Servicing the WDP30 Pump

Using the WDP30 Diaphragm Pump

With a rock channel and the ability to handle solids up to 2.4 inches in diameter, Honda’s WDP30 is built to handle the roughest pumping jobs. Here’s how you can keep your diaphragm pump performing at its best.

Maintenance Schedule

Before each use: Check the oil level and air filter on the engine. Inspect the hoses and strainer for signs of damage.
After each use: Flush the pump chamber.
First month or 20 hours of use: Change the oil and grease the pump connecting rod bearing.
Every 3 months or 50 hours: Clean the air filter and sediment cup. Grease the pump connecting rod bearing and check the gearbox oil.
Every 6 months or 100 hours: Check the spark plug and (if equipped) the spark arrester.
Every year or 300 hours: Replace the air filter and spark plug. Change the gearbox oil. Inspect the pump diaphragm and clappet valve.
Every two years: Inspect the fuel line.

Honda also recommends bringing the pump in for service every year or 300 hours to clean the fuel system and check both valve clearance and idle speed.

Spark Plug

Replace the plug if the electrodes are worn down or the insulator is cracked. The electrode gap should be between 0.028 and 0.031 inches or 0.07 to 0.08 mm.

Gearbox Oil

To check the oil, the pump needs to be cold and sitting on a level surface. Remove the connecting rod cover, which is held on by a pair of bolts and washers. Remove the dipstick/filler cap, wipe it clean, and screw it back into the gearbox. Remove it again to check the level.

Here’s how to change the oil:

1. Run the engine for 10 minutes to warm up the oil. This helps it drain faster.
2. With the engine off, remove the two bolts and washers from the connecting rod cover. Remove the cover.
3. Oil will damage the diaphragm, so have a pan ready to catch the oil before it flows down the side of the pump. Remove the oil filler cap from the top of the gearbox followed by the drain bolt and washer from the base of the box.
4. Once the gearbox is empty, reinstall the drain bolt and washer.
5. Add SAE 80W90 GL5 gear oil until the dipstick reads full. It holds about 0.8 quarts.
6. Reinstall the washer, cap, and connecting rod cover.

Flushing the Pump Chamber

1. Disconnect the inlet and outlet hoses.
2. Roll the right wheel of the pump onto a block so that the suction side of the pump is pointed up.
3. Put the end of a garden hose inside the pump inlet and turn on the water. The water can be shut off and the hose removed once the discharge from the pump outlet is clear.
4. Lift the suction side of the pump up to allow any remaining water to pour out of the pump outlet.

Accessing the Clappet Valves

These valves create one-way flow through the pump during operation. Damage can result in leaks that reduce pump performance.

1. Disconnect the spark plug, turn off the fuel valve and flush the pump chamber.
2. Remove the nuts and washers from the intake and discharge ports.
3. Remove both ports. As you do this, note the valve position. These are directional and will need to be 4. reinstalled on the same side and in the same orientation.
5. Inspect the clappet valves. If they’re worn or damaged, replace them. If the case sealing surface is damaged, a wear plate can be installed.
6. Place the clappet valves on the studs. The valve’s flat side should face the pump housing on the discharge side and the port on the intake side.
7. Reinstall the ports and apply a medium-strength thread locker. Torque the nuts to 20 ft-lbs.

Sediment Cup

This cup collects dirt in the fuel before it reaches the engine.

1. Turn the fuel valve to “Off.”
2. Unscrew the sediment cup, located under the fuel valve. Make sure the O-ring is still inside the base of the carburetor and is in good condition.
3. Empty the cup and clean it with a non-flammable solvent.
4. Reinstall the sediment cup.

Spark Arrester

A spark arrester isn’t included from the factory, but it can be fitted to any WDP30 pump to meet local fire safety requirements.

