My transmission fluid is leaking into my.

Tiny
BABYD37
  • MEMBER
  • 1997 FORD EXPLORER
  • 165,000 MILES
My transmission fluid is leaking into my radiator. I had someone to flush it out and still transmission fluid leaked into my radiator. Do I need a new radiator? What can I do? Also my overdrive light was blinking off and on constantly. Thank you
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Wednesday, April 3rd, 2013 AT 6:28 AM

22 Replies

Tiny
CARADIODOC
  • MECHANIC
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Replace the radiator. The transmission cooler inside it is rusted and leaking. Coolant will go into the transmission too when the engine is stopped and still hot enough to build pressure in the cooling system. The transmission should be flushed too, then address the overdrive problem if it still exists.
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Wednesday, April 3rd, 2013 AT 6:55 AM
Tiny
BABYD37
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Thanks, I purchased a radiator today. Didn't know it was that expensive (lol) and got the coolant and transmission fluid.
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Wednesday, April 3rd, 2013 AT 8:38 PM
Tiny
CARADIODOC
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Normally I don't recommend for or against transmission flushes but in this case it might be a good idea to have that professionally done. You will only get about four quarts out with a filter and fluid change. Another four or five quarts hangs up in the torque converter, clutch packs, and other passages that will only be removed with a flushing machine. Antifreeze doesn't have the lubricating properties of engine oil and transmission fluid but more importantly when antifreeze gets into engine oil it will melt the soft first layer of the engine bearings leading to catastrophic failure. Automatic transmissions have drums that rotate on similar bearings so logic would dictate they could suffer the same fate.

The cooling system is not as critical but you do want to flush the system. Engine oil and transmission fluid will rot the rubber radiator and heater hoses from the inside. They will look fine from the outside but you'll never know when one will pop a leak. I would drain as much as possible then remove one heater hose from the engine and run water from a garden hose into the hose and the port to flush the heater core. That will wash through the engine block too and flush that out. I like to remove the rubber hose for the reservoir from the radiator and let it hang down. Fill the reservoir and force water to run out the hose. It will siphon itself almost empty that way. When you refill the system there is going to be some water left in the engine and heater core that you can't get out so you'll need to put in more antifreeze than water to get a 50/50 mix. After running the engine long enough to warm it up, the coolant will be mixed and you can take a reading for the freeze point. Then you'll know if you need to add more water or more antifreeze, and since the reservoir will still be empty you'll have a place to put it.
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Thursday, April 4th, 2013 AT 2:49 AM
Tiny
BABYD37
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Okay thanks, I had a mechanic to replace the radiator and all the other stuff too. Thanks so much. The truck rides good. Thanks so much
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Thursday, April 4th, 2013 AT 8:38 PM
Tiny
MIDIHEAD
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  • 9 POSTS
  • 2002 FORD EXPLORER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 124,000 MILES
Since July of 2009, my SUV has been leaking transmission fluid from the vent hole while/after driving. I usually drive 40 to 74 miles each day, mountainous driving. It seems like the transmission needs to get hot before it leaks. It does not appear to leak once the transmission has cooled down completely nor does it leak while just sitting parked for several days at a time.

My local Ford garage finally localized the leak to the vent hole after initially thinking it was the transfer case gasket and transmission pan gasket leaking. They so far have been unable to determine why the fluid is coming from the vent hole since they have not yet opened up the transmission. They think that maybe the transmission fluid is possibly overheating and causing the fluid to expand to the point of leaking. They are currently attempting to connect some kind of gauge to the transmission to check pressures while/after driving but they are having difficulty getting the gauge connected due to the tight working space.

I am aware from your site that an internal leak could cause fluid to drain back into the transmission overnight, causing it to overfill and leak from the vent hole while parked overnight, however, my issue occurs while/right after after driving.

My transmission does slip a little every once in a while and sometimes will shudder a little after cresting the top of a hill when in overdrive. It also has occasional harsh engagement when in trying to put it in reverse. The garage has not seen any clutch material or metal chunks in the fluid the last few times they looked at it. Also, once after driving, the transmission would not go into any gear until it cooled down.

Could the solenoid pack cause all of these issues or could there be something more major at work? Could there still be some kind of internal leak that might cause these symptoms during driving as opposed to being parked overnight? Is a replacement transmission in my future?

