How To Tell If A Riding Lawn Mower Engine Is Seized

You purchased a riding lawn mower for its power and ease of use so the last thing you want from your high-priced mower is a seized engine. Riding lawn mowers are made to be convenient yet when they experience technical issues, they can be costly and impractical.

If you think your engine is seized, first try to diagnose your lawn mower’s issue. To do this, begin with removing the spark plugs to see if the lawn mower will start without them.

You can tell that your lawnmower engine is seized if the piston or cylinder is stuck. Inspect the blades for debris, rocks, or grass that can cause your lawnmower engine to seize. Look at your carburetor and check for corrosion or clogs that will make the engine seize.

What Can Cause a Lawn Mower Engine to Seize?

Lawn mower engines can seize for a number of reasons, anything from:

  • Low fuel
  • Low/high oil levels or hydro-lock
  • A corroded or plugged carburetor
  • A wet spark plug
  • An obstructed blade
  • A stuck piston

The issue might not even be a seized engine but instead, a drain plug is disconnected.

How To Locate and Determine the Issue

To locate your lawn mower’s issue, start by examining the inside of the carburetor. If the fuel filter is obstructed or the carburetor inlet needle is stuck, the mower will be unable to get gas.

1)Check The Fuel Level

90% of lawnmowers won’t start is due to no to low fuel. Check your fuel line you start taking apart your lawnmower.

2) Check The Oil Level for Hydro-Lock

Here’s how to check for and drain the excess oil and fix hydro-lock:

  • Put on a pair of leather gloves for safety
  • Remove the spark plug
  • Crank the engine—excess oil will spray out of the spark plug hole

Hydro-lock typically occurs when a lawnmower is held in a forward tilted position for more than a few minutes at a time.

3)Examine The Carburetor

Check For Clogs

Lawn mower carburetors should be checked regularly. Lawn debris can clog the air filter and stop the flow of gas.

Here’s how to remove debris from a clogged carburetor:

  1. Put on a pair of leather gloves for safety
  2. Remove the spark plug
  3. If your lawn mower is equipped with a fuel filter, remove the fuel line at the carburetor
  4. If gas begins to flow, your fuel filter is clogged, and you’ll need to clean or replace it
  5. If the gas does not flow, remove the fuel line before the fuel filter inlet. If gas begins to flow this time, check to see if there is fuel in the bowl.
  6. If the bowl is empty, the problem is likely a stuck inlet needle (you’ll need to clean or replace it).
  7. If the gas still does not flow, the fuel line is likely obstructed.
  8. Look inside the tank for anything that might be obstructing the vent and discard it.

Check For Corrosion

Carburetors can also become corroded from oxidation or not being stored properly. If you see powder-like corrosion on the carburetor, then you may need to replace it. A corroded carburetor is typically irreparable—but not always.

You can try to clean a corroded carburetor using this DIY method:

  1. Put on a pair of leather gloves for safety
  2. Remove the spark plug
  3. Remove the carburetor and dismantle it
  4. Boil the parts in vinegar for 30 minutes

4)Inspect the Spark Plug

If your spark plug gets wet, it will not fire and seize the engine. You can try to clean and dry your spark plug or replace it to restore normal engine operation.

To safely remove and check the spark plug, put on a pair of leather gloves. Then, remove the spark plug. Finally, check the spark plug for moisture.

Is the spark plug is wet?

  • Dry and clean the spark plug with a carburetor cleaner
  • Reinstall the spark plug
  • Try starting the lawn mower again

5)Examine the Blades

Small rocks or other lawn debris can get lodged between the blade and the lawn mower’s deck and seize the engine.

To check for any blade obstructions safely, put on a pair of leather gloves. Next, remove the spark plug. Then, lift or turn the lawn mower on its side to check for blade obstructions.

6)Inspect the Piston

If the piston has seized, you can try to manually free it by rocking the blade. To safely do this:

  • Put on a pair of leather gloves
  • Remove the spark plug
  • Spray a sufficient amount of a carburetor penetrating oil or spray lubricant into the spark plug hole
  • Wait an hour before trying the blade
  • If the blade turns, spin it a few times slowly and reinsert the spark plug
  • Try starting the lawn mower again

Related Questions

How long does the average riding lawn mower last?

The average riding lawn mower will last between 8 to 10 years when properly maintained. If the lawn mower is not properly maintained, it should last between 4 to 5 years.

Is buying a riding lawn mower worth it?

You might be wondering if it’s worth splurging for a riding mower. Walk-behind mowers typically cost less and consume less gas. However, they can make the chore of cutting grass tiresome. Many homeowners find investing in a riding lawn mower is well worth the splurge because it allows them to mow the lawn quickly with minimal effort.

If you have more than a one-half acre of grass to cut, it’s probably worth it.

How much does a new riding lawn mower cost?

A shiny new riding lawn mower will typically cost you more than $2,000. There are a few basic models that run between $1,000 to $1,500.

How much does it cost to fix a riding lawn mower?

The average cost for a lawn mower repair is around $60 per hour. When hiring a lawn mower repair specialist to fix your riding lawn mower, plan to spend between $40 and $90 per hour.

What is the best time of year to buy a riding lawn mower?

Lawn mowers are typically cheapest when their demand is low. That means, the best time to buy a lawn mower is early fall or after summer. Huge discounts usually start showing up in September.

The Bottom Line

Small repairs can make a big difference in how a riding lawn mower operates. Before heading to the lawn mower repair shop with a seized engine, you might be able to diagnose and fix the issue on your own.

By checking the carburetor, spark plugs, and fuel pump yourself could save you a lot in repairs. It might not even be an engine issue at all.

If you get the lawn mower started, be sure to run it for at least five minutes. And, if you still can’t get your lawn mower started, then it’s probably time to head to the repair shop.