Montana changing to higher gear.. jerks hard forward

[abellana]

My montana 2000 is sometimes jerking hard forward, usually on speeds where your changing from lower gears to higher gear. This is usually accompanied by strange sounds every time the engine is revved up.

Please help.

[GTP Dad]

Check the fluid. If the level is not proper it can cause this. Also, have you changed fluid and filter lately? If not now would be a good time and install a new one and put in a can of sea foam or other high quality transmission additive. Should free everything up and may cure the problem.

[Joust]

i have this same problem. A FULL tranny flush and new fluid did nothing to help. Basically, after it warms up (30km) it starts this hrad shifting.

[GTP Dad]

Sounds like you may have a problem with the shift solenoids. They are electronically controlled and either have probably gone bad although the PCM may also have something to do with it. Try disconnecting the power to the van for about 30 minutes. It will reset the PCM. If the problem is in the transmission nothing will change if it is the PCM then the shifts may change back to normal.

[Joust]

i heard its the solonoids.
i'll give that a try cause its free
if it is the solonoids, what recourse do i have? replace them?

[abellana]

As advised, I've added some fluid and additive, its been working since then.. my mechanic advised against too much fluid though as it may leak..

Thanks.

[GTP Dad]

If the solenoids are bad the only recourse is to replace them with new ones. (fairly expensive) Sometimes the valves that are controlled by the solenoids get gummed up and the use of an additive will clean them to the point where they work properly. A fluid and filter change along with the additive won't hurt either.

[MontanaMan328]

I've also had an OCCASSIONAL problem with 'jerking' during shifts. What's different for me is, if it's going to happen, it happens right from the start. It doesn't take a warm up. It will continue throughout the entire trip. In every case, after parking, waiting, then restarting, it's fine again. Smooth as a baby's butt.

Ideas?

Thanx!

[GTP Dad]

Your problem sounds more like an issue with the PCM vs. an internal transmission problem. Try removing the battery terminal to reset the PCM back to factory settings and see what happens. Also a fluid and filter change is a good idea if you have not done one lately although it probably won't matter in your case unless it has been a long time since it was done.

[lastroman]

I have 2000 Montana, and had same problem. If you are gettig this problem when restart engine after warm up. Although it is not sure this gear shifting was the root cause, I had rebuild last summer cost $3300. It didn't shift to 4th level eventually and I saw one gear element was badly demaged when mechanic opened it.
I'll never buy GM car any more. The design itself looked not reliable.
Anyway the point is I'm really suggest you do something.
And worse thing to me is it happened again to me... what do I have to do. I'm not going to spend another 3000 bucks... Thank you.

[cdru]

You were ripped off at $3300. A rebuilt tranny is around a grand. Installation is well under 8 hours. Even at dealer rates, thats under 2000. I reputable transmission shop should be able to do it for around $1500 if you shop around.

[MontanaMan328]

Originally Posted by GTP Dad

Your problem sounds more like an issue with the PCM vs. an internal transmission problem. Try removing the battery terminal to reset the PCM back to factory settings and see what happens. Also a fluid and filter change is a good idea if you have not done one lately although it probably won't matter in your case unless it has been a long time since it was done.

I am assuming that you were addressing my problem. Will disconnecting the battery terminal make my radio unuseable? I bought this van used & do not have the unlock code that I've heard is needed.

Thanks!

[GTP Dad]

It is possible that the radio lock may come on causing it not to work. I would call the dealer and see if they can give you the procedure to prevent it from locking on you so that the battery can be disconnected. If you can find the pcm you can do the same thing by disconnecting the wires from it rather than disconnecting the battery.
Stupid security systems anyway!!!