USALLY it's because the Transmission cooler that's located inside the RADIATOR HAS DEVELOPED A LEAK.The COOLING system & TRANSMISSION need 2 b FLUSHED after the RADIATOR is REPLACED -- OR BYPASS the RADIATOR TRANS cooler & put on an EXTERNAL cooler INFRONT of the existing Radiator.
It sounds like the head gasket is leaking.
I just had the same problem. It started with noticing just a thin layer of light brown foam when I removed the radiator cap. There was no foam or anything else wrong with the engine oil or trans fluid. My mechanic took a quick look at it and said to just keep an eye on it. I checked it every week with no change noticed, then sort of forgot about it for a month. When it started to shift a little rougher than usual, I checked the trans fluid again. This time the fluid was a nasty color of rusty brown and very opaque. Apparently it is not that uncommon to get a leak between the radiator coolant and either the engine oil or the trans fluid. Just speaking from my own experience, I believe it is more common to have the engine oil leak (bad head gasket or cracked head) in which case there will be obvious white/brown foam in the engine (on the oil cap) when it is checked. The trans fluid is under higher pressure than the radiator coolant so most of the flow is from the trans to the radiator, but as the system cools down, it can (and does) flow the other way. It just takes a little longer to notice the problem. Since radiator fluid can destroy an automatic transmission and trans fluid can destroy the seals in the radiator system it is very important to figure out what�s going on as quickly as possible...and NOT �just keep an eye on it�....won�t be going back to that shop. My van (a 94 Pontiac Transport) is in the shop now getting a new radiator (has two internal trans coolers inside of the radiator), and when that�s done I�m driving it directly to have all the trans fluid flushed. With any luck, it will start to shift smoother ...if not, it will have been a VERY expensive lesson. Hope this helps.
the cooling tank in the radiator for the transmission is bad
The transmission cooler (possibly part of the radiator) has failed
The transmission cooler (possibly part of the radiator) has failed.
Most Likely you have a leak from the transmission cooling tank on your radiator to the antifreeze portion of the radiator. Jeff
You have a failed radiator. Most vehicles have a trans cooler on the side of the radiator.
From the transmission? No? But antifreeze & transmission fluid can mix. Your transmission uses a small portion of the radiator as a transmission cooler, normally at the very bottom or side. In very rare instances, this cooler can develop a leak and allow transmission fluid and antifreeze to mix together. The only fix is to replace the radiator.
You have a leaking transmission cooler, usually part of the radiator. The transmission fluid is mixing with the antifreeze turning it pink.
This is a fun one. Pop the hood. Okay, now you're facing the engine...you'll see there's a hose to your left coming out of the top of the radiator, look under that hose and you can see the transmission...the dipstick screws right into the transmission...make sure you're checking it with the engine OFF, and also be careful not to burn yourself on that radiator hose, it can get really hot. The dipstick is quite aways down and rather short.
Most transmissions are cooled using separate tubs in your radiator, if this tube develops a leak it could mix with your antifreeze, you need a new radiator...
Failed oil to water cooler ( usually antifreeze from the radiator ) Water entering through a seal, Dipstick, axle seal, etc Drove into deep water and it came in through the vent.
check your radiator hoses and change gaskets
in the dipstick tube at the front of the engine, just behind the radiator.