DieselDaze

Hello to all...<br><br>I have a 95 CTD with the Auto Tranny. (See Sig). Anyway, the stock tranny lines go to what, Ive been told, is a &quot;Heat Exchanger&quot;. This is a black cylinder shaped device located under the exhaust manifold. <br>As I understand, inside this exchanger, the tranny fluid runs over tubes filled with the engine oil. The heat from the tranny fluid is suppose to be passed to the engine oil, where it is then moved to the engine oil cooler.<br>I could be mistaken on this, but that is how I heard this thing works.<br><br>Anyway, if my understanding of the &quot;exchanger&quot; is correct, then it would seem to me that it is not very effecient?<br><br>Would I be better off by installing an aftermarket tranny cooler?<br><br>Any ideas, insite, help, and comments are apreciated.<br><br>Thanks<br><br>Rich

Extreme Diesel

The heat exchanger is a very good thing. It does not use engine oil. It transfers heat from the tranny fluid to the engine coolant. Look at the hose routing. It has two tranny lines coming into it, and also two &quot;heater hose&quot; type hoses. It is not fed from the same source as the heater though. The heater gets the hottest coolant from the top of the head, but the exchanger gets the coolest coolant from the water pump, which is fed from the return hose from the radiator. Weather the t-stat is open or not, the exchanger is getting the coolest coolant available in the system and helps a TON when you aren't moving. hth

VinDiesel

Rich,

Extreme D is very correct about the efficiency of the heat exchanger. Since installing my gauges, the warmest I have seen the trans temp is 180 deg. F. That was during the &quot;in town&quot; stop and go pulling about 24,000 lbs. The ambient temp was fairly cool- about 65-68. As soon as I would get up to highway speed, allowing the tranny to go into OD (&amp; lock-up), the temp dropped to about 145 (just 5 deg over the start of the scale on the gauge). Of course, I have the finned aluminum deep pan, which probably helps a little also.

My suggestion would be to install a gauge, watch it, and add an additional cooler if necessary (keeping the heat exchanger).

DieselDaze

Thanks. <br><br>I appeciate the info. Sounds like I'll keep the exchanger and just put on better tranny lines. (Getting rid of those cheap quick connects).<br><br><br>Thanks again.<br><br><br><br>Rich

Krusty

Is this exchanger there to take away heat, or to add it from start up? Why would you need another cooler on the rad?

VinDiesel

Krusty,<br><br>It's definitely there to remove heat, though under no load conditions in cold weather you might get a slight warming effect. Under really heavily loaded conditions, in hot weather, you might be able to achieve further cooling with an additional cooler.