Thread: 9C1 Transmission Cooler on Grand Prix

Hey all,

Just something I'm trying as a learning experiment. I pulled a factory transmission cooler from a 2004 9C1 Impala (Police Cruiser). Today I decided to put it on my Grand Prix. Install was actually pretty easy. Figure I can drive around this labor day weekend and see what results I get.

Today (before cooler install) went on business trip, transmission temp (viewed with HP Tuners) was 220 peak, 210 average. (About 88* outside air temperature)

From what I've read, this is a perfectly healthy and normal temperature for this transmission. However, I have noticed that as the fluid temp becomes warmer, the PCS / TCC tend to act up more often (oscillating RPM's, hard shifts, P1811 code).... which is pretty normal behavior for a factory 4T65E with 276,000 miles, I would think.

At one time, I had tried putting a 180* thermostat in just for kicks and set fan settings to maintain 185* and watched trans temps. The temps stayed around 190-200* ... so, as one could reasonably expect, with only the radiator to cool, the trans fluid stays pretty close to engine coolant temps. At least that's been my experience. Transmission also seemed to behave better as well.

Not expecting any miracles from my old, tired transmission... just seeing what happens with a little extra cooling.

Did you run it standalone or in series

Originally Posted by theaceofspades

Did you run it standalone or in series

It is run in series with the radiator cooler, just like the Police Impala factory setup. It also uses the factory lines. Trans-->radiator-->cooler-->trans

Should lower temps to about 179 on the highway mine never gets above 194 sitting in traffic with the ac on. Ran like that

Alright guys, was able to take a very similar drive to yesterday, and about 90* outside. Results:

Peak: 205*
Average: 194*

So the 9C1 cooler dropped transmission temps about 15-16*. Not as good as most aftermarket coolers as far as cooling capacity goes. Makes sense, the cooler isn't very big. Stock fan settings under both conditions.

Also had the same surging/etc. as without the cooler. No change there.

I think next I'll try leaving the 195* T-stat in, but change the fan settings to come on at about *200. With cooler I'd expect the trans temp to be around 185*

Why are you using the pos factory cooler anyway you'll never get the numbers you're looking for

Like ^^^

Originally Posted by 91parkave

Why are you using the pos factory cooler anyway you'll never get the numbers you're looking for

I think you missed the point here... it's just about trying something and seeing the results. If I wanted maximum cooling, it's absolutely no problem to get a cheap transmission cooler kit from various vendors. This is just sort of a review of this one specific factory GM cooler.

What I'm saying is you are not fully seeing the benefits of that particular trans cooler. Run the same one in standalone and see where you get.

Originally Posted by 91parkave

What I'm saying is you are not fully seeing the benefits of that particular trans cooler. Run the same one in standalone and see where you get.

Sure, that is possible... but instead of using factory lines, I would cut my own lines and run them. It would also require removing the fittings on the transmission and cooler and installing barbed fittings. Might as well just buy an aftermarket kit for $30.

Keep in mind also, that this is a pretty small cooler. In the 9C1 configuration, it has to share space in front of the condenser with a power steering cooler and oil cooler. It's only intended to be a supplementary cooler. The trans might actually run hotter in standalone.

If there is enough interest, though, I could try running it in standalone as another experiment.

You wouldnt need to remove the factory fitting and lines from the transmission. Just cut the rubber section, slide a barbed fitting in there and add the new cooler

i still run the giant B&M megacoolers post OEM trans cooler.

our oem cooler is quite good, and it has 3/8ths fittings....though you later quick connect guys did get ****ed, thats what happens when the bean counters find a way to cut costs...even if it restricts flow over a standard 45*inv flare.

the oem cooler at least helps your trans get up to temp faster. though with the newer constant viscosity dex6 im sure thats not as much of an issue

Originally Posted by GTP131

Sure, that is possible... but instead of using factory lines, I would cut my own lines and run them. It would also require removing the fittings on the transmission and cooler and installing barbed fittings. Might as well just buy an aftermarket kit for $30.

