kenholio

116k trans has always shifted fine with no issues

Cliff Harris

You press a magic combination of buttons to get the dash to display the trans temp. it's sorta like displaying the trip odometer. Like I said, my C6 will do it -- don't know about your car.

desertmike1

Stick a GoPro under the car, and take it for a drive..

Churchkey

This probably does not apply to GM cars, never encountered a converter drain plug on GM's. If the converter has a drain plug insure that it is tight.

The converter may be fractured @ the weld line. Heat expansion + centrifugal force = a leak @ higher rpm.

A leak will never be found if 2 quarts of fluid have been dumped under the car, to much mess.
Clean the trans thoroughly, wrap a white rag around the dipstick fill & if the trans has a vent put a rag around it.

With the trans up to temp make a short high speed run & check for a leak. You may need to lengthen the speed run each time until the leak reappears.

If unable to determine the leak source clean the trans & paint it flat black. Follow the oil track to the source.

kenholio

Wish there was a magic combo for this

kenholio

Going to the shop in the morning to check transmission and factory transmission oil cooler, will update when I know.
What is the factory capacity for the factory oil cooler ?
I will need to double that value if I bypass it

kenholio

So he says the main seal needs replaced and that it only leaks in OD when it makes the most pressure ?? Though reverse made the most pressure, guess its second opinion time

Cliff Harris

These are the pressures I measured on my MD8 Corvette 700r4 with a 0.500" boost valve (stock is 0.472", as I recall, so these pressures are higher):

As you can see, 1st and 2nd have the highest pressures. This means putting the shift lever in the 1 or 2 position, not when the trans downshifts while in D or OD.

kenholio

thanks for the numbers, mine only leaks in OD at speeds over 60, picking it up tomorrow, will post what he said needs to be done to her.

kenholio

Front pump seal leaking, leaks more in OD when the torque converter dumps the fluid out.
ATP Part # CGS31 Overhaul Kit $ front pump seal and bearing and fluid $118, labor $800
Time for google searches, can's be that hard to do it myself

Cliff Harris

That has nothing to do with OD. It's the TCC (Torque Converter Clutch) that dumps fluid when it engages. It works backwards from what you would expect. Fluid pressure holds it OFF and the fluid is bypassed to engage the TCC.

You have to take the trans out. Have fun. I've done it 4 times. It's one of the jobs I really hate on this car. It's a lot of work and takes a lot of time.

kenholio

so is there something i will also have to do to the tc ?

QuickGlass

I had the same problem. I changed the front pump seal myself, it leaked again when hot. I had the transmission professionally rebuilt. It leaked again a year later, right after the warranty ran out.
The seal that leaks is an o-ring between the pump and case.


For me the trans would leak only on the highway after I've been sitting in traffic. My guess is that the radiator and trans would heat up in traffic. When I went on the highway the fluid would cool, cooling the pump, but the case would stay hot. Increasing the pump to case clearance causing a leak.

I added an external trans cooler and haven't had the problem again for over 7 years.

Does yours leak only after getting very hot?

kenholio

Let it run in park for a hour yesterday and no leak, went for a ride and then it leaked after a high speed run in 1st and 2nd. Wondering if i need a transcooler, but that wont fix the problem by itself ?

QuickGlass

Would yours leak if you didn't let it idle for an hour?
If it's cold and you drive on the highway, will it still leak?

kenholio

no leak at idle, hot or cold.
have not tried cold on highway, will try that today.

kenholio

Drove a mile to get gas, jumped out on the main road and opened her up for a quick high speed run, no leaks. If I do the same thing after the engine has warmed up it will blow out oil everywhere.

QuickGlass

Could be a bad o-ring from age or the trans is just getting too hot.
You could try installing an external trans cooler, fairly cheap and easy to install. Plus good for the trans.
If you want to change the o-ring yourself, trans removal is a bit of work.
When removing the pump, keep the trans standing on the tail. Don't lay it down.

kenholio

Yeah adding a external trans cooler can't hurt.
Why not lay down the trans ? If I pull it, I might as well throw a rebuild kit in it vs just replacing pump seal o-ring.

QuickGlass

If the trans is on its side when the pump is removed, the input shaft will slide out and the bearing at the end will move out of position.