Auto trans doesn't engage lower gear

[CLE]

Hey,

I searched the forums for a similar thread but couldn't find one.

My transmission (1992 VP auto) seems to be a bit "weird".

What I mean by this is when I'm going down a hill (it doesn't have to be downhill) and I physically move the shifter into say second gear, the revs do not rise. It doesn't engage the lower gear. This is with NO THROTTLE applied. The revs just stay low like before. Same with 1st gear. This seems to be at any speed. Only when my foot is on the throttle will it start revving normally.

When I put my foot on the throttle, second gear engages. When I take my foot off again, it goes back to probably 4th gear and the revs are very low.

Why is this so? I thought that it should change down regardless of throttle position.

The reason I ask is I've been using my brakes a bit too much and my mechanic asked if I change it down to a lower gear on long hills to give the brakes a bit of a rest.

Any idea? I reckon it has been like this since I bought the car and have never thought anything of it.

I hope my trans isn't stuffed.


Thanks for your help

[mischa]

I use my auto tranny like that too not good for it i tell you haha. But im getting it out soon enough so im not worryed about it...

But think about this way, whats more expensive? new brakes? new gearbox?

[CLE]

I use my auto tranny like that too not good for it i tell you haha. But im getting it out soon enough so im not worryed about it...

But think about this way, whats more expensive? new brakes? new gearbox?

So when you select a lower gear, it actually raises the revs? This is when going down a hill with no throttle.

[FATMAT]

Sounds a bit like a snapped gear band.

[Cheap6]

The trans should hold the gear selected manually with the shifter or lower i.e. "D" = all 4 gears, "3" = 1,2 or 3, "2" = 1 or 2, "1" = 1. It sounds like a line pressure or valve body problem to me. (The valves determine where hydrualic pressure is directed to and hence which gear is engaged). If it was a band (or clutch) I would expect that it would also not pick up one or more gears during normal driving. Assuming that is not the case:

The easiest thing to check first is the throttle valve cable adjustment. With the engine off, looking at the throttle body and cables, push the metal tab in the plastic housing holding the cable closest to the front of the car. The cable should spring back on the ratchet. Open the throttle by hand 'til it hits the WOT stop and the sheath on the TV cable should move out to the correct position (and stay there).

You can check that the cable isn't broken by gently pulling on the TV cable (wire part). It should feel like it is attached to a light spring (it is). Normally a broken cable would cause a poor shift under normal driving though.

A look at the auto. oil might help too. If the trans has been slipping, the oil will be dark rather than red and there will be bits of sediment (clutch or brake material) on the dipstick. Sometimes that ends up in the valve body and causes the valves to stick. Wear in the valve body can also cause the valves to stick.

One other possibility is the seals in the valve body or oil pump leaking - if the 'O' ring on the speed sensor is or has been allowing an external oil leak (because it's hardened up with age) it's a good chance the internal seals and 'o' rings are similar.

[CLE]

The trans should hold the gear selected manually with the shifter or lower i.e. "D" = all 4 gears, "3" = 1,2 or 3, "2" = 1 or 2, "1" = 1. It sounds like a line pressure or valve body problem to me. (The valves determine where hydrualic pressure is directed to and hence which gear is engaged). If it was a band (or clutch) I would expect that it would also not pick up one or more gears during normal driving. Assuming that is not the case:

The easiest thing to check first is the throttle valve cable adjustment. With the engine off, looking at the throttle body and cables, push the metal tab in the plastic housing holding the cable closest to the front of the car. The cable should spring back on the ratchet. Open the throttle by hand 'til it hits the WOT stop and the sheath on the TV cable should move out to the correct position (and stay there).

You can check that the cable isn't broken by gently pulling on the TV cable (wire part). It should feel like it is attached to a light spring (it is). Normally a broken cable would cause a poor shift under normal driving though.

A look at the auto. oil might help too. If the trans has been slipping, the oil will be dark rather than red and there will be bits of sediment (clutch or brake material) on the dipstick. Sometimes that ends up in the valve body and causes the valves to stick. Wear in the valve body can also cause the valves to stick.

One other possibility is the seals in the valve body or oil pump leaking - if the 'O' ring on the speed sensor is or has been allowing an external oil leak (because it's hardened up with age) it's a good chance the internal seals and 'o' rings are similar.

Hey, thanks for your reply.

Oil isn't a problem. I changed it a month or two back and it seems okay. Right colour and level.

I'll take a look at what you suggested.

Thanks for your help!

[mischa]

So when you select a lower gear, it actually raises the revs? This is when going down a hill with no throttle.

yeah, thats what its sposed to do normaly.

[Cursed CX8]

id say that it is dropping the gear, but the torque converter is not locking up. when you apply the accelerator (noise pedal) does the gear box drop into gear with a jolt, or do the revs just rise to meet the speed? If the revs just rise up its because the torque convertor is locking. If it clunks into gear then its a gear box issue.
It wont be the bands, because the trans would not shift into 4 gears whilst in drive.

[CLE]

id say that it is dropping the gear, but the torque converter is not locking up. when you apply the accelerator (noise pedal) does the gear box drop into gear with a jolt, or do the revs just rise to meet the speed? If the revs just rise up its because the torque convertor is locking. If it clunks into gear then its a gear box issue.
It wont be the bands, because the trans would not shift into 4 gears whilst in drive.

Yeah it goes into gear if you put your foot on the accelerator, but as soon as you take it off, the revs drop right down. Goes for any gear.

I could be doing 60k, put it into first gear with no throlle, when when I use the throttle the revs rise appropriately, but drop again with no throttle applied.

Is my tranny totally stuffed? Still drives okay otherwise.

[Cursed CX8]

id say its the torque converter not locking, take it to an auto joint, let the tech drive it and see what he says

[Cheap6]

If it's behaving as described, it's definitely not working correctly. As to whether it's truly stuffed, that depends on what is actually wrong with it.

The torque converter only applies in 3 or 4, and then only at constant engine loads, so it doesn't sound like that is the problem. It can be hard to diagnose something using text, so I agree, consulting a trans. tech. may be the best way to go. A quote (or guess) is usually free in any case.

One other simple check I didn't mention is that the oil level has to be checked with the trans. hot - the level will read lower hot than it will cold.