How Often Should You Service a Hydrovac Truck? Maintenance Intervals Explained

Every hydrovac owner asks me the same question: "How often should I really be servicing this thing?" The manufacturer says one thing, the dealer says another, and the guy down the road says he changes oil once a year and it's fine.

Here's the truth: it depends. Not a helpful answer, I know. But after 25 years of fixing hydrovac trucks, I can tell you exactly what it depends on and how to figure out the right intervals for your specific situation.

The Two Ways to Track Service

Service intervals are usually given in two formats:

• Time-based: Every 3 months, 6 months, annually
• Hour-based: Every 200 hours, 500 hours, 1000 hours

The rule: Whichever comes first wins.

If you change blower oil every 200 hours but only run 100 hours a year, you still change it at least annually. Time degrades oil even if the truck isn't running.

If you run 60 hours a week, you're not waiting 6 months for an oil change — you're doing it every 3-4 weeks based on hours.

Critical Interval: Blower Oil

This is the one people screw up most often, and it's the most expensive mistake.

Recommended: Every 200 hours or monthly, whichever comes first

Reality check:

• Running 40+ hours/week? Change it every 3-4 weeks
• Running lighter duty? Monthly is fine
• Harsh conditions (dust, extreme temps)? Consider 150-hour intervals

Why it matters: Blower oil breaks down under the heat and pressure inside your PD blower. Old oil doesn't lubricate properly. Poor lubrication means worn lobes and bearings. Worn internals mean no vacuum and an $8,000-12,000 rebuild.

A blower oil change costs about $50 in materials and 30 minutes of time. A blower rebuild costs months of your truck's earnings.

Engine Oil and Filter

Recommended: Per engine manufacturer specs (usually 10,000-15,000 miles or 250-500 hours)

Reality for hydrovacs: Your engine works harder than a typical truck engine because it's running the PTO under load constantly. I recommend:

• Heavy use (50+ hours/week): 200 hours or 5,000 miles
• Moderate use (25-50 hours/week): 300 hours or 7,500 miles
• Light use: Manufacturer interval, but at least every 6 months

Oil analysis option: If you want to optimize your intervals, send oil samples to a lab. They'll tell you exactly when your oil is wearing out. Cost is about $25-30 per sample, and it can save you money if your oil is lasting longer than you thought — or catch problems if it's breaking down early.

Hydraulic System

Hydraulic Fluid Change:

• Recommended: Every 2000 hours or 2 years
• Reality: Depends heavily on conditions and contamination

Hydraulic fluid lasts a long time if the system stays clean. But if you're running in dusty conditions, have any contamination events, or see fluid degradation (dark color, burnt smell), change it more often.

Hydraulic Filter:

• Recommended: Every 500 hours or 6 months
• Reality: Check condition regularly; replace when dirty or on schedule

A clogged hydraulic filter causes pressure drops and can kill your pump. These filters are cheap insurance.

Hydraulic Fluid Analysis: Like engine oil, you can have hydraulic fluid analyzed. Useful for large systems where fluid change is expensive.

Air Filters

Engine Air Filter:

• Recommended: Inspect every 100 hours, replace as needed
• Dusty conditions: Check weekly

A clogged air filter restricts airflow, reduces power, and increases fuel consumption. Severe restriction can damage the engine. Most trucks have a restriction indicator — pay attention to it.

Cab Air Filter:

• Recommended: Every 6 months or annually
• Don't forget this exists. Your operators breathe that air.

Fuel Filters

Primary Fuel Filter:

• Recommended: Every 500 hours or 15,000 miles

Secondary Fuel Filter:

• Recommended: Every 250 hours or 7,500 miles (if equipped)

Modern diesels are sensitive to fuel contamination. Diesel fuel system problems often start with clogged filters. Don't stretch these intervals.

Water System

Water Strainer/Filter:

• Recommended: Check weekly, clean as needed
• Reality: Clean it constantly if using non-municipal water

A clogged strainer kills water pressure. I've lost count of the water pressure calls that were just dirty strainers.

