A subscriber to my YouTube channel let me know I technically ran my lines to the cooler incorrectly. Since I installed my cooler fittings to the side, the bottom fitting should be the inlet and the upper fitting should be the outlet. I ran the inlet to the top fitting and the outlet to the bottom fitting.
Here's a quote from the B&M Instruction sheet that I missed:
"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."
The directions do say that when mounting sideways, the inlet should be at the bottom and the outlet on the top because supposedly air can get trapped in the cooler. But, the transmission fluid is pressurized by a positive displacement pump so I would think it wouldn't make any difference if the inlet was on the top or bottom in a sideways mounting installation.
I read a post on a forum where a guy said he called B&M and talked with one of their engineers and said it didn't matter which way you mounted it and which was the inlet or outlet.
Here's what the guy said and it makes sense:
"B&M coolers are made by LONG Mfg. which also makes Tru-Cool stacked plate coolers. Per the FAQ at the True-Cool web site, the stacked plate cooler inlet/outlet can be mounted up, down, sideways....makes no difference.
We installed a B&M #70264 cooler and I called B&M about the inlet/oulet mount direction......the B&M engineer said disregard the instructions that came with the cooler and mount however I wanted....up/down/sideways."
This was another comment by the same guy responding to another members post on the same thread:
"That's why I contacted B&M by phone and was told by one of their engineers that the mounting direction did not matter since the tranny fluid is pressurized by a positive displacement pump and any air would quickly be pushed thru the system as soon as the motor was started."
Here's the link to the Tru Cool website FAQ and they do say it can be mounted anyway you want, even upside down.
Frequently Asked Questions | Tru-Cool
I find it interesting how one company, B&M, can say you should absolutely not install the cooler with the fittings pointing down and then another company, Tru Cool, says you can mount it in any fashion you want and also says nothing of how you should run the inlet and outlet if you mount it sideways. And, both companies sell the same exact coolers. NO difference.
I called B&M myself and the person I talked to did specify in a sideways installation, the lower fitting should be the inlet so the cooler can fill from the bottom and push out any trap air.
I talked with a person at the company that sells Tru Cool coolers and after he talked with one of the engineers. They discussed the way I set mine up and feel since I'm running a small cooler and I've experienced temperature drops, the cooler is working properly and any trapped air in the cooler is probably minimal. I drove a 7 mile mountain road for the 3rd time the other day that I've used as a test for this modification, and I again registered around a 20 degrees temperature reduction ( I reached around 195 degrees at the top of the hill). When I first drove the hill without the external cooler, I hit a little over 220 degrees. The next time I drove it with the new external cooler installed, I cracked 200 degrees by the top of the hill.
I scoured many forums and websites and I read some that say you absolutely can't run a stacked plate cooler upside down (worst orientation supposedly) and others that say it's not a big deal if a little air is getting trapped at the top of the cooler, while others say the pressure from the fluid will push any air out. It was interesting to see pictures of vehicles with OEM coolers from the manufacturer and the cooler was installed upside down. Some people who installed aftermarket coolers upside down said they've been running it like that for years and it's working great. And then another guy said he used a thermal reading tool and saw that the upper part of his cooler had a much lower temperature reading meaning the ATF fluid was making it up there due to trapped air because he had the cooler fittings facing downward. Once he flipped it around, the cooler completely filled with fluid and it worked better.
I guess to play it safe, you either want to mount the cooler with both fillings facing up, or to the side, left or right. If to the side, just use the lower fitting as the inlet of the hot fluid and the upper fitting as the outlet for the cooled fluid returning to the transmission.
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