transmission cooling questions

[Tapani]

The temp gauge and fan control still to be done.... I installed the thermostatic bypass valve and finished the cooler/fan installation too.

I wonder if there's enough fresh air inside the front fender? It should be a high pressure area when the vehicle is moving - it is directly connected to the radiator front area.

/T

[dannmarr]

Which way is your cooler facing? Looks like to the driver side. I have mine facing the front bumper to get more air flow.

[dannmarr]

Sorry, I just realized you have a fan. I don't.

[Tapani]

Update:

Drove the SVX first time after the q-panel and tranny cooler cooler work....

The distance required for the TCC to lock is now half of what is used to be.... 9 km instead of 17-18km, so the original cooling setup was too much under these conditions anyway.

I monitored the fluid temp with a lap top. The Marshall temp gauge is still being shipped from California... The temp never got above 171F in the pan. The conditions were the easiest possible, though. Mostly just cruising and 32F ambient. The car was garaged at room temp (as always), so I did not start at freezing point .

The opening temp for the bypass is 180F so I guess the flow never reached the cooler this morning.

/T

[Chucksta]

Does your fluid pass through the radiator first, and then through the cooler?

[Tapani]

No,

The radiator cools it too much in cold ambients and it is not a part of the system anymore.

I have a bypass valve, which bypasses the cooler until the fluid is around 180 F, i.e. it just routes the fluid back to the pan.

The highest temp I saw on the laptop yesterday was 185F. The Marshall gauge (with the output for the fan relay) is on its way.

/T

[Chucksta]

Ummm.. Ok, Then I'm a bit lost. Shouldn't the torque converter have locked up as soon as you were at the necessary speed? You keep her in a heated garage ( room temperature, approx 22 C. / 72 F.), I thought the threshold for lock up being available was 10 C. / 50 F. / .. Or are there different specs for different models? JDM, USDM, etc.

I'd thought that if you'd routed the fluid through the rad first, that the fluid would have been exposed to coolant that was getting ambient air flow ( 32 F. / 0 C.), actually cooling down from "garage" temperature, while there was limited flow through the rad until the thermostat cracked open. But as you've routed directly through the cooler, this is obviously not the case.

Also, as obviously, I'm missing something here. Is the lock up temp signal from the transmission temp sensor or the ECT sensor?

Thanks,

Chuck.

[svxfiles]

TQ lock up temp is 150°f for the US models.

[Chucksta]

Well then.. That'll teach me to believe everything I read on the web

[92 SVX]

Originally Posted by Chucksta

Well then.. That'll teach me to believe everything I read on the web

I think you read a typo, they left off the 1

[svxfiles]

50°f is the required temperature for shifting into fourth gear.

[steveherman]

So i am hoping to do this today.
I got a 7.5" X 12 X 3/4" from hayden.
Before I start i have a few questions.
I am gonna mount it on the condesor like svxfilles suggested.
Left or right side? in front of condensor or back?
How can i drain most of fluid?
Is the subaru hp fluid considered best stuff to use?
How many quarts do i need?
What size hose as i am planning on replacing the hose also.

[NiftySVX]

Originally Posted by Tapani

Update:

Drove the SVX first time after the q-panel and tranny cooler cooler work....

The distance required for the TCC to lock is now half of what is used to be.... 9 km instead of 17-18km, so the original cooling setup was too much under these conditions anyway.

I monitored the fluid temp with a lap top. The Marshall temp gauge is still being shipped from California... The temp never got above 171F in the pan. The conditions were the easiest possible, though. Mostly just cruising and 32F ambient. The car was garaged at room temp (as always), so I did not start at freezing point .

The opening temp for the bypass is 180F so I guess the flow never reached the cooler this morning.

/T

Interesting to see how it performs without any sort of device in the cooling circuit. I would be curious to see if the transmission would be able to maintain temp at speed with TC locked. When I had the old cooler without a fan mounted in front of the radiator, it would overcool the fluid and the TC would actually unlock on the freeway. At that time I was driving on a relatively flat road where the car would cruise in 4th lockup for 100 miles. It was even more annoying than usual then as it would lock and unlock every few minutes. I even had it come out of 4th one time when it was close to 0f outside with a headwind.

Let us know if you can perform a similar experiment. I do not know if they have stretches of road like that where you are or if you drive the car on them. I would theorize that the radiator adds a small amount of heat to the ATF (enough to keep it above 100) as I don't see the heat generated by the pump and friction, transferred to the metal pieces of the transmission from the engine, etc. to be able to keep the fluid warm enough.

In a nutshell, I am curious to know under which circumstances the heat transferred to the ATF by the coolant in the radiator (call it x) is of a value greater than the capacity of the heat exchanger portion that will cool it back down (Y).

Seems to me that the system would be designed to have the following properties:

Rough assumptions for ATFT (Z), assuming AMB temp is 0-100f, ECT 195-212f

System as designed:

X+Y=Z+ such that Z<100

X+Y=Z such that 150<Z<178

X+Y=Z- such that Z>178



Obviously such calculations cannot even be attempted without a set ambient temperature at the least, but since ATF dexron II/III is not much sensitive to temperature in the -50 to 280 ish it doesn't matter much.

This would beg the question as to why even heat the ATF at all, which is asked frequently. My main response to that question is that the fluid is designed to operate in the range of 150-200 and that is not crucial but in a transmission such as the 4EAT it is important to have "all hands on deck" as far as helping that high clutch stay lubricated, sticky, and applied.

[Tapani]

Nate,

Pls see my post in the transmission mod area - I recorded just what you asked. I think the bypass was recirculating all the way while at highway speeds.

The bypass starts to "close" at 160F and is fully "closed" at 180F.

Tapani

[steveherman]

So i am hoping to do this today.
I got a 7.5" X 12 X 3/4" from hayden.
Before I start i have a few questions.
I am gonna mount it on the condesor like svxfilles suggested.
Left or right side? in front of condensor or back?
How can i drain most of fluid?
Is the subaru hp fluid considered best stuff to use?
How many quarts do i need?
What size hose as i am planning on replacing the hose also.