1. Unbolt the muffler from the engine.
2. Remove the screws holding the protector onto the muffler. Lift the protector off of the muffler.
3. Remove the screw holding the spark arrester inside the tailpipe.
4. Clean off carbon deposits with a wire brush. If the arrester is cracked, replace it.
5. Reassemble in reverse order.

Keep Your Pump Running with Quality OEM Parts

Hondalawnparts.com is an authorized Honda Power Equipment dealer, so we’re able to ship factory parts and accessories to your door whether you live in the U.S. or Canada. Check out our pump accessory page, or use our search engine to find parts for your specific model revision.

The Honda Versattach System

The Honda Versattach System

There’s a lot of lawn equipment that’s great to have on hand, but the jobs they do are limited to a few days or even a few hours per year. Buying a piece of equipment for each task means having more to take care of, and often forces you to sacrifice quality to keep costs down. However, you can get around these problems with Honda’s Versattach System. While lawn multitools are nothing new, Honda’s collection of powerheads and attachments get around the pitfalls of other systems, giving you an affordable way to get Honda reliability for your less frequent landscaping jobs.

SureLock: An Easier Way to Connect Attachments

Other multitools rely solely on knobs to hold the attachment in place, have driveshafts that need to be lined up, or use pins that are hard to push out when switching tools. Honda’s SureLock system avoids these problems, simplifying attachment so you can switch tools easily. Here’s how it works:

1. Loosen the joint knob
2. Turn set pin knob 180 degrees.
3. Line up the arrows on the powerhead and the attachment, and slide the attachment into the powerhead shaft until the arrows meet.
4. Turn the set pin knob. If it clicks, the attachment is seated.
5. Tighten the joint knob.

Once that’s done, you can be 100% sure the powerhead can drive the attachment and the attachment won’t work loose.

Powerheads

Attachments are driven by a powerhead. This unit has an engine, throttle control and a short shaft with a SureLock connector. The difference between the two powerheads comes down to engines: the UMC425 uses a GX25, while the UMC435 has a more powerful GX35. Both engines are Honda Mini 4 Strokes. They can be used in any position like a two-stroke, but they don’t need mixed gas, are easier to start and have a wider powerband.

Attachments

Honda offers 6 attachments to cover lawn care jobs that would normally require rarely-used specialty equipment.

Trimmer: This string trimmer uses a two-line bump feed head and cuts a 16.5-inch wide swath. It can also be used with an optional three tooth grass blade for heavy brush, or use a variety of aftermarket heads by installing an adapter.

Hedge Trimmer: This attachment comes with a double-sided reciprocating blade that is 21.6 inches long. A joint at the end of the shaft allows the blade to be tilted a total of 108 degrees in 18-degree increments so you can get the perfect cut while maintaining a comfortable hand position. The trimmer is available with either a 5.3 inch or 25-inch shaft.

Edger: This attachment uses a standard 9 x 2-inch blade to cut clean edges around pavement and landscape transitions. A metal anti-wear strip protects the gearbox, while a wrap-around blade guard shields the operator from debris.

Cultivator: This mini tiller attachment has tines that are 9.4 inches in diameter and cut a path that’s 6.5 inches wide. With the engine at full throttle, the tines spin at 233 rpm.

Pruner: A 12-inch bar makes quick work of branches, while the 25-inch shaft gives you enough reach for most bushes and small trees. The oil reservoir is translucent, making it easy to check the level and keep the chain lubricated.

Blower: A long shaft, compact fan, and narrow exit make this attachment perfect for skimming across the ground, blowing up loose debris or lifting up layers of wet, matted leaves. Maximum output will vary depending on your powerhead: the UMC425 can drive this attachment to a maximum of 184 mph and 235 CFM, while UMC435 can drive it to a maximum of 235 mph and 250 CFM.

Extensions: Available in 19 and 39 inches, these extensions give you more reach when hedge trimming or pruning.

Warranty

Honda guarantees the powerheads, engines, and attachments for 36 months of residential use or 24 months of commercial use.

Need Something for Your Honda Equipment?

