Problem with 4sp overdrive on trip

[burner1963]

Hey there! I have a '86 VL Berlina with its SECOND gearbox (first one ditched it with a multitude of gearbox probs...), and during a trip interstate, the 4th gear overdrive just stopped working - no warning, nothing... The button on the gear shift did nothing, and at 100km/h, the revs were up at around 2100. When I arrived at my destination, I checked the transmission fluid - level ok, and colour/smell seemed ok too (when my last gearbox bit it, 4th gear had already become a bunch of shards at the bottom of the transmission casing, and about a month later, the clutch plate(?) was shot, and the trans fluid was BLACK and smelled burnt; luckily, it seems I'm not at that stage again)

Any hints as to what's happened?

Cheers,
Fred

[premium]

Personally I have a Manual. But I know that the Automatics won't go into Overdrive unless the Power button is turned 'OFF' and the engine has reached operating temperature. Is the thermostat working Ok?

[burner1963]

Hey there!

As far as I know, the thermostat is fine. The overdrive was working perfectly for about 500km of the journey, I stopped to get fuel, and then it wasn't working at all when I took off again. Didn't do anything screwy at all, so it's a mystery to me - it didn't make any difference what position the orange button was in; it just wouldn't change to 4th...

[premium]

strange, but I don't know much about Automatics.
That's why I drive a manual!

[harry3]

I dont know whats wrong but you get 4th from the overdrive unit thats behind the auto

[burner1963]

Thanks for your replies, people! Much appreciated!

Gonna show my MASSIVE ignorance here, but do you think it could be heat/pressure related? My understanding is that there's a heat/pressure sensor that kicks in the 4th gear, so if that sensor is malfunctioning... Just a thought...

Cheers, and thanks again!

[Goon]

from what i know and i have an auto is that overdrive kicks in after 80 after i warms up during cold start..

as for the power button, i dont think it takes any effect if the cars going to overheat or the temp gets to high, something like that.

pwr button cant be used over 80 or ur going to do damage...

pwr button also go's into 3rd and not 4th.

[burner1963]

I dont know whats wrong but you get 4th from the overdrive unit thats behind the auto

Thanks, harry3!

Do I take it from your reply that there's an overdrive unit that's sort of separate from the transmission itself? If so, I guess it could be that unit at fault...

Geez, I just don't want to have to try getting a gearbox replaced at this time of the year...

[detox_nath83]

another one could be loose plug under dash near steering column on the trans ECU
If stuffed or unplugged it will not go in to overdrive its will only use 3 gears
power button on T bar could be faulty as in when pressed and power light is off on dash cluster it still may not be off only the light indicator is off..
catching what im throwing???

[jatsvl]

there are two solenoids on the side of the trans 1. torque converter clutch solenoid front 1 closest to the bell housing. 2. overdrive cancel solenoid, if no.2 is disconnected there is no 4th overdrive. get under the car and you will see them with large electrical plugs attached on passenger side of the box.

Goon, you can use the power button at any speed it is suppose to be used when towing so as not damage the trans when the torque converter cluch engages. also out of interest power button on or off 3rd and 4th will reach and maintain the same maximum speed of around 200kms/h however 4th overdrive takes way longer to reach top speed above 170kms/h, and there is no risk of damaging your transmission.

[Goon]

there are two solenoids on the side of the trans 1. torque converter clutch solenoid front 1 closest to the bell housing. 2. overdrive cancel solenoid, if no.2 is disconnected there is no 4th overdrive. get under the car and you will see them with large electrical plugs attached on passenger side of the box.

Goon, you can use the power button at any speed it is suppose to be used when towing so as not damage the trans when the torque converter cluch engages. also out of interest power button on or off 3rd and 4th will reach and maintain the same maximum speed of around 200kms/h however 4th overdrive takes way longer to reach top speed above 170kms/h, and there is no risk of damaging your transmission.

ur revs would be insane its why it has a yellow and red limit on ur rpm gauge, ive read this and been told by an auto electrician who has 4 fken rb30 type cars and 2 rb25 type cars. ill stick by what i know and u do the same

[jatsvl]

towing a trailer or caravan at the speed limit (upto 100Km/h) and having your torque converter clutch (overdrive) activate will most certainly destroy your trans prematurely.

my point being pwr switch can be used at any speed, towing or not.
good thing your mate is an auto elec and not a trans mechanic.

[Goon]

towing a trailer or caravan at the speed limit (upto 100Km/h) and having your torque converter clutch (overdrive) activate will most certainly destroy your trans prematurely.

my point being pwr switch can be used at any speed, towing or not.
good thing your mate is an auto elec and not a trans mechanic.

well if u heard that or u are the trans mech thats good stuff to know, ican put 2 n 2 toghthere and have different sides to talk about

[jatsvl]

of course on several different occasions I had the opportunity to max out my cars top speed both with pwr on and off with the same results making it to the yellow not the red the car still runs to this day with no problems, so it is not what I have heard it is what I have done.

[Goon]

of course on several different occasions I had the opportunity to max out my cars top speed both with pwr on and off with the same results making it to the yellow not the red the car still runs to this day with no problems, so it is not what I have heard it is what I have done.

nice, im try it oneday when i get another vl auto, must be fast and loud.. but dam fast, i love that button! its my standard "seeya!!"