I just replaced my radiator and it’s leaking transmission fluid.

I just replaced my radiator today, and now it's leaking transmission fluid. I'm guessing it's coming from the transmission cooling lines, but I'm not sure why. I replaced the lines and that didn't seem to solve the problem. Do I maybe have the lines attached to the wrong points? Like, do the lines cross or does the right side go to the right and the left side go to the left where they come from the engine… I forgot to look at that before I took it off and I'm afraid that might be the problem, so I tried switching it but it seems like it may still be leaking? Otherwise
Experienced mechanics share their insights in answering this question :
Hi there. The transmission cooling lines are very tricky on a Mitsubishi Eclipse. Sometimes cross-threading or not properly tightening the lines can cause them to leak while, in some instances, a rubber o-ring inside the line might be pinched. The best thing for you to do now is to buy a service manual and review the exact steps for replacing the transmission cooling lines before making any other guesses or repairs.

Or, you can have a professional mechanic, such as one from YourMechanic, come to your location to complete an inspection to determine why the transmission fluid is leaking.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

It could be multiple issues, ranging from a hose clamp that was not tightened correctly, the radiator cap is damaged or not correctly installed, a stripped radiator hose or perhaps the mechanic put too much radiator coolant vs. distilled water and the leak is coming from the overflow tank.
If there was a rupture of the internal radiator tank can cause the coolant to mix with and contaminate transmission fluid. The engine coolant can also become polluted by the transmission fluid, as the pressures of either liquid vacillate.
When coolant leaks from the radiator, it can mix with the transmission fluid, which enters through the cooler lines. This creates a colorful mixture referred to as the Strawberry Milkshake of Death (SMOD). This dreaded mixture is toxic and leads to irreversible transmission damage.
Transmission fluid will leak from the heat exchanger into the radiator where it contaminates the engine coolant. The transmission fluid and coolant will contaminate both the transmission and radiator turning fluid and coolant into a strawberry milkshake.
One common cause of the coolant reservoir being full but the radiator low on coolant is a blown head gasket. Combustion gasses from one of the cylinders leaks into the cooling system, and forces coolant from the engine into the reservoir. Once the reservoir fills up, the rest goes overboard through the overflow outlet.
Pinhole leaks are usually caused by internal corrosion that often indicates that the radiator needs to be replaced by a professional plumber. However, you may be able to temporarily stop the leak by applying cold weld epoxy to the leak on the outside of the unit, or by adding a leak sealer solution to the inside of it.
So, if you accidently overfill the transmission with fluid, remove one of the oil cooler lines where it enters the radiator to allow some fluid to drain out. Or, if you have a small hand pump and a long small diameter hose you can pump fluid out of the transmission through the dipstick/fill tube.
Leading Causes of Radiator Leaks

The leading and most common cause is corrosion in the radiator. Radiators, hoses, and hose connections collect sediment and rust that can punch holes in the radiator over time. In a few instances, weak coolant can be the cause of overheating.

Radiator & Cooling System Problems

If your radiator or cooling system is having issues, you will soon find that your transmission (and other parts of your car) are beginning to overheat — and fast.

There are a lot of different issues that can cause coolant to leak into the engine oil. A cracked or blown gasket is the most common cause of this issue. Apart from this, cracks on the oil cooler, leaky gasket heads, damaged engine block can also cause coolant to leak into oil.
If the transmission`s vacuum modulator were faulty, it could be sucking out transmission fluid and dumping it into the carburetor. If that were happening, the fluid would be combusted along with the fuel, and would come out the tailpipe as smoke.
Bleeding the radiator will get rid of the air and restore its proper function. You hear strange noises coming from your radiators. If you notice hissing, bubbling, or banging sounds coming from your radiators, that`s a sign that they need to be bled.
In case the problem is a transmission leak, a simple reseal service, and transmission fluid flush is all you need to fix the problem. However, if your transmission is severely damaged, you`ll probably need a replacement transmission for your car.
If there is oil in your coolant or vice versa, it generally means there is a failure in one or more of your engine`s gaskets or seals. Your engine is designed so that there is one system that controls engine oil to lubricate your vehicle and another that manages coolant to keep your car from overheating.
Grinding noises, transmission leaks, burning smells, noisy idling, and shifting delays are all common symptoms of a clogged filter.
The most common coolant leaks occur in the hoses that connect your engine to your radiator or heater core, or other small hoses running coolant to different equipment on your engine. The best way to stop these leaks is usually to replace the hose as they are inexpensive and easy to get to.
Typically, a radiator leak starts within the cooling fins themselves, along any plastic or welded seam, at the filler neck/spout or at the bottom where the drain petcock can be found.
The three parts that commonly cease working after the radiator goes bad are the thermostat, water pump, and heater core.
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.
Symptoms of a bad transmission fluid temperature sensor:

Check engine light displays in the dash. The torque converter will not operate correctly. Harsh or delayed shifts. The vehicle goes into limp mode.

