Transmission oil leaking from radiator - 2001 Hyundai Elantra

PS fluid cannot possibly leak into the engine oil. They are completely separate systems isolated from one another.

The only fluid that can leak into the engine oil is radiator coolant via a crack in the engine block or engine head or via a damaged head gasket.

On cars with automatic transmissions, there is normally also a separate circuit for cooling the transmission fluid built into the radiator. The oil from the transmission is pumped by the transmission through a second heat exchanger inside the radiator.
This is a separate system but if there is a crack in the radiator where the transmission fluid is cooled it is possible for auto transmission fluid to get into the radiator coolant via a crack in the right area. If auto transmission fluid has got into the coolant an inspection of the coolant will show it.

transmission oil gets into the cooling system by a crack in the cooling coil in the radiator tank.When you say new radiator and it is still leaking oil into the radiator then either the radiator is second hand new or the transmission oil pressure is too high. have a transmission pressure checked before you fit an off the shelf still in the original wrapping new radiator. If the radiator is in good condition and not partially blocked it is possible to replace the tank that has the cooling coil in it. It is essential to properly flush out the engine using the correct detergents ensuring that all the systems are opened.. The next option is an air to air cooler for the transmission which is better than the radiator cooler idea.Costs about the same as a brand new radiator.

There is a "loop" inside your radiator for the transmission oil cooler. If the cooler is leaking inside of the radiator, you will have a kind of funky sludge in your engine coolant. For what it costs to disassemble your radiator and replace the transmission oil cooler, you can purchase a new aftermarket radiator with one already in it.

Hello Todd, sitting here thinking about it only 2 things comes to mind. First question is it is an automatic. If so then your transmission oil cooler inside the radiator has a leak which in turn it leaking transmission fluid into the radiator. So if it is the transmission do you see any red gunk in the radiator or the water. Now same process if it is motor oil if it is a manual transmission. These new vehicle have motor oil flowing through the radiator to cool off the motor oil also known as the oil cooler. 9 times out of ten all you have to do is buy a new radiator or remove the metal or rubber lines running to the radiator and splice them together with high pressure hose. Which I recommend power steering return 3/8 hose, tough stuff. Just slide the rubber hose over the tube and clamp it down tight with a hose clamp and give it a whirl. But first I recommend you flushing the radiator. Good luck.

Your radiator needs to be replaced. Chances are you have transmission and oil cooler lines going through them and there are mixing inside the radiator.

Normally if oil or transmission fluid mixes with coolant it will turn milky looking like a milkshake. Your leak must be pretty fresh. from your description that it is coming out of the coolant overflow I am thinking you have a radiator transmission cooler leaking into the cooling system.

You will need a new radiator and possibly all the coolant hoses if they have become soft from the transmission fluid.

In most cases if your getting transmission fluid in the radiator it is cause by a bad transmission cooler that is built into the radiator and the fix is to replace the radiator.

The repair will change in price from where the leak is coming from. If the pan is leaking or the rear seal your looking at $100.00 or less. If the front seal is leaking then around $550.00. The most common leak is the pan gasket. Also if the transmission fluid and filter have not been replaced in the last 30,000 miles and the pan is leaking then I suggest doing this also why the pan is off .

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

IF TRANSMISSION LEAKING WHILE RUNNING LEAKING AT TORQUE CONVERTER SHAFT SEAL OR TRANSMISSION COOLER LINES GOING INTO RADIATOR LEAKING.YOU WILL LOSE MORE FLUID AT COOLER LINE BECAUSE TRANSMISSION UNDER PRESSURE THE OIL PUMP PUMPING IT THROUGH THE RADIATOR YOU WILL LOSE ALL YOUR FLUID QUICKLY IF LEAK COMING FROM COOLER LINES GOING INTO RADIATOR.DONT DRIVE VAN UNTIL FIX BECAUSE FLUID LOST WILL BE TRANSMISSION LOST.

The radiator has a transmission and engine oil cooler lines to it too. One of the oil lines are leaking, if you know which one that's have the battle. I believe the transmission line is on the passenger sides and the oil cooler line is on the drivers side. Look at where the lines connect to the radiator and see if there is signs of the leak. You may need to spray it down with brake cleaner if you not sure if it's a new leak or old leak from the accident. Good luck and hope this helps. And what do you mean by rear case gasket?? You mean the gasket that connects the transmission to the transfer case, or the rear O ring yoke gasket.

That vehicle has the transmission cooler built into the radiator. You may not be leaking oil into the coolant, but transmission fluid, they both make the same mess. Replacing the radiator will probably fix your problem. Let me know if this helped.

oil in a radiator indicates that the transmission oil cooler in the radiator tank has failed and leaking transmission oil into the radiator
there are 2 possible fixes
fix one is a new radiator
fix 2 is to give the radiator oil cooler a miss altogether and opt foe an air cooler mounted in front of the radiator
the advantages here are that the radiator then has a bigger capacity to handle the engine heat as there is no hot transmission oil adding to the engine heat
the second advantage is that the transmission oil is being cooled to ambient temp and not engine temp which makes for longer transmission oil life
the disadvantage is that it cost a bit more than a radiator initially but the long term savings are real
oil to air oil coolers are available from auto transmission shops and quality auto spares shops