9 Posts
Discussion Starter · #1 ·
I have a 1999 Toyota Hilux 4x4 (LN166) in which i have just installed a Toyota 3.0D (5L) engine. Previously the car had the 2.8D (3L) engine. I did not change the gearbox. I have driven the vehicle for almost 20 000km without a major problem. I use the vehicle quite often on dirt/muddy roads, though most of the time i use the vehicle in town.
Last weekend, while I was out in the bush, i suddenly could not engage gear 5 and reverse. I stopped and looked under the car to see if there is anything i could do. I saw that 2 of the 6 bolts that mate the gearbox to the engine were missing, and one was loose. Despite this, gears 1-4 were engaging well. I found some bolts and screwed them in as a rudimentary measure just to get me to my destination about 80km away. I tried to tighten the 3rd bolt - it would screw in well, but it would not tighten.

I have spoken to my mechanic who was surprised by this. He indicated though, that it can happen, especially on older cars - gearbox bolts can work themselves loose due to metal fatigue and vibrations. He also indicated that one of the ways to rectify this is to tighten the bolts with nuts. He also visually examined the 3rd bolt that wouldnt tighten and saw that the threads were still very good indicating that maybe the threads on the gearbox or engine are the ones that are worn.
He also removed the gear sticks and cover to test the selectors and they appeared to be ok indicating that the gearbox has an internal problem.

I thus have 2 questions:
1. Is it really true that bolts can work themselves loose to the point of falling off?
2. What would cause the gearbox to suddenly fail to engage gear 5 and reverse? (we havent opened the gearbox yet - am a little short of cash...:sosad:)

Any help that i can will be greatly appreciated.


Bring On The MUD!!!!!
'83 Pickup SR5
2,334 Posts
for starters, yes, bolts and nuts can easily come loose due to vibration. i have made it a habit to use lock-tight on any bolt or nut that is going to be under a high amount of stress.

as for the gear box not shifting into 5th or reverse..... my first guess would be that somehow the shifter is not lining up with the gears inside. other than than im really not sure. the only thing i could suggest is checking either the clutch and flywheel or making sure your oil is still good. you might also want to see if there are any metal shavings in the gear box oil...


Mini Truckin Done Right
94' Toyota MiniTruck
13 Posts
I agree, bolts are always coming out, when I replace anything I'm a fan of lock tight it’s cheap and effective. if you do find that the engine or the gear box is in fact striped drill it a bit bigger and tap it and go larger with the bolt size depending on what bolt holes they are you should have more than enough room.

And as for 5th and reverse... Toyota has done a great job with they’re syncros, but I do see time after time they do go out, and when they do the gears start grinding the slightest bit and over time they just do not grip anymore.

It may be cheaper to pick up a used one, but if you do re-build it, it will last longer than the motor.

Also its costly but worth it.... after you replace/rebuild useing syncro mess from GM works great to make the life of your syncros and gears inside the gearbox, its like $12-$14 a quart.
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