The first thing you need to do is locate the source of the coolant leak. It might not be coming from the radiator. The best way to confirm the source of the leak is to wash the radiator and hoses with water, and then start the engine and look for new signs of coolant.
To be sure, you`ll need to pinpoint where it`s coming from using your eyes and your nose. Amber, dark brown or even black fluid is probably motor oil, but it could also be brake fluid. Reddish fluid is usually from the transmission, though it could also be power-steering fluid.
Once water is in there, it`s tricky getting it out because as soon as you start the car, the water will be drawn up into the transmission. This can quickly lead to rust buildup, expanding, adhesive loss on the clutch, and dangerous vapors. The longer it`s driven with the contaminated fluid, the more damage it does.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

There is automatic transmission fluid in a manual transmission. Is it okay to leave or do I need manual transmission fluid?
ANSWER : This would depend on what the manufacturer recommends. Many manual transmissions do take automatic transmission fluid. If your transmission has ATF in it, it is very likely that it is supposed to have that in there. If not, it is likely that the transmission would not function properly with the wrong fluid. Many manual transmissions will also take engine oil as a lubricant. The best way to know for sure is to check your owner’s manual or call your local General Motors dealership to inquire.

I have a leak in the coolant system that I have narrowed to I believe is the water inlet tube off of the lower radiator hose.
ANSWER : First off, I would say it would be best to pressure test the cooling system to verify where the coolant is coming from. With the complexity of repairs to the cooling system on this vehicle, it may be worth the time spent to pressure test the system before tackling the replacement. Now then, as far as replacing the o-ring seal on the water pump inlet tube, it should really only require the removal of the bypass hose, lower radiator hose, and the two (or three, depending on manufacturing changes) mounting bolts that hold the inlet tube to the block. I personally would go ahead and replace the tube while I was there, instead of just the o-ring. Granted, this doesn’t mention what it will take to get down to the inlet pipe, but this is all it should take once you have access to it. If this is something that you feel you could use a hand with, consult with a certified mechanic, like those available at YourMechanic.com.

I just replaced my radiator and it’s leaking transmission fluid.
ANSWER : Hi there. The transmission cooling lines are very tricky on a Mitsubishi Eclipse. Sometimes cross-threading or not properly tightening the lines can cause them to leak while, in some instances, a rubber o-ring inside the line might be pinched. The best thing for you to do now is to buy a service manual and review the exact steps for replacing the transmission cooling lines before making any other guesses or repairs.

Or, you can have a professional mechanic, such as one from YourMechanic, come to your location to complete an inspection to determine why the transmission fluid is leaking.

My car is leaking transmission fluid – I can’t diagnose the leak
ANSWER : Based on the NHTSA database covering consumer complaints, as well as government mandated recalls and factory service bulletins, for your specific year, make and model, I do not see evidence of widespread complaints about transmission fluid leaks. Such leaks are, in fact, common in transmissions made by any car company, particularly if the transmission is older than say 10 years. There is a manual shaft seal, oil pan gasket, output shaft seals, case seals, torque converter seal (inaccessible) and so forth all of which are potential leak points on your transmission.

If you want to identify and resolve these leaks, certainly a certified Mechanic from YourMechanic could come out and perform a transmission leak inspection and let you know where the leak points are and what it will cost to resolve them.

My 1993 Ford f-150 is leaking transmission fluid from the rear end of the pan. ive already replaced the gasket as well as the pan
ANSWER : There are two different places it may be leaking if not from a cracked housing at one of the pan bolt holes. The rear tail shaft housing or the shift linkage shaft seal could be leaking. Have the areas cleaned and vehicle run on a lift to isolate where it is coming from.

Transmission fluid leaked while pulling a car out of mud
ANSWER : From the description you’re giving me, I’m not sure. I know many Fords, including my F150, have a circular seal type bell housing inspection cover near the transmission. Fluid pooled in this area generally indicates an engine oil leak from the rear main seal or a transmission leak from the front pump seal. The only way to know for sure is to have your truck’s transmission leak inspected firsthand by a professional. The team at YourMechanic is an excellent option since we make house calls.

1998 mercedes benz c280 transmission fluid leak from top
ANSWER : Hi there. Unfortunately, we are not able to receive pictures or video to pinpoint damage or identify parts for vehicles through this platform. The best way to identify this item is to search online for a detailed schematic of your C280 Mercedes-Benz or contact a local MB specialist mechanic or the dealership service department to determine the parts name and function. You might also want to have a MB specialist mechanic install and inspect your vehicle for further transmission fluid leaks to ensure the repairs are correctly completed.

Leaking top radiator hose? Leaking top radiator hose how to replace a leaking top radiator
ANSWER : If you have not done a job like this before you might want to consider watching a professional from YourMechanic do it for you, especially as the labor time is less than 1.5 hours so it’s pretty economical. The first order of business, of course, is to make sure that the upper hose is actually leaking and you don’t have a different issue such as a crack is the radiator itself where the hose attaches. Also, if that hose is leaking due to a break in aged rubber, the other "old" hoses should be inspected as well. A radiator hose replacement entails removing any plastic shields that prevent access to the hose(s). Then, you have to drain the coolant to a level below the lowest point that you will be working at. The hose clamps are removed and then you have to carefully "debond" the hose from the point it is attached to the tank. Over time, the rubber will bond really tightly to the radiator and you have to break the seal with damaging or severely scratching the radiator "nipple" (the part the hose slides over). Then you slip the new hose on (with clamps already loosely applied), apply the clamps and you are ready to refill. When refilling, you have to open the cooling system bleeder screws (if equipped) to ensure that air does not get trapped. Trapped air could cause the car to overheat as trapped air can block coolant flow.