ATF Cooler and Filter Install

First, always RTM! !


After three attempts, figure I can share some pointers on my ATF cooler and filter experience.

Attempt 1: Thought it might be a good idea to create some separation and not block airflow to the condenser – wrong. I did not RTM . Burned a drill bit going into the bumper beam…


Attempt 2: This will work but my guts say it just doesn’t seem right or to my liking. Too many kinks/bends in the hose and seems to run longer hoses than necessary.


Attempt 3: Finally wised up and read the page long manual. This looked like a nice place to drill a hole . Highly recommend sleeves to prevent the hose from rubbing against the edges of the hole and protect it overall.

Much cleaner and shorter.




Attempt 4 would be more ideal, that is mounting it directly onto the condenser, sans brackets. I considered it but it looks like a real PITA to separate the condenser and radiator enough to use the pull straps through (I read it is not a good idea to tie all 3 together).



Overall, much happier with the 3rd try. Vertical mounting allows you to run shorter hose via most direct route eliminating ~2ft of hose vs horizontal mount and the oil flow path ‘looks’ much better. My aux cooler is connected AFTER the OE cooler, per B&M instruction. I did not try but I do think if you route to aux cooler FIRST, horizontal mount may run with less hose length and flow better. Spend $7 (10ft, needed 3-4 ft) for PET braded sleeves. Another very important point (to me) is that this setup is fully serviceable. I can access every nut, bolt, and clamp should I need to service something. The bracket was made out of $3 aluminum door sweeps from Wal-Mart (measure, cut, drill, *repeat). Two relief cuts and bend one end to account for the rise.


EDIT: For ATF filter, I decided to go the inline filter route (Magafine). I simply disconnected both ends of the ATF outlet hose (to OE cooler) and cutout the section that equals the length of the filter. I made sure to position the filter body so it flows down and that there's clearance and a location to hang the filter body (zip tie) to something as it will add weight once wet.


Moral of the story, don’t be a Homer (like me) and RTM. I could have avoided some work and saved a drill bit.

Thank you for that, concise and detailed write-up. Please keep us (me) updated on how it performs over time, as this is the thing I am most intersted in. I NEED to get/install one of these things as my mileage continues to pile up and I'm getting increasingly nervous about expensive failures like a transmission.

I like how your final set-up came out, Silentnoise713. I think your installation will provide overall cooler trans temps than how I did mine, but like MarkVII88, I worry about cold weather starts and possibly overcooling the trans fluid. I know some trans have a thermostatic switch that allows flow to the cooler only after the fluid has reached a certain temp but I don't know if ours is one. I am going to do some research on that and I still plan to take some temp readings ASAP.

Please do take some measureable numbers. Btw, how and where do you plan to take the temp readings?



I also had some reservations about cold start and overheating in the begining, which was also a motivating factor for attempt 1 (less cooling). Upon further reading, here’s my implied understanding on some of these concerns.

Concern: Cold weather starts
The B&M cooler is a LPD (low pressure drop) design. Essentially, the orifices inside are small enough that upon cold start, thicker oil and will not pass (not easily) through the pleats. It has a bypass so that cold thicker fluid passes through easily to get warmed by the OE 'cooler' - more on this below. As the fluid heats and gets thinner, it can then pass thru the pleats for additional cooling. I’m not sure if all aux coolers have this measure but I don’t think this is a concern for me.

Concern: Overcooling
What is your threshold for “over” cooling? I’ve come across numbers as low as 150 degrees is OK and these air cooled coolers (mine has a 15K BTU rating) drop ~20 range. I would stay well within the safety net. Also, if one is truly concerned with ‘over’ cooling, why bother adding a cooler in the first place? If the margin is small, perhaps the better route is to replace your coolant.

About that OEM Transmission Oil Cooler…
Perhaps you know more but I now better understand the OE cooler is really not a “cooler”. Its intended function is that of an oil regulator, to help “heat” up the ATF fluid AND to “keep” its operating temp at a consistent level – regulate it, which in “theory” should be the ideal temp, by design, for this trans. Coolant/Radiator efficiency and maintenance plays a factor in how well your ATF functions/lasts. I completely changed out all of my ATF (@ 58K) and flushed my coolant (@80K). Also, every installation guide advises to mount the aux cooler after the OE cooler (we’ll keep calling it that since this term sticks) so figure I will follow suite. The moral of this thread is to read and follow instructions – zing!

Interesting that the OE "regulator" isn't really meant to COOL anything. That certainly explains what I have always seen with my SGII watching trans fluid temps day to day. I have always sort of gone with the assumption that anything under 250 degrees maintained is OK, and in almost three years of watching I have never seen a reading higher than 225 degrees. My temps are probably as high as they are (generally between 175-195 degrees maintained) due to the fact that my coolant has yet to be changed, and the health of my thermostat is highly suspect. That being said none of my numbers have never been high enough to trigger an " oh crap! I better fix that!" response. You are, as always, a font of knowledge Silentnoise.... PS, yes know I just contradicted everything I just said in the above post about "needing" a cooler, you have almost talked me out of it entirely LOL

Info pulled from 2008 Mazda 5 service highlights manual:




I can't find any kind of spec in Mazda's publications as to what the fluid temp should be maintained at but generally engine coolant is kept under 220 degrees. It is the warming function that may be hindered by having the aux cooler after the oem. My setup will most likely keep the trans fluid 10 degrees or more cooler than engine coolant but Silentnoise713's will be more efficient. Now am a I scrambling to change mine over, absolutely not, but I do want to take some fluid temp readings to find out how my set-up performs.

