Engine/Transmission (1994 - 1998) Transmission cooler/heat exchanger

[Loghead]

'97 4x4 AT



I'm relocating the heat exchanger from beneath the turbocharger to the crossmember beneath the radiator - so it will end up being behind the bumper.



I removed both of the steel transmission fluid lines, and then the flexible (trans fluid) line that attaches to one end of the cooler. It seems there's a check valve in one of the fittings (lower?).

It so happens that the flexible line was looking a bit cheesy, so if I need the function of the check valve I'll need to buy a new one, and the only way they seem to be available is with the pre-bent steel tube attached.

I'd rather not do that since I'm switching over to the Jeg's Push-Lok hoses for the whole trans cooling circuit.



Since the heat exchanger is being moved from a rather high (and awful! #@$%! ) spot to a rather low spot, will I even need the check valve?

 

[cerberusiam]

The check valve is to prevent converter drain back, if you fix the problem in the trans it is not needed. Not really neede deven if you don't fix the TC cahrge issues, just go to neutral for 30 seconds before starting out. Removing it is uually a good thing because it is garbage trap and will reduce cooler flow.

 

[Loghead]

Thanks for the reply.

If I understand this correctly then, the torque converter won't convert torque for 30 seconds or so, while it fills with fluid, but (owing to the shape of the torque converter) there will be enough fluid to maintain lubrication. As long as I let it run in neutral during that refilling process, it's okay.



Other than the check valve, what is the preferred "fix" for the TC?

 

[cerberusiam]

The TC will never completely empty so no problem with lubrication. When the fluid starts circulating the fluid path form the pump thru the TC will charge it full again. In neutral usually 30 seconds will sufficiently charge the TC to where it own't slip.

From the factory the TC does not charge in park. Stupid design that has never chnaged in some 30 years th\tta is supposed to be addressed by drain back valves. The easiest fix is a manual valve from Sonnax that allows the TC to charge in park. Most shift kits also address this issue in varying ways.

Everythng I modify gets loses the drain back valves to get rid of the garbage trap and enhance the cooler flow. Once you add a shift kit and remove the restrictions the OE cooling systems on the 2nd and 3rd gen trucks work quite well.

 

[JR]

I also removed the check valve in my line a few years ago when I had my trans rebuilt. I generally watch the oil pressure gauge come up, give it about 5 extra seconds and it's good to go. That's in warm weather of course. In cold weather I will give the truck more time to warm up. For whatever reason my trans will prime itself when in park. If I start the truck and throw it in gear right away (which I don't do) it's obvious that the tc is not charged. But by simply letting it idle in park for 10 to 15 seconds, when I put it into gear it engages firmly and everything is fine.

 

[abranz]

Remove the ball and spring from the trans line. Yrs ago I had a transmission rebuilder tell me to but I didn't. When it malfunctioned the fluid circut was blocked. Resulted in a total loss of the transmission. No hard parts including the case could be reused and it was expensive.