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Discussion Starter #1
I wanted to save others some trouble if you have this package as I do on my 2017 SH AWD. I have been noticing an annoying "clunk" or knock as the transmission shifts from to about 4th or 5th gear AFTER the tranny is warm. I have had it back 3 times as once noticed it is very hard to ignore and live with. Here were the results of the trips in for service for the issue:

- First trip they were unable to duplicate the issue. Likely due to the transmission being cool (I dropped it off and it sat before they were able to attend to the car)
- Second trip I rode with the master tech. He heard it and after research stated this was normal operation for the vehicle.
- Third trip the Service manager notified me it is a known issue with the transmission cooler, NOT the transmission and since there is no harm being caused to the system, Acura does not currently have a fix planned. The only way to eliminate the noise is to remove the cooler.

Since my boat is only 2600lb and no known fix in sight, I'm having the cooler removed. Bummer.
 

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I can't for the life of me understand how a transmission cooler would cause any noise at all, unless it is not mounted correctly to the radiator...It is a passive thing, fluid just flows through it.
 

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AFAIK, even in modern shift-by-wire electronically controlled transmissions, the physical movements involved in shifting are driven by solenoid valves and hydraulic actuators. Anything that alters ATF flow and/or properties of the hydraulic circuit could conceivably alter transmission function. That and the ZF 9-HP is a finicky POS!
 

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Discussion Starter #5
AFAIK, even in modern shift-by-wire electronically controlled transmissions, the physical movements involved in shifting are driven by solenoid valves and hydraulic actuators. Anything that alters ATF flow and/or properties of the hydraulic circuit could conceivably alter transmission function. That and the ZF 9-HP is a finicky POS!
This. Tech said it is the solenoid and that it is how and where it is mounted in the engine bay that is creating the noise. Once warm, it is certainly noticeable and according to the Svc. Mgr, I am the fourth at his dealership with the complaint and the second to have the cooling unit removed.
 

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Thanks for the info. I have a Searay 180 that is about the same weight and just installed an OEM Acura hitch on my 2015. Next step is the trans cooler, but maybe I shouldn't bother.
 

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Im glad I found this thread. I just ordered my ATF Cooler and hitch to be put on. I am going to have to wait before getting the ATF Cooler installed to see what Acura does for a fix. Have you asked if the ATF fluid is where its suppose to be?. Im sure with the addition to the atf cooler and lines the system requires to be topped off.
 

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Discussion Starter #8
Im glad I found this thread. I just ordered my ATF Cooler and hitch to be put on. I am going to have to wait before getting the ATF Cooler installed to see what Acura does for a fix. Have you asked if the ATF fluid is where its suppose to be?. Im sure with the addition to the atf cooler and lines the system requires to be topped off.
First, and the Svc. Mgr. was very clear on this, Acura has NO fix nor is planning on a fix because in their determination the vehicle is functioning as designed. Secondly, The same Mgr. is sure they put the precise amount of fluid in. He said they must as the 9 speed ZF is a closed system (there is no tranny dipstick even) and that adding/adjusting the tranny fluid is a major operation. Or so I am told.

Whether or not to add the cooler is a tough decision. My boat is only 2800lbs (boat motor trailer and 55 gallons of fuel) BUT towing capacity is the total of what you are towing AND any weight in the cabin, so the 3500lb limit could be easily reached for me and at a minimum I would be close to it while towing in Florida heat. No good solutions for me at this point!
 

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Hmmm.. maybe try asking ZF themselves. I have actually been able to call their tech line and talk to an engineer before about atf availability and change intervals. They were pretty nice too.

Sent from my Pixel using Tapatalk
 

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The ZF transmission is constructed with 2 dog clutches, one for 7th gear, and one for 4th gear. The 4th gear dog clutch seems to be the one that is operationally problematical. That's the gear that surges when downshifting, you may have noticed. When downshifting, the transmission computer will automatically rev match the engine to the new gear. It's very noticeable when downshifting to 4th. It seems to overcompensate, probably to protect the dog clutch.

