When I warm up the truck in the morning do I need to idle it in neutral like I had to on my 02, or will it flow fluid in park.

 

You know it! The 48re only pumps fluid in neutral and of course all the gears. Get the gauges in that baby so you can check things out.

 

Ok, NOT trying to start a war or anything, how or why doesn't it pump any fluid while in Park?? Does the front pump have some sort of a relief valve or bypass?

 

I have never thought about that! Are you saying that I should set my parking brake (which I do anyway) and then put the truck in neutral and let it idle to warm up? Does the tranny need that?

I warm the engine up, but I never thought about "warming" up the tranny. Is this really necessary or especially helpful on auto trannies?

 

I know that this was the case with my 47re. When I had the tranny built they "fixed that", not sure on exactly how.

I do know this though. Remember to put the "EMERGENCY BRAKE ON!!!!"..... Not that I would ever do that.........and have the truck back itself out of the garage........and down the driveway..........into a TREE!!!............never!

 

That's why I'm asking. Just doesn't make sence to me. So if it doesn't pump fluid while in park then I should be able to disconnect a trans cooling line and no fluid will come out?? What is stopping the front pump from pumping? As long as the engine is running then the pump is turning/pumping, right or wrong?

 

I'd say fluid moves while in park, same as neutral but not through the entire tranny

 

Torque Converter is turning...which means that the pump is turning...

However, fluid is not being applied to the clutch packs. Fluid however is flowing from the pan to the TC, back to the cooler, back to trans.

 

not sure on the 48 RE, but i know for certain it did not pump in park on the 46 RE or 47 RE. most shift kits fixed this. AFAIK, Mopars are/were the only trannies to do this....no idea why though.

 

I warm the engine up, but I never thought about "warming" up the tranny. Is this really necessary or especially helpful on auto trannies?

 

It pumps just not through clutch's etc.Its in the valve body.Modified valve bodys allow fliud to pressurise through entire unti.

 

Can somebody that knows, please answer this question? What is the benefit?

My trans seems to work fine in the cold.

 

TexasCD... On start up (start in park first) idling your truck in neutral will "circulate" the tranny fluid thru the internals. It will not warm up the fluid. The benefit is lubrication of tranny. No harm done idling in park and then driving away. It's just a feel good thing to do with a stock valvebody on the 48re. Hope this helps abit

 

Thanks N.Johnson........That does help.