Secondtyme said:

Interesting that the OE "regulator" isn't really meant to COOL anything. That certainly explains what I have always seen with my SGII watching trans fluid temps day to day. I have always sort of gone with the assumption that anything under 250 degrees maintained is OK, and in almost three years of watching I have never seen a reading higher than 225 degrees. My temps are probably as high as they are (generally between 175-195 degrees maintained) due to the fact that my coolant has yet to be changed, and the health of my thermostat is highly suspect. That being said none of my numbers have never been high enough to trigger an " oh crap! I better fix that!" response. You are, as always, a font of knowledge Silentnoise.... PS, yes know I just contradicted everything I just said in the above post about "needing" a cooler, you have almost talked me out of it entirely LOL

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You’ve seen it spike up to 225? That is getting up there in terms of accelerated wear on the fluid. Was the car loaded up and going uphill by chance? For the soccer mom/dad, aux cooler is likely not necessary. Maintenance/upkeep of BOTH ATF and coolant is vital for tranny longevity. Now it makes sense to me how it may be a better (?) alternative to upgrade the OE radiator to a higher spec one (koyo/CS). This in turns provides better/efficient cooling for both engine AND transmission. The best place to read/understand more on transmission is truck forums. Folks there do all sorts of stuff (and endless debates) and they do measure/monitor their trannys daily since they actually tow.

After 30K and checking my ATF (Amsoil flush), my gut says it is wearing faster than I’d like (no scientific evidence, just wiggling my finger in the air and no bar to measure). When I changed my coolant @ 80K, the coolant looked good. I don’t like the fact that we have a Mz3 tranny carrying the weight of the Mz5. Plus, there are times when the car does get loaded up with 6 people + cargo for summer trips. With these things considered, and my nonscientific observations of my ATF after 30K, I decided an aux cooler is appropriate for me. YMMV.

loosenut said:

Info pulled from 2008 Mazda 5 service highlights manual:

I can't find any kind of spec in Mazda's publications as to what the fluid temp should be maintained at but generally engine coolant is kept under 220 degrees. It is the warming function that may be hindered by having the aux cooler after the oem. My setup will most likely keep the trans fluid 10 degrees or more cooler than engine coolant but Silentnoise713's will be more efficient. Now am a I scrambling to change mine over, absolutely not, but I do want to take some fluid temp readings to find out how my set-up performs.

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How/Where do you plan to take your temp readings? I can provide Torque app readings after I have the car settled.

BTW, can you get a flow diagram for coolant? Thanks.

Silentnoise713, I plan on borrowing a scan tool that will communicate with the TCM as I'm positive at this point that Torque can't obtain the actual TFT reading since the TCM is separate from the PCM. I'll try and track down the coolant flow when I have a spare minute. Torque just substitutes ECT for TFT.

Here's engine coolant flow as requested.

Thanks!

So is the coolant going into the ‘OIL COOLER (ATX)’ coming from both ‘CYCLINDER HEAD’ and ‘HEATER’? Essentially it will be ‘pre’ heated (to operating temp) coolant?

loosenut said:

Silentnoise713, I plan on borrowing a scan tool that will communicate with the TCM as I'm positive at this point that Torque can't obtain the actual TFT reading since the TCM is separate from the PCM. I'll try and track down the coolant flow when I have a spare minute. Torque just substitutes ECT for TFT.

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Ah yes. forgot about that. Guess I can’t contribute to “the cause”.

Silentnoise713 said:

Thanks!

So is the coolant going into the ‘OIL COOLER (ATX)’ coming from both ‘CYCLINDER HEAD’ and ‘HEATER’? Essentially it will be ‘pre’ heated (to operating temp) coolant?

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Correct, the ATF cooler is warmed by coolant circulating through the cylinder head/block. It is a closed circuit from the radiator until the thermostat opens to then flow through the radiator as well. Notice that the EGR valve and Throttle body are also fed this coolant to reach operating temperature quicker as well. Engine coolant target temp is 180-190 degrees but the cooling fans don't kick on until north of 200 (most commonly 210 or 220) so this may be why Secondtyme is seeing trans temps that high. I personally very rarely see coolant temps above 200 (205 is the max I think I've seen) since I've been monitoring with Torque. I rarely run A/C but people that do may see slightly cooler ECT temps since the cooling fans would be running more often in stop and go traffic.

I was finally able to borrow a scan tool to take some temp readings. I apoligize in advance if the pics are a little too big. All readings were taken on a 72 degree ambient temp day.

5 minutes after cold start.


10 minutes after start. Lite stop and go traffic.


15 minutes after start, Highway cruise.


25 after start, highway cruise.


10 minutes of idle in gear.

As comparison here is readings taken on a 2008 Mazda 3 with stock AT cooler on an 85 degree day after about 10 minutes of freeway driving taken after the vehicle had come to a stop. First was immediately after stopping, second after idling ten minutes.

I found out the other day that some second gen Mazda 3's came equipped from the factory with an additional external trans cooler. Mazda has it mounted after the plate style filter we all have like Silentnoise, as you can see in the following pictures. The outlet from the plate cooler goes over to the d/s fenderwell where a tube and fin style cooler is mounted behind the fog lamp housing. Cut-outs in the fog lamp housing supply airflow over the cooler. If I were doing my install today I would probably put the additional cooler after the plate style factory cooler just as Silentnoise did. After this winter I may pull the front bumper again to go ahead and change the routing on mine but at least for now I know my cooler is being beneficial, just not as efficient as it could be.

loosenut said:

The outlet from the plate cooler goes over to the d/s fenderwell where a tube and fin style cooler is mounted behind the fog lamp housing. Cut-outs in the fog lamp housing supply airflow over the cooler.

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I wonder why the OE cooler is behind the fog lamp? Ram air!? LOL. Wouldn’t this loose the advantage of radiator fan pulling air when it kicks in? Do you have a part number or diagram of this OE cooler?