Temporary Transmission Trouble on VACATION!

2000 Montana, 138,000 miles

This was really scary, and it has me worried. I'm currently on my way to a fun family Christmas vacation in South Florida from Ohio.

We had driven about 500-600 miles yesterday, and my GPS had routed us through a rural area of South Carolina. (I think we were on Route 21, if you're familiar with the area.) Sometimes you gotta wonder about these GPS shortcuts.

Anyway, I stopped to fuel up, and when I got back on the road, the transmission immediately started to whine on acceleration and shifted very hard. I think I've heard these referred to as "full pressure shifts" in the past. I had a Saturn once that would throw a code and do this about twice a year. All you had to do was turn the car off for 30 seconds and it would go away. However, it has NEVER happened on my Montana.

Truthfully, I started to feel pretty panicky. I was in the middle of nowhere with my three sons (my wife is flying down on Monday). We just prayed that everything would be ok and I even texted my wife and told her to pray.

After about 30-45 minutes of driving (not much shifting at all), I couldn't stand it anymore and pulled over at a gas station/convenience store. I checked the transmission fluid and it was pink and right on the full line. (IMPORTANT BACKGROUND: I JUST HAD THE FLUID AND FILTER CHANGED BEFORE I LEFT FOR VACATION.)

We decided to get sandwiches and sit for a little bit to see if that might help.

We got back in the van, started it up, and IT WAS FINE. No whining, shifting perfectly.

And, it has been fine ever since. We've stopped and started 2-3 times with no further problems. Shifting smooth and running strong.

We're driving another 4-5 hours today, spending the week in West Palm Beach, then driving all the way back to Ohio.

Any thoughts?

It sounds like a stickey, or a stuck transmission shift solenoid.
Is there water on the roads?
Water, snow, and Ice could short the Transmission shift signal out!

Pay attention to this... It may happen again or if you are lucky it may not happen for a long time.. The 65E has a PCS that controls the transmissions line pressure... For what ever reason the PCM was commanding a Full line pressure shift.. Full line pressure will cause the Trans to whine and shift hard.....

Have a look at these two links:

http://www.automotiveforums.com/vbulletin/showthread.php?t=955854

http://www.automotiveforums.com/vbulletin/showthread.php?t=955891

I can't guarantee that it will solve your problem once and for all, but for $35.00 (incl s&h) it might be worth the effort to try this.

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In addition to above replies, I'd recommend the install of Aux transmission cooler as well. Even if NOT towing a trailer, I'd install an extra cooler to more then 2+ passenger &/or internal cargo hauling usage. My local transmission specialist recommends install of aux transmission coolers in all GM vans. Especially the Montana/Uplander/Venture and Safar/Astro vans - that love to run hot. Cooler ATF the better.

In your hotter climate regions, I'd install an LPD design rated to pull 5,000 lbs trailer. re: http://www.transmissioncoolers.us/Merchant2/merchant.mvc?Screen=PROD&Product_Code=4590&Category_Code=trucool-coolers-hd&Product_Count=2

Hope this helps as well....

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When I replaced the trans in the van, I installed a cooler as I had the front bumper and parts off to replace the condenser, so I took the opportunity to install this cooler..

http://img.photobucket.com/albums/v294/Jr3800/1995%20Pontiac%20Transport/95TransportTrannyRemoval057.jpg
http://img.photobucket.com/albums/v294/Jr3800/1995%20Pontiac%20Transport/95TransportTrannyRemoval055.jpg

This is an older Transport, but had the 3800 V6( Bit of a torquer )... Moving these vans and people or towing these transmissions get hot.. This van actually came with a dual cooler in the radiator... Uses internal heat exchangers on the driver side and passenger side of the radiator... But thats not enough, so I added a decent size AUX cooler as I am in Florida.. Later on I actually went back and installed a slightly larger cooler, about 2 inches wider than the one you see pictured.. This was done well over 1 year ago and the fluid is still red as it can be..

Jrs3800: Great ATF aux cooler install. Excellent pictures (to show others) as well. And, I like your idea of installing larger size aux LPD coolers for hotter climate regions as well. Great work.


My local transmission specialist likes to install a can of Lube Guard in his serviced transmissions as well. Was told this stuff raises the ATF's boiling point and creates better internal lubrication. Thus, reducing the risk of "stuck" moving parts. Not too sure if this is true but, sounded good to me.

For more details, surf: http://www.lubegard.com/C-112/LUBEGARD+Automatic+Transmission+Fluid+Protectant


Hope this helps as well...

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Thanks... I have a cooler on my 95 Bonneville as well... At 184,000 the trans still functions and the fluid stays red...

The Van has been modded... Its far from stock.. Currently running a 3800 III with the 3800 II upper parts... And a 4T60E with the 3.33 ratio... The engine has a Performance cam in it... Lugs the van around quite good..

On of the issues I had was the trans was getting too hot... On a normal basis I am hauling around a motor and Trans, or Concrete or what ever I need to... I needed to have the capability to keep the trans cool... One of the largest issues I saw with these vans especially with the 3800's was that the trans would overheat in a bad way... I have seen a few burned up to the point the fluid was almost black... Very bad...

The newer Vans used a 4T65E, we have been told time and time again that they do not overheat... I never agreed and still do not agree... Heat is the enemy of any automatic transmission.. I was driving a friends car on a cool day( 06 Pontiac Grand Prix ) 3800 V6 with a 4T65E... His car was strange in that it had the full pod for info... I was driving back from Orlando International and set it to Trans temp... On the way back it was 150.....160.... 170.... 180... 190...200....210...217...218.... and this was at 70-80 Mph... 200 or more is hard on any trans... 160-170 is the happy place...

My 95 Bonneville runs about 150-160 on the interstate... Its no wonder with the abusive it has received from me the trans is still kicking at 184,000 miles...

So I am a Fan of adding an AUX cooler...

Jrs3800,

I know what you mean about ATF "running hot". Being "too hot" and for "too long" and it creates inner tranny problems in the long run. While on recent "winter time" VAC, my family drives 7.5 hours south. Nice short drive we often do 4 times per year. Before traveling back home, I always get my BIL's (Brother-In-Law) friend to perform a quick end/end visual inspection. He checks all fluids, belts, any drips and other "quick check" concerns. We always get this free inspection because during 5.0 hours of this drive, there's no Service Centers. Just us and the road. Thus, quick 15 minutes of visual inspection to lower the risk of possible "on road" problems.

During an inspection of our van's front grill area, he looks down and says, "great - you do have an aux tranny cooler - and its the better design kind as well". If wondering, this guy's a certified auto mechanic (who own's his own auto repair shop) and he too recommends ATF LPD aux tranny coolers be installed on all Venture, Uplander and Montana vans as well. Even if the van's are only used for general "soccer parent" driving conditions. And during the harsh cold winter months (like in my usual -20 F temps), we cover the aux cooler as well. Unknown to some, keeping the ATF "too cool" is just as bad as allowing it to become "too hot". Thus, a winter coat (sort of speaking) is also wrapped around our aux cooler during the winter months as well. During the hotter summer months, I remove this extra winter coat (which is thick plastic bag - to eliminate "wind chill" factors).

Good ATF heat chart at: http://www.cpgnation.com/forum/attachments/1088d1261066276-beat-heat-transmission-life-expectancy-trans_life_expectancy.jpg

Good luck with your van and ATF cooler as well....

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A very Hot transmission can cook and damage seals, this will cause you to loose hydraulic pressure.