Johnson Pump - Flexible impeller pumps and parts

Johnson Pump, a subsidiary of SPX Flow, is a well-established brand in the industry of pumps for liquids. Their experience can be traced back to the 1950s, and this is the reason it is an original equipment manufacturer for many European and Asian brands of boat engines. Volvo Penta, Steyr, Yanmar, Beta Marine, and Vetus are just some of the companies that entrust the cooling of their engines to Johnson Pump.

Johnson Pump offers a wide variety of service parts needed to maintain your pump, depending on the wear. A leisure boat will have less wear than a fish-farm boat that operates in silty waters daily and year-round. For that reason, there are normal maintenance kits, and more specialized repair kits that include cams, shafts, and so on.

By observing the rate of wear on your Johnson Pump components, you will be able to conduct the relevant maintenance or repair operations in order to prevent an engine overheat. Questions like “How often should an impeller be replaced?” cannot be answered simply, without taking into consideration the use of your boat (commercial or leisure). Typically, a Johnson water pump impeller should be replaced every year when the use of your boat is light duty (pleasure boating with low hours). If the use is more intense, or you use your boat in silt and sand, it is advised to be replaced every six months. When it comes to commercial use, the aforementioned periods are shortened to 6 and 3 months, respectively. Further parts are required to be replaced within your maintenance cycle to keep your pump in working condition. A minor kit is needed bi-yearly/annually for pleasure boating (light duty/severe duty), while for commercial boating, it is required yearly/twice a year (heavy duty/severe duty). Lastly, a major kit is required every 4 years/2 years for leisure activity or every two years/yearly for commercial use. A Johnson water pump impeller kit is usually made up of an impeller and its relevant installation(s) gasket(s). A minor repair kit includes all the above, plus snap rings and/or a mechanical seal and a wear plate if needed. Lastly, a major kit includes all the aforementioned parts, plus bearings, a cam, and often a water pump shaft. Of course, all these parts are varied as per the intended pump model to be repaired. Engine overheating is the primary cause of premature engine wear, and any issues with the impeller can result in this.

The recommendations below are applicable for most seawater cooling pumps, including Sherwood, Jabsco, and Johnson pumps. Under the scope of preventive maintenance, to prevent expensive repairs, Johnson Pumps is suggesting the following tips:

Impeller: Check for tears or cracks. Additionally, check for severe vane end abrasion. Replace every year, or as shown in the image below, if any of the criteria are present.

Wear Plate: Examine the pin for wear, flatness, and fatigue.

To preserve pump flow and suction performance, replace during a major pump rebuild or if wear is noticeable.

Cam: Replace during minor or major pump rebuild or if pitting/wear is evident.

Cover: For optimal pump flow and suction performance, replace during a major pump rebuild or if wear is present.

Mechanical Seal: Replace when the pump is leaking or through a small or major rebuild.

Lip Seal: Replace if the pump is leaking or undergoes a major rebuild.

Shaft: Check for wear at the rubber impeller and lip seal.

Replacement of the shaft will be necessary if the lip seal area has grooves or if the impeller end shaft has significant fretting.

Bearing: Check for corrosion, harsh rotation, or grease loss.

Replace the whole shaft and bearing assembly during a major pump rebuild.

Poseidon Marine shares with you three tips to help you install your new impeller and ensure its proper function:

• To make it easier for the impeller to slip into the housing, use a non-petroleum lubricant, such as silicon-based or soapy water.

• Twist the impeller onto the shaft to install it. An impeller should never be forced onto the shaft. For the impeller to prime and operate correctly, it must have unrestricted movement on the shaft.

• When changing the cover, apply a tiny bit of non-petroleum lube to assist in retaining the o-ring in place.

During an extended period of disuse, the impellers' lifespan can be preserved by properly storing them. Poseidon Marine suggests that after removing the impeller from the housing, keep it somewhere cool and dark. By doing this, the following will be avoided:

Copper bonding of the impeller onto the brass housing.

Vanes "setting" into position as stored in the housing

U/V (sunlight) deterioration