Depending on the car make/year.....
Transmission fluid can be cycled through the radiator. When the internal lines fail, tansmison fluid and anitfreeze mix. The lines cannot handle the pressure of the antifreeze as it turns to steam when the closed system is opened. Voila, coolant loss and tranny fluid loss. Auto tech 101. Find new shop.

 

And, a ruined transmission from the dilution of the coolant.

Usually, though, the transmission pump pressure is higher than the coolant pressure and you just get a mess in the radiator and cooling jacket.

Ask me how I know…

You have to replace the entire radiator, as the transmission fluid cooling coil is soldered in place and is an integral part of the radiator.

 

 

The leak is at the radiator, not the transmission housing.

I would check for a cracked or loose flare nut (it is what screws into the radiator and holds the pipe in place).


If you can wipe transmission fluid off the middle of that side of the radiator, it is the top nut.

If you can’t, check the bottom nut.


Aluminum piping and radiators do not get along with steel nuts.

They will ALWAYS corrode, eventually resulting in joint failure.


Remember, that fluid is under pressure from the transmission pump and it will find any way out of that pipe it can find.

This is why you are losing fluid and don’t see much on the floor - you are losing it while running and the system is under pressure.

When you shut off the motor, the pressure stops.


You didn’t say, but I would guess the vehicle is over ten years old.


This is, theoretically, an easy fix, but do NOT let anyone just crank down on the nut - it will break the radiator boss, requiring a new radiator!

Trying to remove it without a good penetrant oil and/or a torch REQUIRES calibrated fingertips - get a mechanic!

You have to replace the transmission line, which comes as an assembly and will have a new nut on it.


I would NOT take it back to that shop !!!

 

If you can wipe transmission fluid off the middle of that side of the radiator, it is the top nut.

If you can’t, check the bottom nut.

This is why you are losing fluid and don’t see much on the floor - you are losing it while running and the system is under pressure.

When you shut off the motor, the pressure stops.

You didn’t say, but I would guess the vehicle is over ten years old.

Perfect, these are exactly my symptoms.

 

I find it to be all too common for a "service advisor" at a stealership to be more of a salesman than a wrench puller. I'm far from a master mechanic but I have the basics down and can usually identify a reasonable concern from a sales pitch. Too many games.

I took my 4Runner to a Toyota stealership for one of the free oil & filter changes at my last visit. The service advisor stated that when I pulled in the write-up area, it was determined that my front end was out of alignment. He said the stealership could align the front end for $120. I thanked him for the information and I would think about it. On the way home, I stopped at a local tire and auto shop I patronize and when they checked the alignment and they said that if it was in fact out of alignment, it was too insignificant to measure. They said no charge. I asked what a complete alignment costs and they said $90.

 

Perfect, these are exactly my symptoms.

By the way, DO get it fixed sooner, rather than later.

If that is where it is originating, it is GOING to spray all over the motor.

Transmission fluid + hot exhaust manifold = FIRE !


Not fun.



Also, FYI, a mechanic can SMELL (or taste) transmission fluid far faster than he can SEE it.


I am not going to tell you how we used to test anti-freeze in the radiator…

 

A good radiator shop can fix you up and afterwards have the tranny fluid changed a couple times. The torque converter retains a bunch of fluid (and maybe coolant?) during a fluid change so get rid of any ‘residue’. New filter too, that’s a must.

And my experience with some service writers and service managers has been that they were such lousy mechanics they were given a clipboard. I’ve known cops that made sergeant that way.

 

Don’t expect a trained auto tech hourly rate at a dealership to be equal to an independent. Don’t expect the skills of an inde mechanic to equal a dealer tech.

Dealer tech - specialists
Indie tech - like the family doctor

I worked as a mechanic for awhile. It took all the fun out of something I enjoyed.

I’m driving a 2001 4Runner, 2003 Camry and 2013 Venza. Notice they are all Toyotas.

If you are buying a new vehicle you need to consider my advice…

• no turbos, get normally aspirated.
• no CVT transmissions. An eCVT in a hybrid is not bad.
• avoid direct injection (newest fueling design) unless it is Toyota D4s or similar dual systems.
• only buy the electrical options you absolutely need.
• if you own a vehicle with active fuel management (cylinder deactivation) defeat and remove this system imeadiately. Or plan on loosing an engine prematurely.
• defeat auto shut-off systems that stop and restart your car at stoplights.
• get in the habit of at least checking fluid levels. On modern cars they have eliminated dipsticks. So, on your car, look under it for leaks. Don’t buy cheap fluids.
• lifetime transmission fluid lasts till the transmission fails prematurely. Change it out occasionally.

 

Dogpiling on Corndogs list

* NO transmission or engine flushes

My datapoints are few and skewed as one only reads or hears of the bad results of transmission flushes. If the transmission is acting wonky, a flush will only
accelerate the failure and likely the damage will be greater.

