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Discussion Starter #1
Well hello again everyone. As seems to be the routine for me, I fix something and then wait a few months for the next thing. That happened yesterday


I was driving (approx 65mph) when I noticed the engine rpms were jumping around, while my speed was rapidly declining. Instinctively I tried getting it moving.Managed to limp off of the interstate and onto a side road. Took a look outside and saw I was losing fluid at a fast rate. Engine off. Saw some type of fluid sprayed all over the engine bay (left side near steering fluid reservoir) which I later concluded must have actually come out of the coolant reservoir, when I discovered that what was once coolant is now some mix of what I assume to be coolant and transmission fluid.

I opted for an immediate flatbed ride home. I’ve resisted the urge to start the car.

This appears to be something quite common with the 2005 MDX. I understand what needs to be done; new radiator. Perhaps a separate cooler. Triple flush of transmission. Etc.

My main point of this post before I spend the time and dollars is, what are the chances that a replacement radiator, a triple flush etc will restore the old beast to fight another day? Is it likely that the transmission is damaged beyond repair? I’m on my second replacement and at $3k a go I’m not about to do it again on a 2005.

Thanks for any input you all have. I’m posting from mobile, so I apologize if any formatting issues occur.
 

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Took a look outside and saw I was losing fluid at a fast rate.
Yikes!

Engine off. Saw some type of fluid sprayed all over the engine bay (left side near steering fluid reservoir) which I later concluded must have actually come out of the coolant reservoir, when I discovered that what was once coolant is now some mix of what I assume to be coolant and transmission fluid. I opted for an immediate flatbed ride home. I’ve resisted the urge to start the car.
Everything in this paragraph constitutes a 100% correct list of decisions.

This appears to be something quite common with the 2005 MDX.
For the second gen too (I had almost identical situation back in 2016 with my 2008 MDX). Not that this is applicable to MDXs only, because it happens to a lot of other brand cars as well, because of how transmission cooling is engineered.

I understand what needs to be done; new radiator.
Correct, and a bunch of new hoses.

Perhaps a separate cooler.
That is if you want to invest in it. I would if I was planning to have the car for the next 10 years. If not, IMHO, not worth investing.

What are the chances that a replacement radiator, a triple flush etc will restore the old beast to fight another day? Is it likely that the transmission is damaged beyond repair?
It depends on whether the coolant got into transmission or not.

I’m on my second replacement and at $3k a go I’m not about to do it again on a 2005.
Replacing a radiator is certainly not a $3K job even at the dealer. I spent CAD $930 tax included at the dealer for a full rehaul (that includes all hoses, clamps and pipes). That's not even USD $700. And that's dealer prices with OEM radiator that is 1/3 of the entire bill itself. You can probably get away with about USD $500 bill with an aftermarket radiator and third party shop.
 

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If I was in your position I would do exactly as you and AcuraAddicted said hoping for the best, if I otherwise wanted to keep my MDX. But I think you need to be prepared that the transmission will die best case within a couple thousand miles.

If the rpms were jumping around, and the car was slowing, and it wasn't registering as overheated, that means almost certainly coolant got into the transmission and was destroying the required lubrication properties of the fluid, friction surfaces of the clutch pack to transmit power, and contaminating seals and solenoids.

No matter how many transmission flushes you do, which can be risky itself, you'll never get all the moisture out.

I'd also see if you can get one of those oil dehydrators like they use on big rigs to continue drying out the ATF fluid as you drive.

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I think the OP is saying he/she doesn’t want to spend another $3K on a trans if chances are not good that it survived.

Depending on the rest of the X’s condition, it might be worth a try. If you DIY, it might cost you $300? to see if it can be saved. First you could drain the trans to try and gage how much coolant got into it. Prob around $120? for doing the 4x drain and refill with a lower cost multi-vehicle fluid from Valvoline or similar. (I would do this soon). Thing is, you have to get it running and in D to circulate the new fluid.

