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Discussion Starter · #1 · (Edited)
Edit: After @Daltongang pointing out that my Tru-Cool 40K might be too big for the application, and after reading @mattthemuppet 's thread, I have switched gears and ordered a Hayden Auto 678 tranny cooler off Amazon... should still be better than the OEM cooler but much cheaper, smaller (and easier to install) than the Tru-Cool 40K. I also drop shipped from the local dealership the hard lines that route through the frame, to make installation easier

I need a transmission cooler on short notice, so I just drop shipped a Tru-Cool 40k from Amazon and will be installing it as soon as it gets here in a couple days.
I know it's a big cooler but it's what was readily available with Prime. I will post pictures on here of how I end up mounting it.

If anyone has already done this and cares to share any pearls of wisdom, they will be greatly appreciated. I already know it looks like I'll have to fab up some mounting brackets to make use of the bolt holes on the center support. Does anyone happen to know the thread pitch of those threaded holes?

I was also trying to get right angle barbed fittings for the cooler to make hose routing easier, but I couldn't find any documentation on the thread pitch and barb sizes needed so I guess I'll have to wait until I have it in hand, and then hopefully can find what I need at a local store.
 

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mines on here somewhere, I used a medium sized cooler and both the center support and the bottom right (looking at the front of the car) radiator support. Pretty sure the bolt holes in the center support are M6 thread. I'll post more later when I have time
 

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found it

the OEM hose kit will make your life much easier, or if you can find some similar hard lines to route the hoses through the holes in the side of the rad support. I also used some 3/4" split loom that someone on here recommended to protect the hoses.
 

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Discussion Starter · #4 ·
found it

the OEM hose kit will make your life much easier, or if you can find some similar hard lines to route the hoses through the holes in the side of the rad support. I also used some 3/4" split loom that someone on here recommended to protect the hoses.
Thank you for all the information. If I could get the complete cooler kit locally on my short time frame then I probably would, but it is such a pitifully small cooler for the expense! I will see if I can at least procure the hard lines like you suggested.
 

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2020 Honda Passport Touring AWD Metallic Steel
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Thank you for all the information. If I could get the complete cooler kit locally on my short time frame then I probably would, but it is such a pitifully small cooler for the expense! I will see if I can at least procure the hard lines like you suggested.
Just make sure to watch the cooling temp gage. With a larger AFT cooler if it is mounted as shown on the on the Tru Cool website, you are restricting air flow to the radiator.

152284
 

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Discussion Starter · #7 ·
found it

the OEM hose kit will make your life much easier, or if you can find some similar hard lines to route the hoses through the holes in the side of the rad support. I also used some 3/4" split loom that someone on here recommended to protect the hoses.
I was able to get the hard lines ordered locally for delivery tomorrow, cost was only slightly more than what I would have paid online including shipping, so it wasn't too bad.
 

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That is an excellent point, thank you for that
The other thing to keep in mind is your location. It's not in your profile. If you live in Texas or AZ then no problem. If you live in Alaska, Minnesota, North Dakota type locations then too big a cooler may never let your transmission get up too and maintain the proper ATF operating temperature. That could also cause transmission issues.
 

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Discussion Starter · #10 ·
The other thing to keep in mind is your location. It's not in your profile. If you live in Texas or AZ then no problem. If you live in Alaska, Minnesota, North Dakota type locations then too big a cooler may never let your transmission get up too and maintain the proper ATF operating temperature. That could also cause transmission issues.
I'm in southeast Virginia, it's 100 degrees with humidity here right now. It's looking like I'm going to push the trip to next weekend though, so I might purchase a slightly smaller cooler to alleviate some of these concerns you're bringing up. Perhaps I should go with the one @mattthemuppet went with.
 

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I think that one strikes a good middle ground and it's pretty cheap. Mine is mounted fairly low and is partially behind the large crash bar, but should get plenty of air. Couldn't tell you the difference it made as I didn't measure before and after transmission temps, but I'm happy it's on there.
 

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Discussion Starter · #12 ·
I think that one strikes a good middle ground and it's pretty cheap. Mine is mounted fairly low and is partially behind the large crash bar, but should get plenty of air. Couldn't tell you the difference it made as I didn't measure before and after transmission temps, but I'm happy it's on there.
Yeah I was going to buy the same exact model you did, but when I searched on Amazon, this one was only a dollar more and they advertized it as being good for towing up to 5k lbs, so I figured it was worth stepping it up slightly.
 

