Shifts in a 2000 Montana; please not the whole trans.

[21Rouge]

We live north of Toronto. Our family has owned since new a 2000 Pontiac Montana minivan. It currently has about 104,000 km. In September/04 I took it to the dealership because I noticed, on occasion, i.e. not always, that the auto transmission would have harsh,noticeable shifts and when this was happening one could hear a whine from the engine/transmission during acceleration.

It took me a month or more to bring in the car because not always would the problem occur. And when it did occur it would often stop if I turned the car off and then restarted. Eventually I was able to drive it to the dealership during an episode and get a rep to drive with me. They eventually diagnosed it as a problem with a sticking pressure control solenoid with the sticking due to
sediment build up (I am looking at my September/04 invoice). So almost $700
Canadian later it was fixed.

At the end of March/05 just over 6 months later and 12,000 km more and the same problem reappeared. With a little looking I did find an appropriate TSB  # 00-07-30-002B which I printed and brought into the dealership.

I get a call from the service manager later in the day. Forget the warranty for this one; he says the solenoid is not defective but the codes indicate that it was indeed sticking open. But this time, unlike last time he says, the transmission fluid in the pan shows some metal filings and it is this he says that causes the solenoid to stick.
This time he recommended draining and completely changing the transmission fluid rather than taking the transmission apart at this point for a further diagnosis....so this time about $150 as I recall.  

It is now May and about 3 thousand kilometres later and although the problem has not reoccurred...although it sometimes 'feels' like there might be a relapse...not sure. I am definitely not car savvy so I am trying put together a course of action if/when it does resurface. What could the next steps be re a proper diagnosis and solution. From what I have told you is there some things that might be done prior to jumping to the total dreaded transmission replacement?

[Smainville]

Barrie1, our GM expert will be along to provide you some insight.  Hang in there.

[weebl]

Sounds like the tranny flush has kept it at bay, and you should get some more life out of the tranny, but as Smainville says, Barrie1 will be along shortly as he knows GMs inside and out.

[barrie1]

Boxgrover Welcome to the forum. This tranny should be flushed and a new filter go in about every 80,000klms under most driving conditions. If you live in the country where you travel a lot of dusty dirty roads it will be done more often. They have an outside breather like all 4 spd trannies and it does draw a certain amount of dirt in with it. You may still have a bit of dirt in there as well as metal filings which will cause the odd glitch in the box. The next fluid change will probably get the rest of the dirt out of it. Keep it clean and this tranny should last you for years as they are a very well made product. They are one of the best in the market place to-day. Many other brands have used the GM tranny's under license for many years now and I believe some still do. A hard shift is sometimes very good for this design as it clears the dirt and debris thru the valves very quickly and does less wear. Generally speaking the harder faster shifts are better for the tranny. Just keep the fluid clean and the filter up to date and you should be alright.

[21Rouge]

Yikes you guys. I wasnt expecting such comforting news. We had put vacation plans on hold as I am/was? expecting to need a transmission replacement this summer...no money for both.  

So *whenever* the very harsh shifts and whine return (and they were hard and pronounced and it was very whiney) you would recommend that I again replace the tran fluid and filter, and.... maybe...clean the valve body someone else had suggested?

[barrie1]

Yes as that will extend the life of this tranny. Just like any engine you have to change the fluids before they cause problems. I would plan on a service period of around every 50,000 klms to have this done. I wouldn't touch the valve body unless it is required. If you are towing with it then I would have a tranny cooler installed as it will help you a lot as well.

[21Rouge]

I appreciate the replies Barrie1. But I want to understand my car better. I do want to see the glass as half full but...when they replaced the PCS in September the fluid and filter was replaced as well. 12,000 km later same symptoms arose and again the fluid and filter replaced. It has been almost 3000 km since that time and so far ok. But if the hard/rough shifting occurs again as described in the TSB...say just next week, you would again replace just the filter and fluid? Is there any advantage to getting a synthetic transmission fluid? (And this van does not do any towing)

[barrie1]

The hard shifting quite often is a good sign of condition on this tranny. The faster the shift the less wear and damage occurs when the fluid goes thru the valves. The faster the better for the tranny although it is a harder shift. They can adjust the shift if its too hard fairly easily. You should be good for a while on the fluid. Sounds like your tranny is working fairly well now.

[articsteve]

I think your original problems were from lack of maintenance on the transmission.  Most likely on the first repair the dealer did not remove all the old transmission fluid. Quite often it actually will need two full flushes to really clean it out, but customers rarely want to pay for that so dealers don't do it.  Consequently, 12K later it needed another one.  That is not abnormal.  Next car you get service the tranny at 48K or 2 years.

IMO, when these GM transalxes automatics start hard shifting at the mileage you have where they have never normally done so before, then it is time to dump it. FAST

I would not put synthetic tranny fuild in it at this point.

Have you had the intake manifold gasket replaced yet under warranty?

[21Rouge]

Live and learn. If I knew back in September the problems that would develop from then on I would have sold it. But now I am in a bit of quicksand with this van. New car on the way to replace our 2nd car (not the van); expensive repairs done to the Montana unrelated to the transmission which of course wont be recouped in a sale; and a transmission on the edge...I couldnt sell it privately in good conscience. And yes the intake manifold gasket was replaced during the warranty period. We hope to use the Vibe as much as we can but with 5 in our family and a couple of hockey bags and sticks it wont be easy.

[articsteve]

Live and learn

So do us all.

The thing is that for some reason car owners totally neglect the transmission and manufactures don't make it easy either.

You may never have any further problems with the transmission.  Two years from now get another flush.

[safristi]

It'll be full of it in 2 years....!!!

[barrie1]

Boxgrover the reason I asked if you towed with this vehicle was because you would put on a tranny cooler which does several good things. It increases the amount of fluid in your system and helps keep the tranny running much cooler. There's a lot less stress on the tranny this way. I would not switch this tranny over to synthetic fluid as its not going to do much for you at this late stage of ownership other then cost you a lot more money for very little if any benefit. A tranny cooler can be installed for under $100. at most garages and may help extend the life of the tranny. Just keep driving this vehicle until the next service time and have it done when required. You should be good for years to come.