Hondalawnparts.com is more than a website: we’re a certified Honda Engines and Honda Power Equipment dealer, so we’re able to offer the same OEM parts and accessories you get at brick and mortar dealers. Better still, we have most items in stock and we ship across the U.S. and Canada. Our website can show you factory parts diagrams and descriptions specific to your model, making it easy to find just what you’re looking for.

Frequently Asked Questions about Honda Mowers

HRR and HRS Mowers: Honda Quality and Innovation for the Home OwnerIs there something bugging you about your new mower? Do you think you could get better performance from it? These are the most frequently asked questions about Honda mowers from setting them up to getting parts that fit.

Why Can’t I Tilt the Handle Into Place?

The flywheel brake is engaged, which is putting tension on a cable running on the side of the handle. Closing the bail will let you swing the handle into its operating position.

How Do I Discharge Clippings?

Set the Clip Director to “Bag” or “1.” If you don’t have a bag attached to the mower, clippings will fall out of the rear chute onto the ground.

Do I Need a Spark Arrester?

A spark arrester is a metal screen that traps sparks from the exhaust, preventing them from igniting vegetation. These devices may be required in areas experiencing a drought or that have highly flammable plants.

Arresters are not included from the factory, but they can be added to any Honda mower. The arrester attaches to the exhaust opening with a single screw and can be removed for cleaning. Over time, carbon buildup can fill the screen, restricting exhaust flow. This buildup can be removed with a wire brush.

How Do I Charge the Battery in My Mower?

Electric start models use a small battery mounted in a housing below the start button. The mower’s charging system recharges the battery as you mow. During the mowing season, this should be enough to keep the battery ready to start the engine.

Power may drop off during storage, requiring a recharge. This battery is too small to be safely charged with an automotive battery charger. Honda makes a low amp charger specifically for these small batteries. To use it, remove the battery from the starter box and connect it to this charger for 8-24 hours.

How Short Should I Cut My Lawn?

When cutting, the blade should trim the leaves, but not go through stems or crowns. Most turf grasses should be trimmed to around two inches tall.

Limit cutting to 1/3 of the grass’ total length. Cutting more at one time will make it harder for the grass to recover.

How Do I Mow Leaves?

For the best results, mow the leaves before coverage extends past the height of the grass. This may require moving two or three times per week when leaf fall is at its peak.

Lift the front of the mower one or two settings higher than the rear. This helps the deck draw in leaves instead of pushing them away. Set the Clip Director to “Mulch” or “9.” The mulch left by the mower should be broken down fast enough by your lawn that bagging won’t be needed. If you need to bag the leaves, install a leaf shredder in the discharge opening.

How Do I Store My Mower?

Drain any gas left in the tank, carburetor and fuel lines. Depending on your model, you may be able to drain everything by removing the sediment cup on the bottom of the carburetor, or by tilting the mower and letting the gas flow out of the filler neck. Once the fuel system has been drained, start the engine and let it run until it stalls. This removes any remaining fuel. Even if you’re using gasoline mixed with a stabilizer, it will go stale before next spring.

Remove the spark plug and add a few drops of oil to the cylinder. Pull the starter cable a couple times to distribute the oil, then reinstall the plug. It’s normal for the mower to smoke when first starting the engine next season.

It’s a good idea to thoroughly clean the mower and change the oil before putting it in storage. Never put a tarp over your mower. Moisture can collect inside, promoting rust.

Where Do I Find the Model and Serial Number for My Mower?

The model and serial number for the mower are printed on a tag on top of the deck next to the handle. If you’re ordering engine parts, you’ll need to know its model and serial number. The model name is printed on a large sticker on top of the engine cover, while the serial number is stamped into the engine block.

What’s the Best Place to Get Parts and Accessories for My Mower?

Hondalawnparts.com is an authorized Honda Engines and Honda Power Equipment dealer. That means we’re able to ship OEM parts and accessories for your mower straight to your door whether you live in the U.S. or Canada. Our site can find parts based on your model and serial number, and it will show you factory parts diagrams and descriptions, making it easy to find what you need.

