I am going to replumb the transmission lines with all new 3/8 steel tubing, and move the transmission cooler over to the side for direct air flow. Would I still need to run a fan, and if so, can I hook it up to the same relay that runs my electric radiator fan? I know, 3/8" is overkill, but I needed about 3' of tubing and could only buy it in 25' chunk.
You could but I would run a dedicated temp switch for the trans fluid. When it's cool, you need the trans fluid to warm slightly and just because the engine is at a temp that would activate the fan, the trans fluid temp can overheat even with a cool engine due to fluid shear in the converter.
a fan is definitely a good idea here. having proper control of the fan is important. you could leave it on all the time but thats not best. as injectedmav said a temp switch would be good idea. location of the temp switch is important. i dont know the best location. if you put it in the outlet line going from the trans to the cooler, it would make sure the fan is on when the fluid is hot, but would not turn it off if their is enough air flow from the motion of the car to cool the fluid. if you put it on the out let side of the cooler then it would turn on when the cooler is not getting enough air flow to cool the the fluid. this would delay the turn on a moment but would be more regulated on when the fan is used. you could put it in the pan, im not sure how well that would work. i think i would try it on the cooler outlet first. also i would put a temp gauge with the sensor in the pan if you dont have one yet
I was going to use the biggest frame-mounted cooler I could find. 12X12 or so. Maybe 12X9. How do you tell if it is "dual pass"?
I have my transmission cooler w/fan mounted at the rear where the stock muffler was mounted. I monitored the heat when first installed and found I didn't need to run the fan. don't know if it's where it's mounted or just the distance the fluid has to travel that cools it...
there really is no set rule to needing one or not as every application would be different. Gears..stall speed.. type of driving..typical ambient temps.. etc.. all have an impact. The biggest problem with not using one at all and relying only on vehicle movement is temp spikes. Although it's likely better to only have temp spikes on ocassion compared to running consistently hot.. it's a basic fact of life that heat wears/kills parts more quickly and makes life tougher for fluid. I run synthetics for everything I own anyways.. but I'd be damned sure to be using it in a vehicle that has an isolated cooler without a dedicated thermostatically controlled fan.
You want the transmission fluid to get operational temperature. Too cold will do a lot of damage. The stacked flat style cooler is far superior than the tube fin type cooler.
Unless you are running a big stall converter and spending a lot of time idling, you don't need a cooler fan unless you bury the cooler completely out of any air flow. Idling a few minutes isn't a problem and it should cool off as soon as you start to move again. It would have to be an extreme case to need a fan in my opinion, I've never run one. SPark
Could someone post a link to a flat-stacked and dual-pass style cooler, just so I know what you are talking about.
the one on the right is usually cooled by ambient air(no fan) and the stacked plate is normally mounted somewhere in front of the radiator so that it gets some airflow from the fan in addition to speed generated air. When I install the coolers on street cars, I usually plumb them into the lines in series with the radiator tank cooler if it is equipped. This maintains trans temp at a more even temperature, warming it earlier during winter months and providing additional heat conversion since some of that heat is transferred to the cooling system as well as the air stream. Another method sometimes preferred to radiator tank coolers in later model cars/trucks are the thermostatic controls that are installed in the cooler itself or the cooler lines. The cooler hydraulic circuit is a parallel flow circuit so only part of the fluid flows through the cooler at any given time and the thermostatic valve bypasses the cooler and returns it to the pan for faster warm up.
