ATF cooler orientation

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Jan 27, 2011
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Before changing the ATF on the Maxima, I'm thinking of installing a transmission fluid cooler. The best place to mount it seems to be in front of the AC radiator using brackets I'll painfully be making. I'm leaning towards using one of the Haydens: 401, 402, 403, 676 or 678. The Maxima is cramped. Now the first question: would mounting the radiator with the barbs pointing towards the ground result in air pockets inside the radiator? All the photos I've found show the filter mounted with the barbs to the side. Mounting it with the barbs downwards would make for shorter hoses. Second/third questions: do you think the 678 is too big for this application? Are the 676 and 401 too small? A long, narrow radiator (401, 402) installed behind the grille would maximize airflow, while a 678 would be halfway hidden behind the bumper (with somewhat reduced airflow in my mind). I don't have a tow hitch on this car and I will most likely keep it this way. It will be used for commuting in rush hour traffic, trips to the mountains (12-24 per year) from sea level to 6k-10k ft. Thanks for reading.
 
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Freestanding OE (exclusive of integral radiator) ATF coolers typically have their fittings oriented downward in my experience. Didn't review your entire Hayden listing but stacked plate heat exchangers are almost always more effective than tube+fin at dissipating per given surface area. Enjoy your trips to the mountains!
 

zorobabel

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Thanks splinter! I forgot to add that I'll be mounting the cooler in series after the factory ATF/water exchanger. The Hayden models I mentioned have no thermostat.
 
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Yeah so you definitely want a stacked plate cooler. Rule of thumb is to generally fit the biggest cooler you can. Of course if you have tons of room you wouldn't get something the size of a engine radiator. Judging by the limited amount of room you say you have i would get the biggest that fits good. I wouldn't concern myself with any type of thermostat setup. You want to mount it either with the hose barbs facing sideways or up but not down. I know its easier to mount them facing down but its the price you have to pay. You are probably going to mount it sideways so make sure that the hose from the radiator cooler goes into the bottom hose barb and the line to the transmission comes out the top. If its the other way around the fluid just runs through it and does not fill the whole cooler properly. My ford ranger has the oem external cooler mounted with the barbs facing down but i still would not do it this way. A external trans cooler is one of the best things you can do for your trans. Then you only have to worry about it eventually wearing out and not failing prematurely from heat.
 
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Clearly some well-founded cooler orientation debate. I do like the series flow circuitry as it help to speed warm-up of the hydraulic fluid. Bypassing the radiator’s integral cooler is advisable imho only when an internal breach has occurred or as a stopgap measure. Generic OE GM truck (w/ tow package) cooler installation for reference:
 

zorobabel

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Thanks for the replies guys, you helped a lot! I found a good deal ($35.99) and picked up the 678 model (stacked plate type) at O'Reilly. I'm leaning towards mounting it with the barbs to the side at this point. I'm still intrigued by the truck makers mounting the OEM coolers barbs down. Maybe they vacuum bleed the coolers? Regarding the outlet and inlet, outlet at the top makes sense to me. The Corolla has the heat exchanger in the radiator with the inlet at the top, although that heat exchanger might be just a tube. Somewhat off topic, I want to mount a remote filter base in front of the AC radiator on the Corolla. The filter mount is Al, do you think it would provide any measurable cooling to the ATF?
 
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There will be some air in the oil for the first minutes before the air is flushed out. Oil mixes with air much better than water. It doesent bother if its up, down or sideways... - Until you whant to remove a hoose of it, then upwards is nice.
 
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zorobabel

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I mounted the cooler and filter, but the fitting to filter base is leaking sligthly. The filter base is Al and is supposed to be 1/2" NPT. The fitting I got is brass 1/2" NPTF. I raised the question of match when I bought the fittings but the person working there was clueless. Teflon tape was applied. I tightened the fittings pretty hard, I'm worried that I might strip the threads if I tighten them any further. How do I fix this? Thanks. P.S. Why can't this forum let us upload photos? I hate linking to photobucket or whatever.
 
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NPTF threads are the same as NPT threads. However, the NPTF thread roots, crests, major and minor diameters are different than NPT threads. This is so there's more of an interference fit with the mating threads. No sealer is required if both threads are NPTF. Some kind of sealer is required for NPT and NPTF joints. It might be this mis-match that is causing your seepage (even though people do this all the time). Instead of using tape, maybe try a Teflon based paste sealer.
 
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I'm running a stacked plate cooler 4454 from tru cool. It's got a internal bypass for cold starts. I bypassed my radiator cooler. With no loads, city driving my temps are about 180. This is on my Tacoma.
 
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I don't recommend bypassing a working factory cooler. Run additional ATF cooler after the radiator. Hose barb orientation is not an issue. If you used blue teflon tape, try red. Use the biggest cooler that fits. Get a temp gauge.
 
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B&M suggests for their Supercooler: "Mount the B&M SuperCooler with the fittings on top or on the sides. It is not recommended to mount the cooler with the fittings pointing down as this may create an air pocket in the cooler resulting in reduced cooling efficiency. When mounting the cooler with the fittings on the right or left side, the lower fitting must be the inlet with the top fitting routing the fluid back to the transmission." http://www.tmar.net/BM-Transmission-cooler-instructions.pdf
 

zorobabel

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Thanks for the help everyone! I bought some overpriced Permatex high temp thread sealant. I let it cure for 66 hours, before starting up the car and everything is OK now, no leaks. Teflon tape sucks. I have e-mailed Hayden about mounting orientation and this was their response: "I have spoken with our engineer about this before. If the air is complete removed from the system the cooler should function in any direction without issue. My personal feelings are to direct the outlets to the side or to the top. This will prevent the cooler from draining into the pan forcing the pump to fill the cooler each time during start up." Here are some photos of the thing. P.S. The photos are from before I fixed the leaks.
 
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