Engine/Transmission (1994 - 1998) Heat exchanger ?s

[Wedge]

So I've been doing ton's of work on my '94 and noticed the hose going to the heat exchanger looked all rusty (the crimped part on the hose) so I figured I'd change it. I called two local dodge dealers and was told that part is $150. at one place and $188 at the other. Can I just put in a transmission cooler instead of using the exchanger. What does it do any way? Antifreeze cools the trans fluid??

 

[Wedge]

Here's a pic of the hose:
#ad

 

[HLEschenko]

I read somewheres that the purpose was to warm the transmission oil for shifting purposes in cold climates. Cold oil will take on heat from the warm antifreeze; then on the other hand when the transmission oil gets warmer than the antifreeze that heat is given up and removed through the radiator.

 

[MMcCallie]

I would get rid of it. Get a transmission cooler that is way bigger than you need since heat is what kills automatics. Mount it behind the grill with the radiator. Re-route the coolant lines and be done. To my knowledge, automatic transmission like to see at least 70 degrees. I forget if that's to shift into overdrive, or to lock the torque converter but i lock mine pretty early anyway.

 

[DBohl]

I read somewheres that the purpose was to warm the transmission oil for shifting purposes in cold climates. Cold oil will take on heat from the warm antifreeze; then on the other hand when the transmission oil gets warmer than the antifreeze that heat is given up and removed through the radiator.

By the time your engine warms up enough to heat the transmission fluid , your transmission fluid will already be warm.

 

[JTroiano]

If its not leaking? Just hit it with a wire brush and paint it.



Jon T

 

[JFaughn]

Theres also a check valve in one of those lines to keep more of the system form draining .
You can get a hydrolic shop to make up a line .
I was thinking about getting rid of the exchanger & putting a trans cooler under the bed , do not want to trake heat between the 2 .

 

[Wedge]

Theres also a check valve in one of those lines to keep more of the system form draining .

If I ran just a huge cooler instead would I need to worry about having a check valve?

For now I'll probably put it back together the way it is. It didn't leak before, it just looked rusty and the way things have been going with this truck I figured it was possibly another problem... . I think I bought a lemon!

 

[fortunate1]

You should just eliminate that HX and reconnect the coolant and ATF lines to bypass where the HX used to be. My truck has an extra ATF cooler with an electric fan (for summer stop & go); that works just fine. The hottest temp in the summer is about 150. I also am not thrilled with the idea of 195 degree coolant "cooling" my ATF in a summer traffic jam. That check valve is a potential choke-point to restrict flow; I ditched that too. The ATF will warm up fine in the winter too. It may only get to 100 degrees, but shifting is fine.

This setup has worked great for about 230,000 of the truck's 350,000 miles.

 

[abranz]

Get rid of the one way check valve. It will cost you a trans someday. The ball inside sticks and or becomes clogged resulting in no flow. Happened to me.

Anthony

 

[JFaughn]

If I remember , I think the check ball was to keep the TQ filled , from what I gathered on one of the best known trans guys , they get rid of check ball , but that may be after they make the trans what it should be , like changing the valve body to circulate fluid at a stop .

 

[Wedge]

If I remember , I think the check ball was to keep the TQ filled , from what I gathered on one of the best known trans guys , they get rid of check ball , but that may be after they make the trans what it should be , like changing the valve body to circulate fluid at a stop .

I just talked to my trans builder and he said it was to prevent the tq from draining back from sitting for long periods. So I think I'll make a new hose/line rather than spend $150-188. Thanx for the help!

 

[Moparsean]

Is there a year when this check valve stopped? Would my 97 still use this? if so I too would like to ditch this check valve. I have a cooler with a fan under the bed,but the left the cooler in the rad still hooked to this system. This hose... . if i have it is at the rad right? thanks

 

[hdm48]

don't mean to disrespect your transmission builder, but the valvebody has a valve that will allow/disallow the converter from draining back.

Want to mess with someone? I am an old dragracer and we used to use 2-3 quarts of 30wt engine oil in the automatics (mixes with transmission fluid). Engine oil will lube better than transmission fluid and will not effect cold shifting but will help hot shifting. Plus engine oil will stay stable up to 6oo degrees where as transmission fluid will carbonize (burn) at 250-275 degrees.

try it sometime, you won't notice any difference when cold, but you will when hot.

the heat exchanger? well, as soon as you move the truck 100 feet, it will be warm.

Here's a test for you, if you have a trans temp guage. Put the truck in gear and your foot on the brake. Load it up and watch the temps go crazy. What does this mean? simply put, 95% of all auto trans heat comes from the converter. The sooner the TC locks up, the sooner it will dump the heat via the cooler.

On my old first gen, I went back to what I know works, a very large cooler and disable the stock pre-cooler/heater.

I've hauled trailers of various configurations for over 35 years and I have NEVER lost a transmission due to heat.



Ok, so now that I've gotten that of my chest, dump the line and run a cooler.

 

[Joe G.]

I replaced all my transmission lines with hydraulic hose. No need for high pressure hose because there is very little pressure in the cooler lines. The hose has to be able to deal with hot oil. I use John Deere HyGard hydraulic oil in my transmission. It runs cooler and cleaner. Shifts are better. No sludge in the pan at oil change time so you can go a lot longer between changes. The only problem I had with this oil is that the transmission runs so cool that the PCM would not let it shift to OD. I replaced the temp sensor with a resistor so the PCM reacts as if the transmission was warm all the time. My coolers are the stock set up except for the hoses.

 

[JFaughn]

Joe G. , sounds like a good mod .