My wife has a Hyundai with the V6. We received a notice that engine flushes will void the warranty. On the next oil change I took the vehicle to
my somewhat trusty oil change biz. The kid working that day tried to sell me an oil flush - no. I sent the business owner a copy of the Hyundai notice.
In an earlier visit the kid noted the wife was getting the high end synthetic oil. I immediately said just the normal oil which he told me oh this
can lead to engine problems. I did not tell him I had long time friends/customers in the Ford, Chrysler and Toyota engine groups.

To 50 State: Get your leak fixed. Years ago my sister bought a used car with a warranty - a useless warranty. The cooling fluid leaked into the transmission
and took out the transmission. The warranty wording excluded this type of failure coverage.

 

This reminds me of a Nissan Sentra I bought used some years ago. That dealer offered oil changes and inspections for life as part of the deal. Every time I had my oil changed, I was advised to change the turn signal bulbs because they were not yellow and therefore the car would fail inspection. They were in fact yellow, so I asked why they made this recommendation. The answer was "they aren't yellow enough". Needless to say, I never availed myself of their free state inspection. The car passed inspection all 4 years I owned it.

 

To add slightly to @bulkdataman a transmission flush is OK if done very early, less than 50,000 miles. After that I highly recommend what bulk suggests and I do, which is just to drain and refill what comes out of the tranny. This is a partial fluid change as the trans won’t give it all back. The longer you can let your car sit before you do this, increases the amount of ATF that will come out.

The single best thing you can do to get long life is TO USE FULLY SYNTHETIC MOTOR OIL. I use synthetic ATF and synthetic gear oil in my differentials.

 

@Najataagihe
Dealer techs specialize in the car the dealer sells. Stupidity and unethical shop practices can be found anywhere.

Turbos - are mandatory on a Diesel. Diesel fuel is a lubricant. My comments were directed at gasoline engines.

Now to direct injection - with a normal EFI system, fuel is injected into the intake. The intake is at atmospheric pressure so the fuel pulse doesn’t need to be delivered at high pressure. The fuel charge then washes over the intake valves on its way to the cylinder.

Direct injection comes from the diesel world. Fuel is injected at 9 to 13 times the pressure of the older system, direct into the cars cylinder during the compression stroke. The high injection pressure is necessary to overcome cylinder pressure during compression. The fuel does not wash the intake valve. The cars EGR system meanwhile is flowing pure crap across your intake valves so the engine can burn it a second time.

Direct injection is also causing problems with engine oil dilution because the system pushes fuel past the rings.

Why do they use it. Direct injection cools the cylinder as the fuel atomizes and allows higher compression ratios for better thermal efficiency and an smidge better economy. It’s a lot of stuff for very little gain.

A dual (D4s) system has both. Direct for economy and standard EFI to clean the valves. It’s seamless. However; it’s two systems doing what one more simple one can perform.

 

@Najataagihe

Direct injection comes from the diesel world. Fuel is injected at 9 to 13 times the pressure of the older system, direct into the cars cylinder during the compression stroke. The high injection pressure is necessary to overcome cylinder pressure during compression. The fuel does not wash the intake valve. The cars EGR system meanwhile is flowing pure crap across your intake valves so the engine can burn it a second time.

Direct injection is also causing problems with engine oil dilution because the system pushes fuel past the rings.

What a load of crap.

Somebody actually thought this was a good idea for gasoline motors?

I am surprised it doesn't screw up the ignition timing.


My people, my people... ::shaking head::

 

Find a trustworthy shop and stick with it.

We've been using the same 'independent' Honda shop for over 30 years. Of course- both our vehicles are Honda CRVs. We service our cars by the 'maintenance minder', but of course if we suspect something we take it in.

It is sooo nice to be able to take you car to the shop when you need service and 'know' you can trust what they tell you.

 

What a load of crap.

Somebody actually thought this was a good idea for gasoline motors?

I am surprised it doesn't screw up the ignition timing.


My people, my people... ::shaking head::

Depressing, isn’t it?

BTW - the direct injection systems still require spark plugs and all the associated ignition stuff.

 

I WAS a master certified auto tech (specializing in engine performance and electronics) . Been messing with cars most of my life when not in aerospace.
Maintenance is a very important thing.
But the core of the leaking line could easily be a cracked fitting or line which is in the radiator and some packages also have a stand alone cooler in front of or near the radiator.
And to the EGR reburns the exhaust that is not true. The exhaust gas is introduced during coast/no load condition and is “supposed” to be inert and causes a chemical reaction lowering the oxides of nitrous.
But back to the point if people would take and understand the basics of auto tech it could save consumers billions of $. It’s not that difficult but especially the American consumer is lazy.
The flat rate systems most shops (factory or independent) use breeds cheating.

 

@Sr40ken is straining my post for “mistakes”. Let me be more clear. The EGR is the exhaust gas recirculation system. I tried not to be too technical as it wasn’t important to my point.