Not sure if you can safely bypass the radiator with the trans lines and how bad the radiator leak is so a replacement rad is prob $150 on rockauto. You could wait on the upper and lower hoses to see if the trans can be saved. If you get that far and your local Walmart stocks it, they sell the blue coolant for about $13/gal. They sell the trans fluid too.

A new rad should outlast the car so don’t think it’s worth a trans cooler to bypass the radiator.

A shop, maybe even a quick oil change shop, could prob do a better job getting the trans fluid exchanged in one pass but have no idea how much that would run - $350, $450? Prob worth a call.

Good luck!
 

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Yes I wouldn't spend the probable cost of a mechanic to attempt a save either. But I would DIY attempt it in stages as you say.

I have my radiator cooler bypassed. But I installed a big external cooler at the same time. It works great even towing in the summer.

Bypassing the radiator cooler like that without an external cooler would only be acceptable in the winter if you drive like a grandma.

Depending on what blew in the radiator you might be able to find plugs you could JB Weld in to plug the internal cooler. But I've thought I've seen radiators for $150, and I would just replace it. Depends on ones interest in saving money and experimenting, vs. saving time. I've gone both routes and sometimes it works out, other times it doesn't.

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Couple more things. If you determine it can be saved but there is trans fluid in the cooling system, then the cooling system should be flushed too. Should take less than 2 gallons.

If you DIY the radiator, you'll see some posts that say the front bumper cover must be removed. I've done the radiator change myself and for sure, the cover does not need to be removed. Here's the post with pictures.

 

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FWIW, I'd do just what most of the others here suggested - replace the radiator, and triple-flush (minimum) the transmission. In fact, I'd probably leave one of the radiator cooling lines disconnected, and pump the transmission fluid out that way. The advantage of this is that you won't be "recycling" the fluid and leaving 30-40% of the old (contaminated) fluid in the transmission after every drain-and-fill. The way this works is that you leave the "output" line in a bucket that's got a line drawn for two quarts. Then start the engine, run it until you get two quarts out (assuming there's enough IN the tranny to do that). Then you pour in two quarts, and repeat the process. In fairly short order (probably 9-10 quarts) you start seeing what looks like really clean, new fluid coming out. Button it up, and make sure you get the proper amount of fluid in the tranny. Drive it for a few days, THEN do another drain-and-fill or two.

And FWIW, I'd put in 10-12 ounces of LubeGard Platinum on the last drain-and-fill. Seems to do good things for Honda trannies, and might help here.

The bottom line is that there's a good chance that you'll end up with a working transmission at the end of this, and avoid the pain of a rebuild / replacement.
 

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+1 for a cooler line "flush" of the trans after a new radiator. Anecdotally I would say you have a decent chance of having not hurt the trans bad enough to wreck it. I know of people who have managed to save the trans that didn't act as quick as you did. You did everything right as soon as you knew you had a problem.
 

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Discussion Starter #9
Rock auto has various (quality) radiators that are all below $110. I think I'm going to try for a DIY fix.

Tomorrow, I intend to do some reconnaissance work; Do some disassembly, remove the radiator, and see what I can do to flush the coolant system - I assume some form of garden hose at some point, and let it run would be sufficient for now.

My concern is any coolant in the transmission; Best case, I get the replacement radiator Thursday this week, and wont be able to install it until next Sunday; Is there anything to be done in the meantime; I can't start the engine, obviously. But I can drain as much transmission fluid as possible tomorrow using the drain plug.

Sincerest thanks to everyone for the responses!
 