Honda’s Cruise Control Hydrostatic Transmission: Making Mower Control Easy

hondahydrostatic

Hydrostatic motors are used in most riding mowers, but walk-behind models have been stuck with clunky geared transmissions. Honda is changing that with their Cruise Control Hydrostatic Transmission. This exclusive feature makes mower speed fully adjustable for better control on hills and around obstacles, and it works with other mower features to make stops and starts easier.

Why Use a Hydrostatic Transmission?

When you want to change your speed when driving a car, you can shift gears or use more or less throttle. You can also do the same thing on a mower, but there’s a problem: if you close the throttle, the engine won’t spin the blade as fast, reducing cutting performance. Instead of setting the speed exactly where you want it, you have to shift the transmission into gear and work around whatever speed it’s going. This makes mowing awkward when going over slopes, as the mower ends up going too slow or too fast. The gears are also too high for slow speed maneuvers, forcing the operator to shut off the drive system and push the mower when operating in narrow spaces and around landscape features.

Hydrostatic transmissions commonly found on riding mowers and wide-area walk-behind mowers get around this by using a hydraulic pump to control drive speed. By changing the amount of fluid pumped by the hydraulic system, the speed can be varied independently of the throttle. The Cruise Control transmission works the same way, but it’s small enough to be used in a regular walk-behind mower.

How Does it Work?

Instead of driving gears, the engine drives a hydraulic pump. This pump has a set of pistons connected to a swash plate. By changing the angle of this plate, the distance the pistons travel changes, increasing or decreasing the amount of fluid they pump. That fluid is used to drive a hydraulic motor connected to the wheels. In effect, it’s like having a second throttle independent of the engine.

With the pump running at its full flow rate, the pump in the Cruise Control transmission can drive the hydraulic motor fast enough to reach a speed of 4 mph. That’s a brisk walking pace.

Less Complicated Than It Sounds

Hydrostatic drive systems in riding mowers often use a combination of pumps, hoses, filters, and motors to drive the vehicle. However, Honda was able to design a complete hydrostatic drive system including the pump and motor into a single unit that’s no larger than a geared walk-behind mower transmission.

This drive unit is sealed, so it requires no maintenance. There’s also no clutch to wear out, nor is there a belt connected to the engine that can slip and break. That means these mowers require less maintenance and have fewer points of failure than a walk-behind with a geared transmission.

Using Hydrostatic Cruise Control

The bail on the top of the handle changes the swash plate angle, increasing speed as it’s closed. The cruise control lever below it limits plate movement, offering 9 settings for maximum speed. Usually, the bail will be fully engaged, so the mower speed will be the maximum set by the cruise control. The lower the cruise control setting is, the finer the speed adjustment is using the bail. This gives the mower precision control when operating in areas filled with obstacles without being erratic at high speeds.

All models that have a hydrostatic transmission also come with the Roto-Stop blade stop system. This uses a clutch between the blade to the engine shaft, stopping the blade when the operator leaves the controls. With both the blade and bail disengaged, the engine can keep running without cutting or rolling away. When you return to the mower, you don’t need to restart the engine, and you can squeeze the bail to return to your original mowing speed as set, using the cruise control lever.

Which Models have a Cruise Control Hydrostatic Transmission?

Currently, Honda fits this transmission to the HRX217HYA, HRX17HZA, and HRC216HXA.

When You Think “Honda,” Think “Honda Lawn Parts”

Honda Lawn Parts is an authorized Honda Engines and Honda Power Equipment dealer so we can supply you with what you need for your mower, generator, snowblower, pump, trimmer or engine. Our site has factory information built-in including parts diagrams and descriptions, making it easy to find exactly what you need. Whether you’re in the US or Canada, you have parts shipped to your door by visiting www.hondalawnparts.com.