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I'm thinking you can't have a cooler too big. It's easy to decrease cooling efficiency when not needed in cold weather but somewhat difficult to replace a "too small" cooler with a larger one. When I installed the Tru-Cool 4921 (138" sq vs 104" sq for the Hayden 678) I observed zero, zip, nada ECT increase (monitored). I doubt even the larger Tru-Cool unit (187"sq) would affect actual ECT. A T-stat can be mounted in either unit......I use a simple blankie.
 

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Discussion Starter · #15 ·
I'm thinking you can't have a cooler too big. It's easy to decrease cooling efficiency when not needed in cold weather but somewhat difficult to replace a "too small" cooler with a larger one. When I installed the Tru-Cool 4921 (138" sq vs 104" sq for the Hayden 678) I observed zero, zip, nada ECT increase (monitored). I doubt even the larger Tru-Cool unit (187"sq) would affect actual ECT. A T-stat can be mounted in either unit......I use a simple blankie.
Well, I've already cancelled the tru-cool order and have the Hayden in hand as of yesterday, so this is the direction I'm going to go for the time being anyways. If the Hayden can't keep up then I will upgrade and throw the Hayden on my Scion, nothing will go to waste.
 

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May I ask what prompted you initially to order the Tru-Cool MAX #4739 (the largest unit at 40k GVW) vs one of the two smaller Tru-Cool MAX units? Thanks.
 

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Discussion Starter · #17 ·
May I ask what prompted you initially to order the Tru-Cool MAX #4739 (the largest unit at 40k GVW) vs one of the two smaller Tru-Cool MAX units? Thanks.
I actually ordered the Tru-Cool LPD47391.

I've been a manual transmission guy my whole life and don't have a lot of experience with automatics, and what little I do know about them comes from a drag-racing context. The Tru Cool 40,000 GVWR is one of the best budget-option coolers available ($131 on Amazon). Without any other guiding principals, and knowing it's the recommended budget option from some pretty experienced torque converter and transmission builders, I figured it was as good of an option as any.

I assumed because the tranny fluid is still looped through the radiator, it would keep it at a minimum temperature. It wasn't until posting here that I became concerned over airflow to the radiator, or over cooling. Given that target transmission temperature is quite a bit lower than engine coolant, I was concerned that if it was over cooling, and I did have to block off the cooler to increase tranny temp, blocking off such a large cooler could quite possibly have a negative impact on the ECT... the Pilot's radiator isn't that big after all, and I don't want to be bothered swapping it for a bigger one.

At that point it made sense to me to backpedal and go with the smaller unit. Not to mention it was significantly cheaper.
 

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The LPD47391, the LPD4739 and the #4739 are one in the same cooler. LPD4739 and #4739 come with a separate external t-stat that mounts in the rubber fluid lines. The t-stat does not mount “internally” like some other brands/coolers utilize.

I don’t think there is a ”oil to water” cooler on a 2018 Pilot……no such animal on a 2017-2021 Gen II Ridgeline, which is virtually identical under the hood to a Gen 3 Pilot.

The Pilot’s radiator is huge for the engine displacement and ultra efficient. I frequently observe CT2 being 100*+ lower than ECT1. Monitoring actual fluid/coolant temps is valuable info to know…….I saw no change in ECT1 after the BATC install vs before the install. I did notice a solid 40* drop in TFT after the Tru-Cool MAX 49211 install.
 

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Discussion Starter · #19 ·
The LPD47391, the LPD4739 and the #4739 are one in the same cooler. LPD4739 and #4739 come with a separate external t-stat that mounts in the rubber fluid lines. The t-stat does not mount “internally” like some other brands/coolers utilize.

I don’t think there is a ”oil to water” cooler on a 2018 Pilot……no such animal on a 2017-2021 Gen II Ridgeline, which is virtually identical under the hood to a Gen 3 Pilot.

The Pilot’s radiator is huge for the engine displacement and ultra efficient. I frequently observe CT2 being 100*+ lower than ECT1. Monitoring actual fluid/coolant temps is valuable info to know…….I saw no change in ECT1 after the BATC install vs before the install. I did notice a solid 40* drop in TFT after the Tru-Cool MAX 49211 install.
I haven't had a chance to look at it in person yet, but I just googled the radiator and it looks like you're right, there's no passthrough. I am shocked, what a horrible design decision from Honda. I'm not personally a fan of the combination water/tranny cooler, but having nothing at all is worse, especially in such a large, heavy vehicle. Particularly when you consider that they're already generating excess transmission heat with their VCM algorithm. At least the Ridgeline doesn't have to deal with that.
 

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Gen 2 Ridgeline’s have VCM…..unless you disable it…..which I have…..and monitor that it stays disabled.👌
 
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