RacerX

I dont know who you are bringing it to. There is no transmission in creation designed to run on thick black smelly fluid. Fluid only gets to be thick black and smelly from being overheated for long periods of time. And in your case, a 2009 van with 84K? The fluid most likely was NEVER changed. A young truck with high miles? Anyone who sees this in a pan is just wasting time for there is no cure or fix besides R&R the transmission. Look at new trans fluid and notice the difference, bright red and real fluid-like, like strawberry colored pancake syrup. No thick goo and stinky and so on.

And finally who cares what the gauge says if the fluid is burnt? The gauge wont tell you that.

WHat you need to do is watch the tachometer if you have one. If the transmission is overheating WITH an external oil cooler mounted in front of the radiator? Then it isnt shifting. I bet that you re stuck in 2nd. And on the highway the Tach says like 4000 RPMS.

And stop and start hilly driving isnt a real way to tell because the road surface will put throttle pressure over governor pressure and intentionally keep the car from upshifting on hilly terrain.

And besides a dealer could put the car on the Scantool and test the solenoids in the case and also the lockup solenoid on the converter which to me is all the Tow Button actually does.

RacerX

A. the fluid is burnt, Elvis has left the building

B. Additives only treat the rubber seals inside the case. They will swell the seals, making it appear like you have firmer shifts, until the seals lose all their flexibility and blow out leaving you with no line pressure in the affected circuit(s)(which is pretty much everything isn the valve body and in the case 3rd Gear drive servos and upshift apply piston and Reverse piston in most automatics)

C. If the fluid was foaming it will be still be carried to the cooler it would just bubble out of the fill tube or the csase vent if this car had one. American cars arent like Europeans cars, you dont have to fill it precisely because the excess pressure always blown off the path of least resistance(the fill tube).

D. In your example, the condenser made from the same material as the oil cooler is and couldnt exchange that much heat to overheat a transmission running down the road at 50-60 mph but not overheat the engine? YOu know how much air flow is passing through the radiator at this time?

Tacey10

Thanks for the excellent replies. This forum rocks.

A couple things I have done:

I discovered that my new (to me) truck does have a tach. The instrument panel has a switch that I can toggle through to different functions on the odometer pod (this is also the same readout area where my "HOT TRANSMISSION IDLE ENGINE" readout is). I watched the tach today as I drove around, and I do have 4 speeds shifting. Under light throttle and fairly level ground, it will shift at around 1800 rpm through all 4 gears, ending up going around 60 mph in O/D, with rpm at around 1400, I think. So she is shifting. The shifts seem pretty firm.

Also, I stopped at my local repair shop where I've had other vehicles repaired over the years. The owner seems knowledgeable about trannys, but this one is a little newer than what he usually works on. He does have a few contacts at new Chevy/GM truck dealers' repair shops. He called them with my situation, and they said that Chevy has had some reports of faulty tranny oil coolers in the 2009's (the coolers that are part of the radiator). So my next call will be to a dealer that does a lot of cargo van business. I do not know if there has been a tech bulletin out on the issue, but I'm gonna ask. This may explain the history of my tranny heating/overheating/blackened fluid.

The plot thickens...

Thumper_ehhhhh

Im with the camp of if it was black thick and smelly shes toast. Concider yourself lucky its working. I had that same problem with one of my older astros. I got another 6 months out of it before I was stranded. Over the years i've had to swap out 3 different trannies in different vechiles. I thought my tranny was shot in my last van and had it checked out and it turned out to be a faulty sensor. They could have soaked me for a new tranny but didnt. The only way to know for sure about if it really is over heating is put a guage on it. there are many gauges that plug into your obd2 port. The tow haul button just changes the shift pattern in the transmission for towing. Your gearing is a hwy gear not meant for towing . I asked my tranny shop about towing in 3rd vs d. I was told keep it in d unless its keeps searching and jumping to 3rd but because of your gearing I agree keep it in 3rd. The trannys are built better now than the ones in the late 80s early 90s. Odds are your running the 4L60E transmission. Used to be called the turbo 350.

RacerX

Also go online and look up the shift vs. rpm range. I think your shift points are too lows, you should be in 3rd like 2100 RPMs and then in fourth around 1800. I find it hard to believe that your transmission is overheating but the engine isnt IF the radiator is faulty. That would mean the radiator is empty or full of WATER(and not Antifreeze). You would notice that more than a hot transmission.

Tacey10

RacerX the engine temp reads between 185-205 degrees. We have had some really cool air temps lately. I agree that if the radiator was bad, the engine would be running hot also. But, I am not at all educated or experienced in these newfangled cars. That's what you guys are for!

I have an appointment at 8AM Thursday at a Chevy dealer who is going to plug my van into the diagnostic computer. Maybe we'll get somewhere then.

I haven't had any problems with my vehicles lately so I guess I was due for a headache or two.

in2pro

Lets be civil, this forum is all about question, answers and ideas...

RacerX

I am not being incivll only saying that there are many many things that could be the cause and ALL of them are expensive to remediate. So in turn lets concentrate solely on what the most probable cause is using the information we have at hand. I seldom would want one to pay the $150-200 diag fee at a dealer and then be prone to upsell BUT I m sticking to the conclusion that a 2 year old car with high miles, 84K has a gone baby gone transmission. The smelly black thick trans fluid only confirms this.

Tacey10

OK I went to the dealer this morning. They say that probably the trans needs a rebuild or better yet get a GM remanufactured one and get a 100K warranty. Charged me fifty bucks for the opinion.

I had work to do this afternoon. I ran the truck with about 600 pounds of cargo 90 miles, 80 of it on the superslab. I ran with the tranny in the "3" position all the way except the last 2 miles, which were hilly and two-lane. I set the speed control at "55", which put my RPM at 2100. On this hilly highway (remember this is southwestern PA), the "HOT..." message never came on. When I arrived at my exit, with only 2 miles to go, I shifted into "D". Within a half-mile, the "HOT TRANSMISSION IDLE ENGINE" message came on!!! Holy schikies! I stopped and idled it for what seemed like 10 minutes, and the light went off.

About 3 hours later, I returned home repeating the "3" position, but this time the truck is empty. All cool. Light never came on.

It seems this "heating thing" only happens when the tranny is in "D" and either pulling a trailer or carrying cargo.

Hmmmmmmmmmm.

I want my old '64 Dodge van back.

Thumper_ehhhhh

When you get the new tranny your problems will be solved. Keep it in third if you dont intend on changing your rear gears to 3.73. They are better for towing. I like the 100k warrantee as long as thats on top of your current milage.