Can a Bad Radiator Cause Transmission Problems?

A radiator is responsible for cooling the engine and other vital parts of the vehicle, including the transmission. It brings us to the question, can the radiator cause transmission problems?

The straightforward answer to this question is yes. A bad radiator may be responsible for your car’s transmission problems.

broken car radiator

This article will examine how radiators can cause transmission problems, how cracked radiators affect the transmission, signs of cracked radiators, and more.

Can A Bad Radiator Cause Transmission Problems?

A bad radiator could cause transmission problems in your car. The transmission system, just like your car’s engine, generates a large amount of heat. This heat increases the temperature of the transmission fluid that circulates through the transmission system.

The ideal or optimal temperature range for the transmission fluid is 175° to 220° degrees. Anything above this could damage parts of the transmission system.

An overheated transmission fluid could cause seal hardening, carbon formation, clutch burnout, and complete transmission failure.

Furthermore, a transmission cooler is employed by the manufacturer as a means to cool down the transmission fluid. The fluid passes through the cooler and comes in contact with ranges of plates or fins. In the cooler, the liquid is cooled and flows back to the transmission.

You can find the transmission cooler inside the radiator of your vehicle. Once something is wrong with the radiator, the transmission cooler is affected directly, and the fluid remains hot. It could cause severe damage to the transmission system. Thus, a defective radiator is responsible for transmission system problems.

How Does A Cracked Radiator Affect The Transmission?

A broken radiator will create an opening resulting in transmission fluid leaking from the radiator. When the coolant leaks, it could get mixed with transmission fluid. Once you have coolant in transmission fluid, it circulates back into the transmission.

Transmission fluids and coolants are entirely different and should not come in contact with each other. Transmission fluid is oil-based, and coolants are water-based. They are made from various components, and both fluids perform different tasks.

In addition, once coolants can get into the transmission because it is water-based, it erodes their metal parts. It will also neutralize essential additives in the transmission fluid.

Furthermore, a busted radiator will let out coolant faster from the radiator. As the coolant leaks, there is no longer enough to create the perfect environment in the cooler to cool the transmission fluid.

When driving with a cracked radiator, you face two transmission-related problems. The first problem is the coolant in the transmission fluid flowing back into the system. And, you have an overheated transmission fluid due to a failed radiator.

Signs of Cracked Radiator

A cracked car radiator comes with different signs which are easy to pinpoint. Some signs of a radiator damageddue to cracks included the following.

1. Coolants leak

You should know that where there are cracks, leaks will be present. Cracks in the radiator will create an opening for coolants to leak out. You will be able to see leaked coolant in exhaust or dropped on the floor.

Coolants are usually yellow, blue, or green to differentiate coolant leaks from other car fluids.

2. Sludge build-up

When you have cracks in the radiator, it will affect the condition of the coolant. The gap allows foreign substances into the coolants. It could weaken the barrier between the coolant and transmission, which will eventually fail. It will get coolant in transmission, causing sludge build-up.

3. Overheating

If you notice that you constantly have an overheated engine, this could mean that you have a cracked or blown radiator. Cracks in the radiator significantly hinder the quantity and quality of coolant that the engine gets.

The cracks leak coolant from the radiator and do not allow enough to get to the engine. It causes the engine and other essential parts of the vehicle to overheat.

4. Low coolants

The cracks in the radiator create a leak that constantly drains the radiator of coolants. It leaves your vehicle with a constant low coolant level.

If you notice that your vehicle consumes a lot of coolant, you must have the radiator checked for cracks and other leaks.

Coolant can last for a long time. The change interval for coolants is usually every 30,000 miles. In some vehicles, the recommended change interval could be 60,000 miles for the first change and then 30,000 miles for subsequent changes.  

5. Triggered check engine light

The check engine light will come on due to the engine’s condition. Due to the engine not receiving enough coolant, heat builds up, which can trigger the check engine light. The heat can also damage parts of the engine which could also keep the check engine light on even when the engine has cooled down.

6. High-temperature gauge

The temperature gauge has the sole purpose of showing the temperature of the coolant. When there is a crack, the engine coolants will most likely have a high temperature because it could be contaminated or insufficient.

A temperature gauge in the vehicle will always read high when there is a crack in the radiator.

7. Rust

Rust is another sign of a cracked radiator. The opening on the radiator allows water to enter other radiator components, causing severe rust. You get this fixed as soon as possible.

Why Is There Transmission Fluid In My Radiator?

Internal cracks majorly cause transmission fluid in the radiator. As we know, the transmission fluid travels true to the radiator entering the transmission cooler to get cool.

A barrier separates the coolants in the radiator from the transmission fluid. Many factors could cause the barrier separating these fluids to crack. Some of these factors include.

1. Faulty thermostat

2. Leaking gasket

3. Low coolant level

4. Design flaw

Once the barrier separating the fluid fails, then there is a problem. Transmission fluid gets into coolants, and it flows through the engine. Also, the mixture of coolant and transmission fluid could escape to the transmission causing problems too.


Once you realize that a radiator is busted and experiencing some coolant in transmission damages, you must immediately fix the problem. Problems like this could seriously damage your engine and the transmission system. Solving the situation when the engine is affected will take a lot more. 

Akindayini Temiloluwa

I am Akindayini Temiloluwa, an automotive expert writer and car enthusiast. I have over three years of experience in the automotive writing niche and have completed over 300 pieces of content from 50 projects. I have vast knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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