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Equipment Hub: Don’t ignore that fluid leak

Andy Overbay for Progressive Forage Published on 01 March 2020

Oh no, there’s a pool of something under my tractor. What could it be? Where could it be coming from? Maybe it isn’t too serious – it may have already stopped.

No one likes to find a fluid leak on any piece of machinery, but it doesn’t have to be the end of the world if you handle the situation properly. There are some circumstances where fluid under the machine is not a leak; I have one tractor with a front-wheel drive shield that can catch the last few ounces of oil when changing the motor oil. However, most pools mean there’s a leak somewhere on the machine, and the possibility that it will “heal” is wishful thinking.

Fluid leaks are not uncommon and are simply a sign of wear-and-tear as a vehicle ages. Leaks can range from the extremely dangerous gasoline leak to the type that are more of an inconvenience than an actual danger: windshield wiper fluid leak or normal water coming from the air conditioning drain.

Properly identifying the leaking liquid is key, as some fluid leaks can be dangerous and result in serious damage to the engine or other vital components. In addition, properly identifying the fluid can help you discover small problems before they turn into a major repair bill.

The first step in diagnosing the issue with your machine is to determine exactly what fluid is being lost, but use caution. Exposing yourself to some fluids can be dangerous if the fluid is toxic or has a property to which you might have a reaction.


Let’s look at some of the ways to determine the fluid gathering under your equipment. Coolant losses are generally found near the front of the machine or directly under the radiator or water pump. Coolants can have a neon green, yellow, pink or blue color and will have a light viscosity and a slightly sweet smell.

One thing that may be confusing is: Coolant leaks may occur or appear to be worse when the machine is shut off. One explanation of this is a failed water pump. When the pump fails, a weep hole will leak after the engine stops. While running, the vacuum created by the pump will reduce or even stop the leak, but don’t be deceived. The pump needs to be replaced ASAP.

Motor oil

Motor oil leaks will appear as black, brown or yellowish-brown and have a medium to heavy viscosity to touch. It will also have a slightly acidic smell. Motor oil leaks can be a sign of something as simple as a loose bolt on the oil pan to a serious internal issue such as a blown crankshaft oil seal. Seal leaks will manifest themselves in the front of the motor, which is bad enough, or they can occur in the rear of the motor and affect your clutch and pressure plate assembly.

Hydraulic fluid

Hydraulic fluid leaks can occur anywhere over the length and width of the machine. While similar to motor oil, hydraulic fluids are generally lighter in both color and viscosity. Hydraulic leaks can be easier to see but, because hydraulic fluid can be under extreme pressure, the leak may express itself over a large area.

That pressure can add to the danger of finding a hydraulic leak. Never use your bare hand to feel for a leak. You can sustain serious injuries due to exposure to pressurized fluid.

Because of the pressure and many functions the hydraulics of your machine will perform, it is most likely to be the oily leak that is gathering on your shop or shed floor. Without moving the tractor or implement, begin to trace up from the pool to find that pesky leak.

Even if the leak is under pressure, eventually the fluid will flow down. As the fluid slows, it will gather dust and dirt. As you trace back to the leak source, the machine will generally get cleaner because fresh fluid has “washed” that area off.

Hydraulic leaks usually are the result of a loose or cracked fitting, or a hole in a hose or line. Once you have located the leak, check for either of these issues with the machine off. If you find a loose fitting, simply tighten it, start the tractor and see if the leak is stopped. Be sure to wipe as much excess fluid away so you can more easily see if the leaking continues.

If you find a line or hose damaged, your day may not go as smoothly. Modern equipment can be (actually is very likely to be) a jumbled maze of lines and hoses. The culprit may be located where simply tracing the line from one fitting to the next and replacing the damaged piece isn’t that simple.

I had this issue on one of my tractors that was leaking hydraulic fluid pretty badly. The culprit was a blown power-steering bypass line that returned fluid from the power steering stack back to the top of the transmission housing. The leak was directly under the cab with just enough room to get a combination wrench in to remove the fitting. The other end was nowhere in sight from there.

Raising the hood and removing the side shields, I traced the line as far as I could until it passed through the cab firewall. With the line loose, I pushed the line toward the front of the tractor, circled around to the other side of the engine compartment and found the line that had been displaced.

I marked the line with a bread wrapper and moved it back and forth a couple more times to be sure it was the correct one before removing it completely.

Replacement parts

Another issue in the repair is knowing a little about where to search for the replacement part number. While the leaking line was on top of the transmission, a check of the parts manual showed no such line with the transmission. It was only when I searched the power-steering system did the line appear, and the part was ordered, on the way and installed on the tractor.

Leaks aren’t any fun, but ignoring them will only lead to more serious issues down the road. Get in there, find the cause, and get it fixed.  end mark

Andrew Overbay holds a Ph.D. in ag education and has more than 40 years of hands-on dairy and farming experience.

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