As originally delivered, so many complaints arose, that Honda came up with Service Bulletin 15-054, dated 12/22/2016. Even with this service bulletin installed, the tranny is still very sensitive to shifting to 4th gear.

Hate to say it, but less than smooth shifting, especially into 4th, is par for the course with the ZF 9 speed.

See also:
Honda lurches ahead with pesky 9-speed transmission - Chicago Tribune

ZF's 9-Speed 9HP Transmission Puts Dog Clutches On The Leash (Note: Honda and Chrysler use same ZF 9 speed transmission)

 

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Man those videos are soooo good... I just got a beer and watch through both of them and I don´t even own a 3G MDX.
 

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Discussion Starter #12
Well my issue is NOT smooth upshifts/downshifts. It is the noticeable knock that is heard under acceleration at around 30 MPH. My dad bought an MDX identical to mine without the tranny cooler and his does not do it. Perhaps the clutch has something to do with it, but shifts are smooth both up and down.
 

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I am interested in this. Vic, you say your boat is 2600 lbs. If that doesn't include the trailer, you will be close to 3500 lbs and potentially over with trailer, a tank of gas in the boat, and any supplies which puts you over the 3500 lb rating for the vehicle w/o the ATF cooler. That may void any tranny warranty if you have problems in the future, right?

I am having the tow hitch and cooler installed tomorrow and will pay attention to any clunking. I tow a boat that is probably close to 3200, single axle, and no brakes

I towed with our 2004 mdx and after market ATF cooler without any problems which we just traded in. We will see
 

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Discussion Starter #14
I am interested in this. Vic, you say your boat is 2600 lbs. If that doesn't include the trailer, you will be close to 3500 lbs and potentially over with trailer, a tank of gas in the boat, and any supplies which puts you over the 3500 lb rating for the vehicle w/o the ATF cooler. That may void any tranny warranty if you have problems in the future, right?

I am having the tow hitch and cooler installed tomorrow and will pay attention to any clunking. I tow a boat that is probably close to 3200, single axle, and no brakes

I towed with our 2004 mdx and after market ATF cooler without any problems which we just traded in. We will see
Boat, motor trailer and 55 gallons of gas= 2800lbs for me. That means I am still allowed 700lbs of people and gear in the cabin to be at or under the limit (some people don't understand that towing capacity equals what you are towing AND what is in the cabin). What I didn't want is to be at or near the limit towing in Florida summer heat. At this point, I'm considering just leaving the cooler on and hoping the come out with a fix. Had I known this I would not have purchased the MDX.
 

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At least there aren't a lot of mountains to tow over in FL. I agree heat is a concern, but there is the theoretical option of slowing down and avoiding full-power acceleration when you're towing. On flat terrain, most of your engine and transmission load will come from air resistance. I know, boring and practical, but sometimes ya gotta do what ya gotta do. Beats driving a Tahoe. ?

As for the loud shift with the cooler installed, as far as we know it's just an annoying noise, right?
 

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Discussion Starter #16
Correct. I am told it is doing no harm to the transmission which is why there is no planned correction for it at this time. The Regional Service Specialist is coming to spend time with the vehicle this Tuesday, so I may know more. To their credit, they seem to be interested in the issue. Like I said, 4 owners with the complaint at my dealership alone.
 

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I am having the exact same issue with the dealer installed 5000lb tow package on 2016 MDX
The shop manager's explanation was similar. Something to do with the transmission itself with no fix, the transmission cooler just somehow amplifies the noise but does not harm the transmission.

It is quite annoying, and I'm really hoping for a solution.
 

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vic bastige - I'm having what I believe to be the same issue with my 2017 MDX. The dealer had my car for almost two weeks and told me it's normal. The kicker is when they took me on a test drive with another MDX, without the cooler, and they said it made the same noise. It definitely didn't make the same noise. I was actually somewhat laughing to myself because the real answer is they simply didn't know what the problem was.

I posted a video on youtube titled "2017 Acura MDX Transmission Popping Noise" showing the sound. I would love to link it here but this forum requires 20 posts to do so (I'm a new member and joined because I find this issue so annoying). Can you verify if this noise in my video is the same one you had? Your description sounds identical...30mph, clunk.
 
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