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Olds 2000 Silhouette Van

I have a 2000 Olds Silhouette VAN with @120,000 miles on it. Runs good - doesn’t leak or burn a drop of oil. The transmission bang shifts (as if under lot) after the engine warms up. The transmission shifts smooth as silk and on time when the engine is cold but as soon as the engine reaches normal operating temperature it starts bang shifting as if the van is under some type of load condition. Any thoughts?

I’m sure that transman knows the “exact” cause of this but I’ll tell you what I have observed when this happens. I have noticed that whenever any GM vehicles do this that the transmission is on it’s last legs. You need to see a good transmission mechanic soon because the transmission will not get any better on it’s own.

Thanks for the response.

What you really want to do is have a local independent transmission shop (i.e. not a national chain operation) scan the computer for error codes. There are some transmission error codes that won’t set a check engine light, so you can’t necessarily go by that.

If you can get codes then you can post them here for advice.

I do know that this van has a GM 4T65E transmission which has had chronic problems with its “electronic pressure control” (EPC) solenoid. You can Google this and find a lot of reference to it. For general overall info about this transmission I have also found this site useful: http://www.tripleedgeperformance.com/New_Home_Page.html

The problem is that your description does match what happens when the EPC solenoid malfunctions - but this kind of thing can happen for other reasons as well.

Has this transmission ever been serviced? - as in getting the pan dropped and a new filter? If not, then a visit to a trans shop is certainly in order. They can scan it, perhaps do the pan & filter which means that they can inspect the contents of the pan. If it does turn out to be the EPC solenoid this does not require a complete teardown & rebuild. It is possible, however, that at 120K a shop might say they wouldn’t want to do anything but that.

Anyway, getting it scanned for error codes would be step one.

Will do.
Thanks.

I too had trouble with this solenoid on my Silhouette…have had it replaced twice, once still under extended warranty and the second 2 years ago at 160,000 miles. There was a GM bulletin on this problem with the transmission.

Thanks for the info. Since there is a GM bulletin for the problem does it mean a GM dealer should fix it for free?
Larry

No the GM dealer won’t fix it for free.

If you shut the can down, wait a minute and turn it back on will it shift normally again at least for a brief time?

What is the service history on the transmission? Did you get the thing scanned for codes or what?

I haven’t tried that specific test but do know the problem only occurs when the transmission is normal operating temperature. If we stop at a store and go back into the van with a slightly cooled down engine the transmission goes back to shifting normally again. The van has been maintained extremely well with regular trans fluid changes by a chevy dealer in years past. The problem was fixed once under warranty but came back after the warranty expired.

Trans fluid changes can mean different things. Do you know whether or not it has ever gotten a new filter? This requires pulling the pan off and is the best way to service it. Don’t trust that a Chevy dealer has done the right thing. They only had to get it to last past the warranty period.

Anyway, its still hard to give any advice without knowing whether or not there are any codes stored. Call around. One shop near me will scan for free. Another I know of asks $25 for the time.

In the meantime, humor me and the next time it starts shifting hard stop (somewhere safely out of the way). Shut the van down, wait 30 seconds and start it back up. See if it doesn’t shift normally for at least a few minutes after that.

Back in Sept. '09 a local Chevy dealer found this:
P1811 - Transmission code
Recommend either overhaul transmission or replace with reman transmission
Overhaul - appprox $2600 plus tax and internal failed parts - (12 month / 12K mile waranty)
Replace transmission with reman - $3266 plus tax with 5 yr / 100k warranty.

I will perform your test tomorrow and get back to you.

Thanks,
Larry

P1811 refers to a problem found in the timing of shifts - in particular that the shifts are taking too long. Taking too long means too much slipping. Too much slipping makes to much heat and accelerated wear on the clutches. When the computer sees this it will command full line pressure to eliminate (the whatever extent possible) the slipping. This is why it slams into gear.

At 120K it might just be that your clutches are worn to the point that they have started slipping. In this case, the computer is more or less just trying to buy you some time by slowing the inevitable. The only solution there is the rebuild.

It is also the case, however, that these transmissions (4T65E) often do have this problem even at low mileage. Take a look at this:
http://www.grandprixforums.net/f21/4t65e-hard-shift-solution-25211.html

In your case, if this problem is new then at 120K I’d be more likely to see a rebuild in your future.

Wow - that is one interesting article on the 4T65E. So a rebuild may not be the case - just a shift kit. It’s worth a try.

Thanks for the info.

Larry

I tried the 5 minute test and it works. The transmission reverts back to shifting smooth again for a few minutes anyway. I approached a local transmission repair shop about installing a shift kit and they said they’d do it but the transmission will be dead in a couple of weeks because of it. I’ll hold off on the shift kit for now.

What reasoning did they give for it killing the transmission? The first guess I would have is them going on the assumption that it produces a harsh “bang shift” that wears or breaks hard parts. A lot of shift kits are meant to be performance mods for people (often young ones) who like to pretend their street cars are race cars.

The shift kits described are not of that type. The Transgo seems to be a common install for rebuilders of this transmission.

That said, I am not a transmission rebuilder and there is a lot I don’t know. My own thought would be that you either a) rebuild the transmission or b) try something else and maybe have to rebuild it anyway. The math is pretty simple - the risk would amount to whatever the kit costs - unless they want to be more specific about what will kill the trans “in a couple of weeks.”

I’m actually curious as to just how many of these transmissions they’ve seen die within a couple of weeks of this mod.