I found nothing anywhere that tells what the A6 line pressure is for the coolant lines. I'm not looking for guesses, so does anybody have that specific knowledge?

I'm also looking for pics of the stock interior cooler that's inside the radiator specific to Corvettes. Anyone?

 

The fluid in the cooler circuit has no pressure control device, only volume control. Since line pressure is a completely different circuit from the cooler circuit, I'm not sure what you're trying to ask.

Maybe a few pictures will help...this shows the common functions for all ranges:



The following three pictures are close ups of the torque converter and different valves in the above picture:







The last one shows the volume control (valve 3B, TCC Control Valve) which regulates the volume through the "cooler fd" circuit (where "fd" means "feed").

After the fluid goes through the cooler, it returns to the pump cover where it's directed to the center lube circuit to provide lubrication to all the parts in the center support (bearings, gears, bushings). From there, the fluid returns to the pan.

This will give you a better idea of the description above:



The pressure in the cooler circuit is going to be the back pressure created by the amount of fluid flow through the cooler and lubrication circuit...I'm not sure you're going to find a "specification" in any publications. Maybe just make a "tee" fitting and be the first to measure the pressure in the cooler circuit. Hope this helps.

PS You can get books about the 6L80/90 from several places. I got mine from this company:

http://www.transmissioncenter.net/6l...arts_6l90e.htm

Scroll about 3/4ths of the way down to find the two manuals...they're both very good and essential to understand how the 6L80 operates.

 

[QUOTE=glass slipper;1577551804]The fluid in the cooler circuit has no pressure control device, only volume control. Since line pressure is a completely different circuit from the cooler circuit, I'm not sure what you're trying to ask.

The pressure in the cooler circuit is going to be the back pressure created by the amount of fluid flow through the cooler and lubrication circuit...I'm not sure you're going to find a "specification" in any publications. Maybe just make a "tee" fitting and be the first to measure the pressure in the cooler circuit. Hope this helps.
QUOTE]

Thanks for the information and circuit diagrams. Not that I understood everything, but I now have a better idea how the fluid flows.

I probably worded the question wrong and should have asked what the maximum pressure would ever be experienced in the cooler lines.

The reason is to make sure the lines to an additional cooler are capable of the pressures encountered. I've seen simple rubber with hose clamps and reinforced stainless braided with AN fittings being used. I've heard that some lines have split and I don't care to lose a transmission that way.

I've asked at transmission repair shops and had answers from "not much" and "maybe 20 PSI" to "at least 100 PSI" and "it could spike to as high as 240 PSI under the right conditions".

I also asked at Hayden and was told they just design/test to exceed worst case conditions for the highest pressure attained in transmissions.

I looked in the Corvette shop manuals and even though the diagnostics section refers to too much or not enough pressure, there is no place I found that indicates what the desirable pressure is.

It just kinda left me curious to what my minimum standards for the lines should be. I just don't want to put in 2000 PSI line where 30 PSI is considered overkill. Putting a gauge inline requires the same concerns.

 

[QUOTE=HOXXOH;1577555050]My question: Is there a pressure regulator anywhere in the circuit?

 

Yes, it's valve (1a) in the pictures below.





Can you see the Line Pressure Control Solenoid (1c) in the first picture and how line pressure is controlled by varying the pump output volume?

 

Ok, I see what you're after now. If there was a blockage in the center lubrication circuit (which is after the cooler), it's possible the cooler circuit could see the max line pressure of 300 PSI if the converter feed limit valve also failed. (The max line pressure specification of 300 PSI comes from the FSM...that is what Hayden is talking about when they said they "design/test to exceed worst case conditions for the highest pressure attained in transmissions".) The converter feed limit valve is a pressure reducing valve (fed by line pressure) to limit the pressure in the converter circuit and is valve (3a) in the pictures below:





I know you weren't looking for guesses but if I had to guess, I'd say the cooler circuit wouldn't see over 50 PSI at any time with all valves working correctly. You would have to have multiple failures to achieve 300 PSI in the cooler circuit and at that point, a ruptured cooler line would be the least of your worries.

 

I see the problem that could result, but agree that by the time a hose bursts it's been preceded by other damage.

I had already purchased 3/8" Nitrile hose to SAE 30 R7 specs rated at 50 PSI, so I guess that my guess approximated yours.

I feel much more comfortable now. Thanks again.

 

When I put an extra cooler in our C5, the biggest hose problem was finding something locally that could take the heat- up to 270'F, possibly.

 

Good point. Just because a hose can take the pressure doesn't mean it'll handle the heat requirements.

The 3/8" hose I'm using is rated -30 to 257 F. The highest temp (in the trans) I've ever seen is 235 with the stock cooler. If it ever ran sustained above 257 long enough to compromise the hose, I would have already killed the trans. The fluid is cooling quite a bit on the trip to and from the cooler on the stock lines, which adds an additional safety margin.

Goodyear makes a 3/8" hose designed specifically for transmission cooling. It has a heat range of -40 to 300 F and a WP of 400 PSI. I didn't bother to ask price, as I thought it was overkill for my needs.

The 50 PSI rating is also for sustained pressure and has a minimum burst strength of 250 PSI. Of course like Glass Slipper mentioned, by then the problem is far beyond just a hose splitting.

 

I finally had to order some flex line from B&M, could find lots of high pressure stuff locally but not high temp.

The A6 will give you a DIC warning at 270'F, and the recommended cooldown is to 230'F or less.

So, you could experience anything up to 270', probably a little higher, without trashing the tranny. Just don't keep it at those temps. I would not use anything that was rated less than 270', and would like to see it rated for 300'. There is probably some deterioration over time, you don't want to be changing the hoses every year.

Good luck on yours!