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Discussion Starter #10
I think the OP is saying he/she doesn’t want to spend another $3K on a trans if chances are not good that it survived.
Exactly; I should have been clearer.
.....for doing the 4x drain and refill with a lower cost multi-vehicle fluid from Valvoline or similar. (I would do this soon). Thing is, you have to get it running and in D to circulate the new fluid.
Are you saying I could use a lower cost transmission fluid just to get things moving, and see if the transmission is in a working condition? How long would you recommend until I put in the recommended fluid?
Not sure if you can safely bypass the radiator with the trans lines and how bad the radiator leak is so a replacement rad is prob $150 on rockauto. You could wait on the upper and lower hoses to see if the trans can be saved. If you get that far and your local Walmart stocks it, they sell the blue coolant for about $13/gal. They sell the trans fluid too.
I picked up a radiator on rock auto for well under $100. I did not get the cheapest, but went for the most popular. The old radiator is out, and on my next day off, the rebuild will commence.
A new rad should outlast the car so don’t think it’s worth a trans cooler to bypass the radiator.
I'm a stubborn old man. I want to keep this thing running for many many many years to come; With that said, I live in New England, and at some point she'll succum to rust....
Good luck!
Thank you Sir. As I mentioned, everythings torn apart now; Will rebuild on Sunday, weather permitting.

By the way, and ideas on the specifications of all the 10mm bolts? A good 3 or 4 were rusted and I used an extractor....


......In fact, I'd probably leave one of the radiator cooling lines disconnected, and pump the transmission fluid out that way. The advantage of this is that you won't be "recycling" the fluid and leaving 30-40% of the old (contaminated) fluid in the transmission after every drain-and-fill. The way this works is that you leave the "output" line in a bucket that's got a line drawn for two quarts. Then start the engine, run it until you get two quarts out (assuming there's enough IN the tranny to do that). Then you pour in two quarts, and repeat the process. In fairly short order (probably 9-10 quarts) you start seeing what looks like really clean, new fluid coming out. Button it up, and make sure you get the proper amount of fluid in the tranny. Drive it for a few days, THEN do another drain-and-fill or two.
Hello again Habby, glad to hear from you on yet another issue of mine! Do you happen to know or have a diagram showing which of the two lines is the output, and perhaps any more details on the specifics of doing this method?
 

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I've actually done this thinking like some cars I could pump it out with the output line, and draw fresh in from a jug with the return line.

It doesn't work that way in a MDX. But the way Habby describes would work.

The output line is the pipe and hose barb on the transmission case to the front of the car. It connects to the driver side of the radiator. Fluid exits the passenger side of the radiator and goes across the long metal crossover tube, before it goes back into the transmission on the hose barn to the rear of the vehicle on the transmission.

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If you are a visual person search the forum or internet for a PDF from Acura - MDX ATF and power steering coolers installation manual.

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I'm not completely clear about what happened to your vehicle, but I can tell you what happened to mine with a similar and perhaps identical story.

I was driving up the hill to my house and all of a sudden the power to the wheels was dramatically weak. The engine reved, but the car hardly moved. I pulled over and saw a big trail of liquid behind the car. I had it towed to my repair shop.

The transmission oil line goes through the radiator to cool the transmission oil. The port on the radiator where the transmission line connected broke causing the transmission oil emptied out quickly. Since I stopped the vehicle within a few hundred yards of noticing the problem the transmission was not harmed. There was no water in the transmission lines. The radiator had to be replaced. The transmission was flushed to get out all the old oil, which needed be done anyway, but was especially important since the old oil probably got a bit too hot.

The vehicle runs like a top. No problems in the past 30K miles.It cost about $600.
 

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Congrats Sparky on progress. Re the trans fluid, I suggested the lower cost universal fluid (and non Honda brand coolant) so your cost would be minimized if the trans wasn’t able to be saved. There are members here that use the Valvoline trans fluid and say they have no problems. (Hondas have used Dexron and your manual probably states it could be used). If I found a significant amount of coolant in the trans and if it were me, I’d probably change it in the first 1000 miles. That’s just my opinion.

Hey, on flushing the cooling system, it’s best to avoid tap water as the chlorine can attack the alum. Best to use distilled. If you already filled your system, you’ll probably be alright. You could drain and flush again but it’s your call.

