Proven: How to Get Tar Out of Lawn Mower Fast (2026)

By Elena Rodriguez · January 4, 2026

Immediate Action (First 5 Minutes)

I still remember the sinking feeling I got last July. I was finishing up the back acreage of my property before a massive thunderstorm hit. My Toro TimeCutter was humming along perfectly. Then I noticed the engine bogging down and heard a low, rhythmic thumping noise. I shut it off, popped the deck, and saw a massive, sticky black clump of road tar wrapped around the spindle and blade. If you've ever driven over a fresh asphalt patch or a tar snake on the road, you know exactly what I'm talking about.

Tar is essentially a petroleum-based adhesive. It binds to metal, cures in the heat, and throws your mower blade completely out of balance. An unbalanced blade vibrating at 3000 RPM will destroy your spindle bearings in a matter of hours. You have to act fast. Don't just park the mower and hope it hardens. The longer it sits in the hot sun, the more it bakes onto the steel.

Your first move is safety. Disconnect the spark plug wire immediately. I always use a 5/8-inch spark plug socket to remove the plug entirely when I'm doing heavy deck work. This guarantees the engine won't accidentally turn over while your hands are near the blade. Next, grab a stiff putty knife and scrape off the thickest, softest layers of the tar while it's still somewhat pliable. You won't get it all. Just remove the bulk of the mass to stop the severe vibration.

What You'll Need (Tools and Products)

Gathering the right supplies before you start saves you from walking back and forth to the garage with greasy hands. I've tested dozens of solvents over my ten years of maintaining commercial and residential equipment. This isn't the cheapest option on the shelf, but using the right chemical makes the job ten times easier. You'll need heavy-duty nitrile gloves, eye protection, and a well-ventilated workspace.

Here is my exact toolkit for this job. I keep a dedicated 5-gallon bucket in my shed just for deck cleaning supplies.

WD-40 Specialist Heavy Duty Citrus Degreaser: This is my go-to. It costs about $12-15 for a 20oz can. It cuts through petroleum without stripping paint.
Mineral Spirits: A great backup solvent. A quart costs around $8-10 at any hardware store.
Stiff Putty Knife: Get a 2-inch or 3-inch metal scraper. Plastic won't cut it.
Wire Brush: A short-handled stainless steel brush works best for the tight corners around the spindle.
Shop Towels: Don't use your good rags. Tar will ruin them permanently. Buy a box of heavy-duty blue shop towels.

Solvent Comparison Table

Solvent Type	Avg Price	Paint Safe?	Effectiveness
Citrus Degreaser	$12 - $15	Yes	Excellent
Mineral Spirits	$8 - $10	Mostly	Very Good
Goo Gone Automotive	$6 - $8	Yes	Good (Small spots)
Gasoline	$3 - $4	No	Dangerous/Poor

Step-by-Step Removal

I'll be honest, this takes elbow grease. You can't just spray it and walk away. Follow these steps exactly to get your deck looking factory-fresh without damaging your engine components.

Step 1: Prep and Tilt Safely

Disconnect the spark plug. This is non-negotiable. Once the plug is out, you need to tilt the mower to access the deck. Always tilt the mower with the carburetor and air filter facing UP. If you tilt a Honda GCV160 or Briggs & Stratton engine the wrong way, oil will flood the carburetor and soak your air filter. Then you'll be cleaning a carburetor too. Prop the mower securely against a sturdy workbench or use a dedicated mower lift.

Step 2: Mechanical Scraping

Take your metal putty knife and aggressively scrape the large chunks of tar. Push the blade flat against the steel deck to avoid gouging the metal. Focus on the areas around the blade tips and the spindle housing. Drop the chunks into a cardboard box or a heavy trash bag. Don't drop them on your driveway, or you'll just track them back into the house.

Step 3: Apply the Solvent

Shake your can of WD-40 Specialist Citrus Degreaser well. Spray a thick, generous coat directly onto the remaining tar residue. Make sure you get it into the tight crevices where the blade spindle meets the deck. Let it sit for exactly 10 to 15 minutes. The citrus solvents need time to break down the petroleum bonds. If it's a very hot day, the solvent might evaporate quickly, so spray a second light coat after 7 minutes.

Step 4: Agitate and Scrub

Grab your stainless steel wire brush. Scrub the softened tar in tight, circular motions. You'll see the black sludge start to lift and turn into a messy paste. Wipe the brush clean on a rag every few strokes. For the flat surfaces of the deck, use a stiff-bristled nylon brush or a Scotch-Brite pad to avoid scratching the paint. Keep wiping away the dissolved sludge with your blue shop towels.