I have been dealing with this for about five months and really need to get this resolved, hopefully before the snow flies. Thanks for your help!
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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H midihead,

Thank you for the donation.

When trans fluids are overfilled, they would leak from the vent holes when driving. Did this problem occur not long after trans fluid replacement or topping up?

Overfilling would also cause the fluid to churn and foam and this would cause air pockets in the fluid system resulting in fluid overheating and shifting issues.

Symptoms indicates the fluid is overheating and apart from above, check the fluid cooler and its hoses for restriction which would not allow sufficient cooling.

The solenoid packs would not casue the problem unless they are causing the trans to slip and when this occurs, overheating of the fluid would occur over strenous driving as in your case.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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Thanks for the reply. I had a transmission fluid flush done in February of 2009. Did not notice leak and slipping until late July. The garage assures me that, at the last fluid level check, the levels were where they should be.

Would the pressure tests they are going to do help to reveal restriction in the hoses or cooler? I'm not sure what is involved in checking the cooler and hoses for restrictions otherwise.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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No, the pressure test would not reveal any restriction in the cooling circuit. They would only be testing the fluid pressure for each speed that the trans is in to check if they are within specifications.

To check for restrictions, you would have to visually inspect the hoses ( kinks ), pipes ( distorted or bent acutely ) and disconnect the cooler to check/test.

Transmission flush is a no no for most trans. A fluid replacement and/or filter change is all that is required. Is the garage you send the vehicle to a certified Ford dealer? Hope they have used the correct fluid specifications.

Have you tried replacing the fluid again?
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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If the garage has not yet checked the cooler, hoses, and lines, I will make sure they do that next.

The reason I had the flush done is because my garage thought that whoever had the vehicle before me had another garage put the wrong type of fluid in the tranny. They recommended the flush to clear out the old fluid. To my knowledge, I think my vehicle takes Mercon V fluid which is what my garage says they put in.

Just prior to getting the flush done, the vehicle had been dropping out of gear and kicking back in harshly very regularly. After the flush, it stopped doing that and only recently started slipping a bit besides the leaking issue which started in July. My garage did use TransX right after the flush in February to help recondition the seals, etc.

They have added fluid over the last few months as needed due to the leaking and from when they replaced my transfer case gasket and tranny pan gasket but I have not had all of the fluid replaced again since the February flush.

Yes, my garage is a certified Ford dealer.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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If they have been topping up the fluid thinking it is a leakage, I would get suggest rechecking the level to ensure that it is correct.

I don't recommend any trans conditioners or additives as they might not be compatible with trans fluids operations.

Since problem occurred a few months after replacement of the fluids, we should not rule out the possibility of bad fluids and if they have not been replaced since, maybe you can give it a try and check the filter as well.

Before doing above, check the cooler fins for clogging, this would cause inefficient cooling of the fluids. If problem does not occur under normal driving conditions, the most likely fault would be inefficient cooling.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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Service Manager at my dealership installed the gauge and drove the vehicle locally but could not reproduce the shuddering so far. He said the gauge showed nothing unusual. He said that he will try driving it along one of the more strenuous routes I normally take to try to get it to act up.

I asked if they had checked the cooler, hoses, and lines. He said that they hadn't yet. He stated that the gauge attached to my tranny will show temperatures. He said that if the gauge temperature doesn't show signs of overheating, he doesn't see a reason to check the cooler, etc.

Keep in mind that the Service Manager is currently not charging me labor on this continued investigation into my overheating/leaking issue since they previously misdiagnosed it back in August of 2009 by thinking it was the transfer case gasket and tranny pan gasket as the source of the leaks and charged me $700+ for those repairs. He is personally doing the current diagnosis, however, the process is slow since he's the Service Manager and can't work on my vehicle constantly. I'm trying to stay with my local dealer since I feel they need to make it right for not diagnosing it correctly the first time.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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Some weird problems do require extensive testing and diagnostics and since the dealership is taking responsibility and continuing to perform diagnostics, you would have to bear with them for the time being.

It is true that if the temperature does not increase, the cooler should not be the cause so we will have to wait for them to confirm it.

Sit tight. :)
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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Service Manager called and said they drove it over the last few days with the gauge attached in one of the same strenuous areas I drive in. The temperature reading did not show anything out of the ordinary, nor were there any shift problems showing up.

