Transmission Help

[Redlegger]

I have a 2002 GCS that I recently bought with 90,000 miles on it. It replaced another one which had 159,000 miles that my wife totaled. I never had any tranny problems with that one or the other 2 GCS's that I had that were company cars, but I only had them till 60,000. I just turned over 100K and I've notice when the car is cold it slips a little at start-up and until it gets warmed up. It has now started to clunk when the brake is depressed just before the car comes to a stop. How much time do I have ? Any thoughts.

Thanks.

[v8carreragts]

The clunk you feel is the trans downshifting. It shouldn't slip when cold. The first thing I would try is doing a complete fluid flush and changing the filter. The problems you have could be from incorrect fluid. You need to use ATF+4 fluid and a name brand filter.

One thing these transmissions do not tolerate is the wrong fluid. It is very common for shops to use Dextron and say it will work fine. Don't believe them. If you do it yourself, Walmart has it for $4.45/qt. It is expensive but you can be guranteed to have problems with other fluids.

[Redlegger]

What is the procedure to drain ? I used to work on my cars years ago, but haven't done much except light bulbs on my caravans. I was told by a mechanic one time that if the fluid hadn't been changed by 100K not to do it ? Thoughts ?

[N8SBlaze]

I have an 01 GCS with just over 100k miles on it. I had planned on changing the trans fluid this fall but it got real cold out and decided to put it off until spring. I bought the ATF 4 fluid and filter/gasket kit from NAPA and it came with simple instructions. My understanding is that by simply dropping the trans pan and changing the filter will not get all of the trans fluid,but that a flush will. And I have been told that trans flushes should not be done on high mileage vehicle if they have not been part of regular maintenance, but that dropping the pan and changing the fitler is ok. I am not a seasoned mechanic so other opinions would be welcome.

[v8carreragts]

My last van was a 94 T & C 3.8L 4 spd. with 144,000 miles. It started to shift late and hard into second and doing a complete filter change and flush fixed it. I worked flawlessly after that for about a year. (when I sold it)

To do the complete flush you first change the filter and of course the fluid from the pan and refill it. Do not start it yet. Disconnect the cooler out line from the cooler (the one on the drivers side of the trans) and extend it so it reaches a container to catch the fluid. Run the engine until you get about 3 qts out then shut it out and add 3 qts. Repeat this process until you have added a total of about 10 qts. Then reconnect the cooler line, restart the engine and recheck the level. Add as necessary and check that the cooler line and pan does not leak. That's it. You will have changed the most fluid possible without dissassembling the transmission.