Oil and Fuel Filters for Small Engines

Richard L. Parish  |  11/18/2004 10:04:36 PM

The typical homeowner has several small engines on lawn and garden equipment.
All of the engines are likely to have fuel filters. The larger machines will also have engine oil filters. Hydrostatic lawn and garden tractors will have filters for the hydraulic oil.
One of the most important things you can do to maintain your small engines and tractors is to service the oil and fuel filters as needed.

Fuel Filters
Most small engines have fuel filters. These filters are especially important on lawn and garden equipment because fuel is usually stored in cans when purchased, then later poured into the fuel tank on the machine. The extra storage and transfer steps can introduce dirt into the fuel - especially if the can, spout, funnel or fill opening is dirty.
Any dirt in the fuel can plug carburetor or fuel injector passages and can cause engine wear. Be careful to keep dirt out of the fuel tank when refueling. Check your operator’s manual for the suggested fuel filter change interval. If you know dirt or water has been introduced to the fuel, or if engine performance declines, you should change filters sooner than recommended.
It is easy to replace most fuel filters (Figure 1). In most cases, you just loosen one or two hose clamps, slip the hose(s) off the old filter, slip the new filter in place and replace the clamps. On some small 2-stroke cycle engines (string trimmers, chain saws, etc.) the filter may be inside the fuel tank (Figure 2). New fuel filters are available from dealers and from auto parts stores. In many cases, a generic in-line fuel filter is quite adequate on 4-stroke engines. You might want to consider using a somewhat larger filter than came on the machine to increase filter capacity.

Engine Oil Filters
Larger engines with pressurized lubrication systems such as those on lawn and garden tractors usually have engine oil filters (Figure 3). It is important to change the oil filter when you change engine oil. A great deal of dirt can be retained in the filter and may be introduced to the clean oil if the filter is not replaced when the oil is changed.
Most small-engine oil filters are the spin-on type similar to automotive oil filters. While the oil is drained from the engine, just use an oil filter wrench to spin off the old filter. Be sure you remove the old rubber gasket (it might stick to the engine). Use your finger to smear a little oil on the rubber gasket on the new filter. Spin on the new filter and tighten it lightly; hand tight may be enough. Filters for many small engines are available at auto parts stores as well as dealers. Buy a quality filter; your engine will last longer.

Hydraulic Oil Filters
It is vital that hydraulic oil be kept squeaky clean. Hydraulic systems have close tolerances. The smallest dirt particles can score and damage hydraulic components and lead to expensive repairs. All hydrostatic drive systems incorporate a filter, generally on the low pressure oil return to the reservoir. The filters often look like spin-on engine oil filters but are not the same.
Hydraulic oil filters provide much finer filtration - and usually cost more. This is one place where you don’t want to economize; buy a good hydraulic oil filter recommended for your machine. Some manufacturers recommend replacing the filter on a new machine after only a few hours of use (typically 50 hours). This should remove any particles remaining in the system from manufacturing and assembly. After that, you should follow the recommendations in the operator’s manual regarding filter replacement.
In most cases, you should replace the filter whenever you change the hydraulic oil. Remember that having a good, new filter installed is no substitute for using only clean, high-quality hydraulic oil and keeping any contamination out of the system.

Fluids - fuel, oil, hydraulic oil - are the heart of your lawn and garden equipment. Replacing filters as needed is vital to keeping those fluids clean and thus protecting your engines and transmissions from damage. Be sure to avoid introducing dirt when changing filters; clean the filter area before removal. Make it a habit to keep an extra filter of each type needed on hand. Your engine will repay you with good service and fewer breakdowns.

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