Btw, when I flush the coolant, i try to minimize air getting into the system. So I drain about 1/2 the radiator, (start with a cold engine) and then remove the upper hose and use a pvc fitting and some pipe to direct the outflow from the upper hose to a bucket. I then start the engine and after 5-7 mins when the engine warms up, it will start outflowing. When I get about a qt out, I slowly add coolant, not to much as the upper hose is off. Keep doing this until I use about 1.5 gals. Button every back up and use the remaining 1/2 gal to top off when the engine is cold/level over the next couple days.

Would be good to hear how it turns out.

Good luck!
 

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Standalone automatic transmission cooler with a cold weather valve is what I did since I'm in the north east.

Luckily no mixing of trans fluid and coolant happened on the 2005. The transmission cooler line rusted out and popped off.

Had a photobucket account, but they've went private for some reason a while back when I did that fix/improvement.
 

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Discussion Starter #16
Well, today was the day to fix it or let it go to the junk yard.

My old MDX lives to see another day !!!!!!!!

There was plenty of transmission fluid in the cooling system; I flushed it a few times, but it remains, and unless I hear to the contrary from anyone on here, I intend to flush it several times a month until there's little-to-no evidence of transmission fluid.

Likewise, there was some coolant in the transmission fluid; Not much, but enough to notice; I flushed the transmission 3 times, and still have Valvoline MaxLife Multi-Vehicle TF in there, and again, unless I hear to the contrary, I intend to flush it out a couple more times after driving. Once it's mostly clean, I'll likely get the Honda ATF.

The only noticable difference between before and now is that the transmission isn't sure exactly what to do when 'coasting' along at approx 40mph. It moves a couple times between 4th and 5th, and then settles on 5th. I'm aware that this is a known issue, but I've never had it until today.

So yeah, stopping pretty quickly after it all started, and grabbing a flatbed home was likely key to this positive outcome.

Also, when taking it all apart, the transmission pipe connecting to the radiator on the drivers side came off with barely a touch. Completed fell off.

Also note-worthy; the most difficult part of all of this was removing, and then reinstalling the fans!!!! Almost no space to get them out! (Reminds me of the valve adjustments I did earlier in the year - very tight fit!)

I'm about 40 miles off of 222,000 miles, and I'm looking forward to some more time with my car :)
 

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Discussion Starter #17
Oh, also notable was the costs involved. About $80 of transmission for flushing & what's in there now. $40 for coolant (again, enough to flush & what's in there now), and $89 for the new radiator (rockauto TYC 2740). Add in $16 for '4 extra miles' that wasn't covered on my car insurance towing, and we're at $225 plus about 7 hours of my own time.
 

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You got off easy, SparkySteve73! ;-) Congrats - I think you did exactly, precisely the right thing, and your plan is a good one, too. I predict you'll totally get away with it.
 

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Discussion Starter #19
UPDATE: 1 week and approx 500 miles in, and today I completed ATF change number 4 or 5. The outbound fluid was not shiny new red in color, but it was substancially cleaner than ever the most recent change. No water droplets in this change at all. Gear changes are now 100% smooth again, and she's no longer confused choosing between 4 & 5.

I'll do another ATF change in a few days.

The coolant is another story; The temp guage is very steady, but the 'liquid' in the radiator is still milky. I'm guessing this might be a long time to flush through.

Habby, I agree that I have once again been very lucky.

Thanks everyone for your input. And belated happy 4th !!!!
 

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Great to hear you were able to recover!

Re the oil in the cooling system, sounds like you need to try a degreaser. You might google how to remove oil from a cooling system. (I wouldn’t use acid radiator flushes that we’re used in 60s/70s cars with iron blocks and copper radiators to remove rust and corrosion). Some have mentioned detergent but even with the fluid pressure, I would be concerned about foam and forming hot spots. I saw that Autozone carries Blue Devil Radiator Flush and Degreaser. Never tried it but might be worth consideration.

Remember to run your heater on high to flush the heater cores - drive or increase RPMs to get the fluid moving through the cores.
 
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