Step 5: Clean the Pulleys and Belts

Tar loves to wrap around the small grooves of the PTO pulley. If you leave it there, your drive belt will slip and burn up. Use an old toothbrush dipped in mineral spirits to scrub the pulley grooves. Wipe the drive belt down with a damp rag. Never spray solvent directly onto the rubber belt, as it will degrade the rubber and cause it to snap.

Step 6: Rinse, Dry, and Lubricate

Lower the mower back to the ground. Use a standard garden hose with a spray nozzle to rinse the underside of the deck. Avoid using a high-pressure washer, as the extreme force can blow water past the spindle seals and ruin the bearings. Let the deck air dry completely in the sun. Once it's bone dry, spray a light coat of silicone lubricant or a dedicated mower deck spray to protect the bare metal.

Alternative Methods

Sometimes the standard chemical route doesn't work, especially if the tar has been baked onto the deck for months. Here are a few backup methods I've used when the citrus degreaser just isn't cutting it.

The Heat Gun Method

Tar softens significantly when heated. I use a Porter-Cable heat gun set to exactly 200°F. Hold the gun about 4 inches away from the tar clump and move it continuously. Once the tar starts to bubble and melt, scrape it off with your putty knife. Be extremely careful not to overheat the metal, as you can easily blister the factory paint on your mower deck. Keep a wet rag nearby to cool the metal if it gets too hot.

The Dry Ice Trick

This is a wild trick I learned from an old small-engine mechanic. Buy a small block of dry ice from your local grocery store (usually around $15-20). Put on heavy leather welding gloves and press the dry ice directly against the tar clump for about 60 seconds. The extreme cold freezes the tar, making it incredibly brittle. Take a rubber mallet and tap the frozen tar. It will shatter and pop right off the metal in clean chunks. It's highly effective but requires careful handling.

Peanut Butter for Tiny Spots

If you only have a few tiny flecks of tar on the painted exterior of the mower, grab a jar of creamy peanut butter. The natural oils in the peanuts break down the tar's adhesive properties. Smear a thick layer over the spots and let it sit for 20 minutes. Wipe it away with a microfiber cloth. It smells great, but it's completely useless for the heavy clumps underneath the deck.

Prevention Tips

Cleaning tar off a mower deck is a miserable chore. Preventing it from sticking in the first place is a much better use of your weekend. I treat my mower deck at the start of every single season, and it pays off massively.

First, invest in a high-quality mower deck spray. Fluid Film and Mo-Deck are the two brands I trust most. They cost about $15-20 a can. Spray the entire underside of the clean, dry deck before your first mow. This creates a slick, non-stick barrier that prevents grass, mud, and tar from bonding to the steel. Reapply it every four to six weeks during the mowing season.

Second, be mindful of where you mow. If your neighborhood is getting fresh asphalt repairs or tar crack-filling, avoid mowing the edges of the road for at least a week. If you have kids who leave plastic toys in the tall grass, do a quick walk-around before you start the engine. Hitting a melted plastic toy creates a mess that is just as stubborn as road tar.

Finally, wash your deck monthly. Hook up your garden hose to the deck wash port if your mower has one. Run the engine and engage the blades for three minutes. This flushes out the acidic grass clippings that eat away at your protective coatings and expose bare metal to sticky substances.

Frequently Asked Questions

Can I use a pressure washer to blast the tar off my mower deck?

I strongly advise against using a high-pressure washer directly on tar clumps. The extreme pressure will just smear the sticky mess deeper into the spindle bearings and belt pulleys. Stick to a standard garden hose with a spray nozzle for the final rinse after you've dissolved the bulk of the tar.

Will a thick layer of tar ruin my mower blade permanently?

Tar itself won't corrode or dull the steel of your mower blade. However, the uneven weight distribution causes severe vibrations that will quickly destroy your spindle bearings and stretch your drive belts. You must remove it completely to restore the blade's factory balance.

Is gasoline a good solvent for cleaning tar off outdoor equipment?

While gasoline will technically dissolve petroleum-based tar, it is incredibly dangerous and highly flammable. It also strips away all the essential factory lubricants from your moving parts and can easily damage painted surfaces. Always use a dedicated citrus degreaser or mineral spirits instead.

How often should I apply a preventive deck spray during the mowing season?

I recommend applying a fresh coat of mower deck spray every four to six weeks during peak growing season. If you frequently mow through wet, thick grass or near construction zones, you should reapply it every three weeks. A quick visual inspection of the deck underside will tell you when the coating is wearing thin.