Cold tranny fine, hot not!

[catesja]

Ok, here goes; I have this problem that when the transmission is cold it shifts nice and easy, after it warms up and the longer I drive, the harder the shifting gets. I changed the fluid and filter 2 weeks ago. I checked the fluid yesterday before a trip and it was purple colored. I seems that the tranny is overheating and burning the fluid. Where should I look for a overheating problem? Plugged cooling lines? What would be good for flushing the system, but not over doing it? Just fluid?

Thanks!

Jeff

[blazes9395]

I don't know if you'll see this quick enough, but if you do and you still by chance still have a working transmission, get it looked at ASAP. Is the shifting hard through all shifts? Does it go away after you shut the van off and go start it again. When was the fluid changed before that?

When your transmission starts shifting hard, it usually because the van's computer has sensed that your tranny is slipping, by default the van's computer will stop any shift adapting stratgies used, and will command max line pressure. This will usually set you SES light, but NOT always. Driving it like this will cause your transmission to self destruct.

[catesja]

Originally Posted by blazes9395

I don't know if you'll see this quick enough, but if you do and you still by chance still have a working transmission, get it looked at ASAP. Is the shifting hard through all shifts? Does it go away after you shut the van off and go start it again. When was the fluid changed before that?

When your transmission starts shifting hard, it usually because the van's computer has sensed that your tranny is slipping, by default the van's computer will stop any shift adapting stratgies used, and will command max line pressure. This will usually set you SES light, but NOT always. Driving it like this will cause your transmission to self destruct.

The dealer said it was changed when they did the used vehicle inspection, but I fould several other things that weren't repaired or replaced when we bought it. So I am unsure of the last time it was changed. It is a 2000 Montana with 96,000 miles on it. We bought it with 38,000 on it. So the usual 60,000 change according to what I knew.

I took it to Aamco, they told me the TCC and shift solenoids need to be replaced. They recommend a main valve body replacement, as well as a pressure solenoid replacement. Total $1200. This is assuming that once they get it apart that there isn't anything else wrong. Then they told me that it could be as much as $2800 to get it rebuilt or replaced with a rebuild. I have ordered a tranny rebuild manual, the solenoids from Napa, and will be doing that repair in a few weekends. However, since the codes were pulled and the computer reset by Aamco, the van has shifted perfect. Even after getting it all warmed up and driving it a good 40 miles or more.

Aamco said there was a small amount of clutch material in the fluid (my assumption is a normal amount) that is when they said it could need a rebuild, and that a few gears may be broken. No broken gears that I know of, it shifts fine, so I think they want my money and as much of it as they can. So if I am going to end up replacing it, then I might as well drive it until it dies. It will be the same price in the end!

Anyway, we will see in a few weeks!

[blazes9395]

You can buy a fully rebuilt valve body tested, with new sensors and this usually solves the problem you have. this depends though, on how long/bad the transmission was slipping, and running with line pressure. Some trannies that had this problem, a new rebuilt valve body can be installed, and you can get another 100,000 out of it, others, the damage has been done, and has to be rebuilt.

Take a look at this, anytime I have to do any transmission rebuild, these updates this site provides is a must. Scroll down to the 4T65E.

http://www.transmissionspecialty.com/parts/DM/GM.htm

Usually its the p1870 code thats the most common.