Transmission and Radiator fluid mixing?

Truck: 2004 V6 auto double cab 43,627 miles

Problem: I think the transmission and radiator fluid are mixing.

Symptoms:Red color in radiator overfill reservoir.

Have needed to add radiator fluid every week or so recently.

Transmission dipstick reading a few inches over the High mark when engine is dead cold.

Transmission fluid is not milky, but seems to be less viscous than normal.



So I know the radiator has a section which also cools the transmission fluid. Could there be an internal breach which is causing the fluids to mix? Is there anyway to confirm this besides the symptoms listed above? The water pump doesn't appear to be leaking at all. Just got back from a 250 mile trip, it ran and shifted fine.

Any help or suggestions are greatly appreciated.

 

It's not uncommon for a radiator to crack between the transmission cooling section and regular coolant. Sounds like the typical symptoms, so I would say a new radiator or repair is needed. But I'm not an expert on them.

 

Thanks for the reply. I'm looking at new radiators on rockauto right now. They have 13 different radiators listed for this vehicle. Does anybody have any input on any brands/types I should avoid or consider?

 

Well, if factory radiator fluid was filled in the truck, it's already a redish color to begin with.

 

No expert on rads either but I have repaired hundreds of automatics that were damaged from the two fluids mixing . Rad coolant removes the bonding material on your clutch packs deystroying the transmission and it happens very quickly .

Have it checked soon . You may be able to catch it by flushing the transmission a couple times . Dont wait until its too late $$$$$$$$$$$

 

It could be that there is red radiator fluid in there. Didnt think about that. I could drain the radiator and add fresh coolant than observe, but it still doesnt explain the excess fluid in the trans. Thanks for the reply.

 

If there's one with a good lifetime warranty, I would get it.

This is true. OP, what color coolant did you have before you noticed the red?

 

Are you checking the transmission with the engine running at warm temp ?
If you had anti-freeze in your transmission , the trans would all ready be shifting like mush and starting to slip . The fluid on the dipstick will look like strawberry milkshake .
Has anyone done anything to the trans ?

 

This is true but if it's blowing out the overflow tank, you keep adding coolant, and the transmission level is high I bet the radiator is junk. VERY common problem on 96-02 4Runners but I've never heard of it happening on a Tacoma. I would stop driving it NOW if you can. This happened on our old 2000 4Runner at around 220k miles. My wife noticed it had puked red out of the overflow tank 10 miles away at work and I told her to drive it straight home. I disconnected the trans cooler lines from the radiator, put them in a 5 gallon bucket, drained the transmission pan, refilled the trans, and started it. When I saw the fluid stop coming out the cooler lines I shut it off and refilled it again. I put 4 gallons of ATF through it this way. Then I drained the pan, pulled it, replaced the filter, and refilled it again and then connected the two trans cooler lines together. Then I drained the coolant and refilled it with water and about a 1/2 gallon of simple green. Ran it up to temp and drained it again. I repeated that process twice with the simple green and about 3 more times with straight water. Then I pulled the old radiator out, installed a new one, filled it with the proper 50/50 distilled water and coolant mix and topped off the ATF. While in the process of fixing this we bought her a lightly used Venza and sold the 4Runner after it was fixed. My brother in law bought it and 10k miles later now it's still going strong. But I have heard of this problem destroying transmissions if you don't fix it soon enough.

 

No, the engine was not warm when checking the trans fluid. I noticed there are "hot" and "cold" zones on the dipstick. It was checked in my cold garage, with cold engine. Once again, the reading was a inch or two above the "hot" zone.

Fluid does not look milky at all.

 

thanks for the reply. The fluid is not blowing out the radiator reservoir. I keep having to add to the reservoir. But I was in a traffic jam a few days ago and sat in one place idling for 20 minutes.

 

Find a nearby garage that has a cooling system pressure tester. Have them disconect the transmission lines and then put the system under pressure. If there is a leak antifreeze will come out of the tranny cooler section. If this happens replace the radiator and take truck to tranny shop and have the tranny flushed and maybe you will be ok

 

Add to the rad not the bottle

 

Adding a transmission cooler is another option bypassing your rad completely . Not recomended to this in cold climates mind you because when warming your engine , the transmission also gets warmed up . Same goes for cooling . proper operating temps of the trans should be about 165-190 f .

 

I've heard of 4Runners completely destroying the clutch packs in the transmission in under 1000 miles from this problem. Thankfully the transmission is creating more pressure than the cooling system so the atf gets into the cooling system more than vise versa. But if you've been driving it this way for a few hundred miles already you ARE on borrowed time if this is what is wrong with the truck. If you are unable to diagnose it and repair it yourself get it to someone who can immediately. This is not something you can wait to fix later when you have the time/funds to do so. Unless you have another car to drive in the meantime...

 

Had this happen to me with an 06' Nissan Xtera. Nissan would not put out a recall but it was (is) a major problem for them with a part on the intercooler line. When you have the leak it's called "intermix" and like said above if the pan is dropped it will look like a pink milkshake. When I started having issues with the trans I took it to a shop and had the pan dropped and of course "pink milkshake". Shop said once rad fluid is in trans it's pretty much a matter of time before you will have major issues with the trans even with radiator replacement and trans flushes. This is how I ended up in my Tacoma

 

X2....hope that rad fluid in not in the trans! Do not drive it and get the rad/inter cooler lines fixed! X2 on the clutch packs being destroyed if rad fluid gets into the trans. Fingers crossed for you!