Chevy & GMC Vans

Sounds about right to me. See if you can find the source.

Meterpig wrote:They also say "fluid comes out hotter than the radiator". OK, so my radiator is running at 190-200 degrees. That's a lot hotter than I want my tranny to run consistently.

The engine is running around that temperature. The "cold" side of the radiator will be lower than that, I'm guessing around 150-160. The cold side of a radiator with a higher cooling capacity will run colder but the engine will stay the same temperature because of the thermostat.

Exactly, Break. The trans cooling loop probably has insufficient area, and there is no forced "mixing" of coolant in the radiator when the thermostat is closed, so the heat transfer out of the trans fluid and into the engine radiator is limited.

Hey guys. I need a bit of plumbing help. I want a diverter valve for my transmission cooler. Something like this...



But I don't know the various dimensions, such as thread pitch, size, taper. Also what size and kind of hose to get. I think the Tru-cool fittings have 11/32" barbs.

EDIT: maybe it would be easier to just use this bypass valve.

The Tru-Cool LPD coolers have a built in bypass valve! What model is yours? It may have it.

"When Automatic Transmission Fluid (ATF) is cold it is viscous. The unique Tru-Cool design allows the colder,
thicker ATF to flow more efficiently through two open bypass channels positioned at the top of the cooler. As operating temperatures increase, the ATF becomes hotter and thinner. It is then directed through the core where it is cooled. Tru-Cool’s highly efficient cooling technology combines improved protection against lube system failure with optimal heat transfer."

Lifted,
I have an LPD4590. It doesn't have a valve per se, but yes the cooler, thicker oil is supposed to go through the bypass channels. Still, I'm finding that even now in the warmer weather, the fluid doesn't reach optimal temps during daily driving.

What temp do you want to see? I always figured the cooler the better. In my Ram with the stock cooler, I almost never see more than 125 in the winter unless running with the plow. In the SPB, it would run under 150 most of the time.

I did a lot of research on tranny temps before I got my cooler, and I think optimal running temp is 70-90°C (160-190°F). That's roughly the range of temps I had with the factory config during normal driving. The only problem, as you all know, is that they go way beyond that in extreme situations. Elsewhere on the forum, I came across someone mentioning that GM recommends 80°C (180°F). The bypass valve that Long makes (manufacturer of the LPD coolers) opens at about 80°C as well. Some transmissions and coolers have built-in bypass valves, and big trucks even have fluid heaters for cold climates! After all, even our tranny fluid runs through the rad which warms it up to around 90°C.

I have noticed that in the morning when everything is cold, the shifts are harsher. We also discussed before about TCC activation, but that's only at very low temp. I could be over-reacting. Maybe it doesn't matter as long as the transmission is doing its job. Would be nice if the GM techs on the forum could speak to this.

May I suggest...

http://www.thetransmissionfluid.com/

It's what I do. Along with a Wix Filter...

Yummm, Good Stuff.

Jim

How much does that stuff cost?

timelessbeing wrote:How much does that stuff cost?

I just did a Wix Filter and a 5 qt pan drop for about 75 bucks. About 50 bucks less than the trans shop charged me on my last service.

Well worth it. About 10 bucks a qt.

I paid $2 per litre of regular ATF (that's a little more than a qt). The bypass valve is about $30.

Quantity vs Quality...

What is your service interval with your 2 dollar oil?

Jim, I don't have a regular interval but I believe the manufacturer recommended 48,000km is fine for average driving. My tranny has 250,000km and is still going strong. How often do you service yours?

timelessbeing wrote:I did a lot of research on tranny temps before I got my cooler, and I think optimal running temp is 70-90°C (160-190°F). That's roughly the range of temps I had with the factory config during normal driving. The only problem, as you all know, is that they go way beyond that in extreme situations. Elsewhere on the forum, I came across someone mentioning that GM recommends 80°C (180°F). The bypass valve that Long makes (manufacturer of the LPD coolers) opens at about 80°C as well. Some transmissions and coolers have built-in bypass valves, and big trucks even have fluid heaters for cold climates! After all, even our tranny fluid runs through the rad which warms it up to around 90°C.

I have noticed that in the morning when everything is cold, the shifts are harsher. We also discussed before about TCC activation, but that's only at very low temp. I could be over-reacting. Maybe it doesn't matter as long as the transmission is doing its job. Would be nice if the GM techs on the forum could speak to this.

Your right TB.It doesn't matter.My two cents is it is more important to know what is the temp.I mean too hot over being too cold.