Keep in mind also, that this is a pretty small cooler. In the 9C1 configuration, it has to share space in front of the condenser with a power steering cooler and oil cooler. It's only intended to be a supplementary cooler. The trans might actually run hotter in standalone.

If there is enough interest, though, I could try running it in standalone as another experiment.

You 97-03 Guys would have to use the factory lines and cut them anyway since your fittings have a check valve in them IIRC. And i know the 9c1 setup well since that is what i have. I run full standalone, and have been for years now, It speaks volumes that my GXP made it over 100K with the factory trans while most couldnt make it that far, With you guys im sure the benefits would be even greater.

Originally Posted by DirtDog

You wouldnt need to remove the factory fitting and lines from the transmission. Just cut the rubber section, slide a barbed fitting in there and add the new cooler

Exactly.

Originally Posted by Turbocharged400sbc

i still run the giant B&M megacoolers post OEM trans cooler.

our oem cooler is quite good, and it has 3/8ths fittings....though you later quick connect guys did get ****ed, thats what happens when the bean counters find a way to cut costs...even if it restricts flow over a standard 45*inv flare.

the oem cooler at least helps your trans get up to temp faster. though with the newer constant viscosity dex6 im sure thats not as much of an issue

04+guys didnt get ****ed at all we have no check valves in our line fittings at all, I made a writeup here http://www.grandprixforums.net/threa...ines-*Updated*

we can simply use whatever -6 out the trans case to whatever line and run like that, I have drilled out -6 port to -8 pushlocs on full 1/2 line to the 9c1 oil cooler as a trans cooler. which allows 1/2 fittings as well.

Still not seeing the logic in turning a snap in/bolt in factory setup into a hack job when aftermarket kits are readily available.

If you believe a 6' x 11' cooler is enough to handle transmission cooling by itself... I'm willing to try bypassing the radiator cooler in a way that I can easily reverse if it doesn't work out.

And good points Turbo. I do run Dexron 6... should be more resistant to both heat and cold than older fluids.

Now, if your radiator cooler is blocked up with crud, I could see there being an improvement by bypassing it.

Originally Posted by 91parkave

You 97-03 Guys would have to use the factory lines and cut them anyway since your fittings have a check valve in them IIRC. And i know the 9c1 setup well since that is what i have. I run full standalone, and have been for years now, It speaks volumes that my GXP made it over 100K with the factory trans while most couldnt make it that far, With you guys im sure the benefits would be even greater.

Are you sure we are talking about the same 9C1 cooler? This is the little dinky one off of the 2000-2005 model Police Impalas.

I plumbed in an Exploder transmission cooler and I'll see at most 183*F. It has mounting ears as well so install was pretty easy.

why did you decide to use the pc1 engine oil cooler instead of a 9c1 trans cooler or an aftermarket B&M/knockoff?

we only took the 9c1 engine oil cooler adaptor, the lines, fittings and cooler didnt look all that enticing for the 442, figured on aftermarket as being better.
-10an Oring fittings thread right into the oem 9c1 engine oil cooler adaptor, if you unscrew the oem quick connectors that are known to leak.

any pics?

Originally Posted by Turbocharged400sbc

why did you decide to use the pc1 engine oil cooler instead of a 9c1 trans cooler or an aftermarket B&M/knockoff?

we only took the 9c1 engine oil cooler adaptor, the lines, fittings and cooler didnt look all that enticing for the 442, figured on aftermarket as being better.
-10an Oring fittings thread right into the oem 9c1 engine oil cooler adaptor, if you unscrew the oem quick connectors that are known to leak.

any pics?

Cause i had been doing some googling on using oil coolers for trans coolers, and since i already had it laying around, i wanted to try it. Filling that thing sucks up about 3/4 quart of fluid, more so than my previous cooler. And living in AZ it has been put to the test with ambient temps up to 112degrees i have yet to go over the 187 mark. and thats in traffic jam weather. Im very impressed with it for what it was worth from the junkyard.

And no quick disconnect lines, I junked all that crap the moment i got the cooler setup. Right now its all -8 from the cooler to remote trans filter -8 and to the trans with the -6port to -8 male connectors.