There is typically un-burned hydrocarbons in the exhaust, depending on your engine’s state of tune. The important part is the exhaust gas that is “reintroduced” is run through your intake system, valves and engine cylinders a second time on its way to the catalytic converter and the tail pipe.

 

The egr supply hasn’t enough volume to introduce many unburnt hydrocarbons. Again, it job is a chemical reaction to reduce oxides of nitrous not clean the exhaust. It’s created a cleaner combustion at trailing/closed throttle. The egr system is closed under power and mostly at cruise.
That said many modern engines today run clean enough egr isn’t universally used anymore.

 

Back to the OP. Check yelp or someone who does local reviews. For your particular issue i would go to a transmission shop. This won't be a new mystery to them.

 

What’s leaking @50 State ? Red ATF, brownish gear oil or anti-freeze.

 

Red ATF

 

What kind of vehicle?

 

It's a 14-year old Kia truck (that was the last year Kia sold trucks in the US, before switching to crossovers). Low mileage, though. A lot of signs of corrosion underneath. It's fun to drive, so I'm trying to keep it going, now that I'm in TX.


Listed from front to rear: Radiator - Leak - Engine - Tranny - (I've never seen evidence of a leak here) - Transfer Case

 

Priority 1 is to verify the coolant and ATF are not mixing. This can really only happen if the tranny cooler lines fail inside the radiator.

-Is your coolant milky or clear (look in radiator)?
-What does the ATF look like on the dipstick? Clean and red to red brown?

• Remember, a leak is going to travel backwards from airflow as you drive.
• A leak won’t kill anything. It’s running out of a fluid that kills your truck.

I would top off my tranny, transfer case and radiator. Then get under my vehicle with a couple cans of break clean and clean off the old oil. Go for a short drive and return. Where did it get wet.

Depending on rate of leakage, you may choose to live with it.

 

Corndog speaks the truth.

 

ATF looks clean and red, no driveability issues as long as I top it off. The new synthetic ATFs make it hard to read the dipstick, so I just wait until there are the beginnings of driveability symptoms. By then it's low enough to add a full quart. It's leaking fast enough now to add a quart every 200 miles. Does not leak when it's not running. When I say the leak is "fast," that's in relation to miles driven, not time elapsed.


I think I see enough ATF leaking to believe it's not going into the rad. Since the vehicle was new, the coolant mixed a bit with the motor oil. The moil has always white-capped. I should have got that aspect fixed back when it was under warranty, but I was working like crazy then, so I assumed they'd give me the shuck and jive. Besides, I used to have a sporty Olds that held up just fine, more than 100,000 miles of coolant mixing with moil, because I got the fluids changed at recommended intervals. That car was still in great condition mechanically when the unibody rusted out.


I like the brake clean idea. Maybe that's what they did to find a slow leak between the tranny and TC.


They scared me with a lot of crazy talk about axles and powerwashing. The last time a dealership missed the mark so badly it was seriously a rip-off.


That's why I don't trust this current place. Fix the fast leak first, especially if it's the easier leak to fix. Don't dig into the tranny and TC seals when that's the slower leak.

 

Is your antifreeze mixture milky?

 

This truck needs love. Oil and coolant mixing is a sign of head gasket issues. Do the spark plugs look ok. If any have a tan/white crusty look your getting coolant in the cylinder.

If it is leaking that amount of ATF it shouldn’t be that hard to find. Indications from what you are saying lead me to believe the rear transmission seal has failed. I’m not familiar with Kia, but this usually means the transfer case will need to come out (not a bad DIY job) then the tranny seal might be accessible without removing the transmission.

 

Well now I feel better. They're going to replace that rear seal as you suggest.


I think Kia's of that vintage were known for those head gasket issues from the factory.


I haven't checked the anti-freeze as carefully as I should have, but I don't remember it looking really wonky. I've seen worse (and my experience with the Olds has taught me not to panic over mild white-capping, so long as fluids are being changed at recommended intervals).

 

You can run an engine with a head gasket issue, but I would fix it. On a 4 cylinder it’s not too expensive to do. You have to be the judge. I had an old Toyota I ran a couple years before I got inspired and fixed the head gasket. It had over 250,000 miles though.

 

This is ridiculous.

 

The OP's ATF issues were addressed, particularly in posts #4 and #29 .

Mild white stuff on oil filler cap is not impossible to be condensation in certain engines , if that's the only symptom , and no oil showing up in coolant .

IF it actually is head gasket , you're rolling the dice . The engine could outlast the rest of the car , or the engine could grenade tomorrow.

 

The OP's ATF issues were addressed, particularly in posts #4 and #29 .

Come on, this isn't a jeep forum, where the guy who's selling performance brake pads wants to turn it into a sterile Q&A "forum," so as not to dilute his marketing efforts.