Radiator Coolant Leak Detection And Repair | Mobil™

Difficulty: Moderate Estimated time: 120 minutes

Your engine's radiator performs the essential task of cooling the radiator fluid (or coolant) that keeps your engine running at the proper temperature, and in many cases it also cools the automatic transmission fluid. There are no moving parts in a radiator, but corrosion from both inside and outside eventually takes its toll, resulting in a leak. A green puddle of coolant under your car is usually the first sign of a radiator leak. In most cases, this leak is small enough that you can add coolant until a replacement radiator can be obtained.

Modern radiators typically have aluminum cores (the finned part) and plastic side tanks. When used with today's modern radiator fluids (and with proper preventative maintenance), these modern radiators can last up to 150,000 miles. This was not always the case. The copper core and brass side tank radiator of most older vehicles typically lasts half that long. However, when you consider that newer vehicles have much more complex engine compartments with tight access to radiators, at least it is much easier to replace a radiator on an older vehicle.

Note that the vehicle shown in these photos is an older vehicle without the usual "nest" of hoses and wires, and without a fan shroud. Newer vehicles will present a much more complicated job that can take much longer.

Setup Park your vehicle in a well-lighted area – outside in daylight is best – and let your engine cool down before performing the next steps.

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.

If you have determined that the radiator is the culprit, there are a number of connections to the radiator that you will need to identify – and ensure that you can access – before attempting to remove the radiator. Check for each of the following:

1. Look to see if the radiator has a shroud (duct work) that directs the flow of air through the radiator. This shroud will have to be removed in order to get to the radiator.
2. Find the upper and lower radiator hose connections. You will need to remove these hoses at the point that they attach to the radiator. Can you reach them and their hose clamps?
3. Is the vehicle equipped with electric cooling fans? These fans typically attach to the radiator frame. They may need to be removed before removing the radiator.
4. Is your vehicle equipped with an automatic transmission? If so, there may be cooling lines that attach to the radiator side tank.
5. How is the radiator attached to the vehicle? There are many different mounting methods. The most common are bolts through brackets on the radiator. However, some designs have rubber pads or pins that have separate clamping pieces bolted to the vehicle.

Point of no return #1 If you cannot locate or remove these items, or if you do not have the tools to perform this service, take your vehicle to a reputable shop and have a professional technician handle the job.