Water Pump Service:

• Recommended: Inspect seals and packings every 500 hours
• Reality: Most pumps run 2000+ hours before needing service if maintained

Water Tank:

• Flush annually at minimum
• More often if using non-municipal water or experiencing algae growth

Brake System

Brake Inspection:

• Recommended: Every 3 months or per DOT requirements
• Pad/Lining Replacement: When worn to minimum thickness
• Brake Fluid (hydraulic brakes): Every 2 years
• Air Dryer (air brakes): Replace desiccant annually

Brakes are safety-critical. Don't stretch these intervals.

Cooling System

Coolant Change:

• Recommended: Per coolant type (2 years for conventional, 5+ years for extended life)
• Reality: Test annually, change when protection levels drop

Cooling System Inspection:

• Hoses: Check monthly for soft spots, cracks, leaks
• Radiator/Cooler: Clean externally as needed (monthly in dusty conditions)
• Belts: Inspect monthly, replace when worn

Greasing

This gets forgotten more than almost anything:

Boom Pivots, Steering, Suspension:

• Recommended: Weekly or every 50 hours
• Reality: Do it. Just do it. Dry pivots wear out fast.

Get a real greasing schedule. Hit every fitting every week. Takes 15 minutes and prevents hundreds of dollars in wear.

Debris Tank and Vacuum System

Door Seals:

• Inspection: Daily (part of pre-trip checklist)
• Replacement: When they fail the dollar bill test

Relief Valve:

• Inspection/Cycling: Daily in cold weather, weekly otherwise
• Rebuild/Replace: When sticking or not sealing properly

Tank Inspection:

• Interior: Annually (check for corrosion, wear)
• Exterior: Monthly (check for damage, rust)

Adjusting for Your Conditions

Manufacturer intervals assume normal conditions. Your conditions might not be normal:

Shorten intervals if:

• Running in extreme dust
• Operating in extreme heat or cold
• High-hour operation (50+ hours/week)
• Using the truck for particularly demanding work
• Older equipment with higher wear

You might extend intervals if:

• Light-duty operation
• Controlled, clean environment
• Newer equipment in good condition
• Oil analysis shows fluid still in spec

The Real-World Schedule

Here's what I tell operators in Pennsylvania and my service area:

Weekly (every Friday afternoon):

• Check all fluids
• Grease all fittings
• Clean water strainer
• Inspect belts and hoses
• Review any issues from the week

Monthly:

• Change blower oil
• Detailed inspection
• Check battery condition
• Clean cooler fins
• Safety equipment check

Quarterly:

• Engine oil and filter (adjust based on hours)
• All other filters checked/replaced
• Brake inspection
• Full safety inspection

Annually:

• Coolant system service
• Full professional inspection
• DOT inspection (if applicable)
• Major component inspection

Tracking Hours

Your hour meter is your maintenance trigger. Pay attention to it.

• Log hours weekly
• Set service reminders based on hours, not just dates
• If the hour meter breaks, fix it immediately

Not sure how many hours you're running? Track it for a month. Knowing your usage pattern is essential for setting the right intervals.

When to Get Professional Help

Some maintenance you can do yourself. Some needs a pro:

DIY-friendly:

• Fluid checks and top-offs
• Filter replacements
• Greasing
• Belt inspection
• Basic inspections

Get professional help for:

• Anything inside the blower
• Hydraulic pump service
• Engine work beyond basic maintenance
• Brake system work (liability)
• Electrical diagnosis
• Annual comprehensive inspection

I offer maintenance programs for fleet operators in PA, NJ, NY, and the DC/Maryland area. We handle the scheduled maintenance so you can focus on running your business. Call me at 272-296-9637 to discuss what makes sense for your operation.

The Bottom Line

Service intervals aren't arbitrary numbers — they're based on how long components can run before they start degrading. Stretching intervals saves money short-term and costs money long-term. Following intervals costs money short-term and saves money long-term.

I've rebuilt a lot of blowers, pumps, and engines that would still be running if someone had just changed the oil on time. Don't be that operator.

For more on hydrovac maintenance, check out the complete maintenance guide and specific guides on blower oil and operator habits that affect service life.