Service Manager said that his recommendation is, if it were his vehicle, to just drive it as it is. He said that he would hate for us to have to put a bunch of money into the transmission if that wasn't really the problem. This is not a very reassuring recommendation.

It appears obvious that they have no idea what is causing the problems based on the tests they've done. The Service Manager gave no indication what should be next steps if we decided to keep pursuing a solution to the problems.

Not sure what to do now. There is obviously a problem and I fear one day this thing is going to let us sit before long.

Your thoughts?
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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When the test drive was performed, did he encounter the fluid over flowing as well?

When was the last time you encountered the problem?
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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I don't believe the Service Manager specifically checked for further leaking. He was mainly focusing on the gauge readings. He did not specifically say he checked again for leaking.

The last time it leaked for me (and would not go into gear until the tranny cooled down) was on November 7th which was the last time I drove it before taking it back to the dealer on November 9th. They have had it for 3 weeks now. The day I last drove it and had the "no gear" problem, it was a warmer day and all 4 family members were in the vehicle.

As long as the vehicle is driven consistently (several days or more in a row), it will leak. If it sits for while, short trips aren't enough to really make it noticeably leak until it is driven longer distances. The leak is slow enough that the dealer had trouble narrowing it down to the vent hole until they did the dye test recently.

I am supposed to get the Explorer back this Monday, November 30th. Seeing that nothing was done to correct the overflowing, occasional shuddering and occasional harsh engagement when putting it in reverse, I am pretty confident it will continue to do these things.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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From the symptoms and conditions of it occurring, I believe it is a temperature related problem and the weather might play an important part in it.

As the weather is getting colder, you might not have any problem for now.

The fluid cooler might be slightly below efficientcy and the weather would be the factor. When it is warmer, overheating of the fluids would occur over longer and strenous drives and when it occurs, you would have the trans failing.

When the weather is cooler, overheating would take a longer time to occur or not occur at all.

Visually check the cooler fins for obstructions such as grasses, leaves and mud. They would reduce the efficiency of the cooler.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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I will visually check the fins the next chance I get.

I just came across a Ford Technical Service Bulletin (00-23-10) that applies to my model and year.

https://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

It involves the cleaning, flushing, and backflushing of the tranny fluid cooling system and an in-line filter that needs changed when tranny overhauls/replacements are done. To my knowledge, I was told that my tranny had been taken out and either repaired or replaced sometime before I bought it used in February of '09. I have no idea if the cooling system was cleaned before I bought it or if the cooling system and in-line filter replacement was part of the transmission flush my dealer did in February.

This sounds like it has the potential to cause inefficient cooling. Is this something I should have my dealer look into?
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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Yes, the bulletin does suggest a possible fault with the fluid cooler you ought to get the dealer to have a look at it.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
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The dealer didn't see any clogging of the fins on the cooler.

They did a flow test on the transmission yesterday. They said that they got about 1.5 quarts in a 25 second period coming out of the transmission and about 1 quart in 25 seconds coming out of the return line on the cooler that goes back to the tranny. The Service Manager said that the norm is to see about 2 quarts in 25 seconds when doing the flow test. He feels there is likely a restriction in the cooler but doesn't necessarily feel that doing a back flush will improve it much since they flushed it during the flow test and the rate didn't change. He is currently checking with some other folks on the Ford Hotline to see if the flow rate seems like the real source of my overheating issue.

Some possible options he is investigating (if the cooler really is the issue):

1. Replace the entire radiator (the tranny cooler is built inside the radiator on my Explorer, I'm told)

2. Add an new external cooler and bypass the old one.

3. Back flush the current cooler and install the filter kit (he's not too sure this will help much).

I'm hoping to hear more from the dealer tomorrow. What do you think of their findings?
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)
Tiny
KHLOW2008
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You had done repairs to the trans previously and when trans fails, there is a possibility of debris clogging the cooler. Those inside the radiator depends on the coolant to cool it and you have an 25 % difference from the standard.

I would pin that down as the cause as the problem occurs ONLY under extreme conditions and 25% is a lot of difference under such circumstances.

Back flushing would not do much because the mesh inside the cooler is rather close knitted and you would not be abe to flush out all the debris or particles clogging it.

External ATF cooler have higher cooling capacities and that would be the better option, unless if your radiator is is bad condition and requires replacement.
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Tuesday, June 4th, 2019 AT 1:43 PM (Merged)

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