Common faults and solutions for HOWO vacuum trucks

What's the worst thing about sewage collection? It's not the hard work or the dirt, but the truck being stuck next to a cesspool, the pipes in a well, and the pump not working. Not only does this delay the work schedule, but many people mistakenly assume the pump is broken or the machine is unusable when the truck malfunctions, and immediately call for major repairs, wasting money and time.

In fact, the Howo vacuum truck chassis and vacuum system are very stable. 90% of common faults are not hardware damage, but rather caused by operation and minor daily issues. Today, we've summarized several core problems frequently encountered by drivers, along with practical methods that can be solved on-site without disassembling the machine. Both novice and experienced drivers can use them directly.

Fault 1: Vacuum pump runs with weak suction

★ Phenomenon: All parts work normally, vacuum pressure is too low, pipeline gurgles and fails to suck waste.

★ Causes: Air leakage, improper valve position, worn pump parts, blocked pipelines and abnormal vacuum oil.

★ Solutions

• Stop power take-off, clean filter and pipeline debris

• Switch four-way valve to suction position

• Check and repair air leakage seals

• Replace worn pump components

• Clear blocked overflow valve and water-gas separator

• Top up or replace vacuum pump oil timely

★ Prevention Tips: Clean filter after use, inspect pump and oil regularly

Fault 2: Can run dry and suck air, but cannot pump thick sludge or sewage.

★  Main causes:

• Negative pressure in the tank is not fully built up before suction starts.

• Suction inlet is pressed tightly against the tank bottom with no air intake space.

• Thick, settled sludge has hardened and not been loosened.

★  Corrective operations:

• Run the pump idle for 30 seconds before operation to build up sufficient negative pressure in the tank.

• Keep the suction inlet 3–5 cm above the tank bottom to avoid full contact.

• For thick sludge, first dilute with water to loosen it, then raise and lower the inlet while pumping. Do not force suction.

Fault 3: Pump overheats, makes abnormal noises during operation

★ Real-world symptoms: After working for a short time, the pump temperature spikes, accompanied by a buzzing noise. New operators, fearing pump burnout, immediately stop work, unnecessarily delaying the project.

★ Real causes: Often caused by prolonged idling, impurities inside the pump, worn vanes/shrouds, insufficient or deteriorated lubricating oil. Disassembly, cleaning, or replacement of easily worn parts is required.

★ On-site solutions:

• If impurities or debris enter the pump chamber, disassemble, clean the vacuum pump, and replace worn parts.

• Replace worn vane sleeves promptly.

• Add or replace clean lubricating oil if insufficient or contaminated.

Fault 4: Vacuum gauge shows no reading or abnormal reading

★ Possible causes include gauge body damage, gauge tube blockage, insufficient vacuum pump speed, or four-way valve malfunction. Each possibility needs to be checked individually.

★ Solutions:

• Vacuum pump speed too low: Solution: Increase throttle;

• Vacuum gauge tube blockage: Solution: Remove blockage;

• Damaged vacuum gauge: Solution: Replace vacuum gauge;

•  Four-way ball valve not fully open: Solution: Replace vane.

Fault 5: Sewage Backflow After Pumping Stops

★ Symptom: After the pump is turned off, sewage flows back into the pump from the suction pipe.

★ Common Causes

• The suction port was not pulled out of the liquid surface in time.

• The anti-overflow valve is malfunctioning: the float is stuck or the seal is not tight.

• The four-way valve has not returned to its original position, and the pipeline is still open in the tank.

★ Solutions

• When the tank is almost full, pull the suction pipe out of the liquid surface first, then turn off the pump.

• Check/replace the anti-overflow valve assembly to ensure it automatically closes when the tank is full.

• Before stopping the pump, switch the four-way valve to the **"Stop/Sealed" position**.

Fault 6: Rear tailgate cover leak 

★ This is often caused by a loose left-hand screw, an aged and ineffective gasket, or improper adjustment of the tie rod (adjusting the tie rod length). The seals should be tightened or replaced.

Fault 7: PTO  abnormal noise, high temperature, unable to engage gears

★ Common Causes

• Gear/bearing wear.

• Insufficient/deteriorated lubricating oil.

• Improper operation: clutch not fully depressed, engaging gears at too high an RPM.

★ Solutions

• Check the oil level, add or replace with dedicated gear oil.

• Severe abnormal noise → disassemble, inspect, and replace worn parts.

• Gear engagement: fully depress the clutch, engage at idle speed or with slight acceleration, avoid forcing the gear.

Fault 8: Hydraulic system malfunction

This involves oil leakage from the cylinder, stuck hydraulic valves, and failure to transmit power from the power take-off. It is necessary to check the pipeline seals and the working status of the hydraulic pump.

Daily Quick Troubleshooting Guidelines(important)

1. Check Valves: Are the four-way valve, anti-overflow valve, and vent valve in the correct positions?

2. Check Pipes: Check for leaks and blockages in the suction pipe, joints, and gaskets.

3. Check Pumps: Check oil level, oil quality, vacuum level, unusual noises, and overheating.

4. Check Transmission: Check the power take-off, belt, and speed.

5. Check Seals: Check the seals of the tank opening, rear cover, and anti-overflow valve.