How to unseize an engine that ran out of oil

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One of the biggest causes of seizures is the engine running out of oil or having an insufficient oil supply.

Luckily, a locked engine due to oil drying out is not a lost cause and it’s possible to free up both larger and small engines with a bit of effort.

This article will teach you how to unseize an engine that ran out of oil and save yourself an expensive engine repair/replacement cost.

How to check if the engine is really stuck?

Like with any other troubleshooting projects, it’s important to test and confirm that the problem is truly a seized engine before moving on.

The check isn’t involving in any way.


  1. Ensure you have parked the vehicle or lawn mower in a safe area.
  2. Pull out the spark plug (or plugs).
  3. Attempt to rotate the engine. You can use your bare hands or a breaker bar. The latter is ideal for big engines such as car engines.
  4. Know that the engine is laid out if you have no success when you try to make it turn.

How to unseize an engine that ran out of oil

What is great about the whole process is that there are a couple of approaches you can try if one doesn’t work.

Some of the solutions are much easier and we recommend that you start with them before attempting the more advanced tactics.

Method 1: Use penetrating oil to rescue your engine

Penetrating oil has low viscosity and can be handy any time you have rusted mechanical parts to free.

You can try it first because the procedure of applying the fluid is incredibly easy.

Precautionary measures:

  • Wear leather gloves to protect your hands.
  • Also, wear goggles just in case the fluid hits your eyes. 

Steps- for most engines:

I have had some luck soaking the cylinder in penetrating oil and you could be successful too.

The best way of pouring oil directly into cylinders is via the spark plug holes.

For this reason, you need to take out the spark plugs so that’s where you’ll start.

Remember to pour the oil lavishly.


  1. Play the waiting game- let the thing absorb the penetrant for a week or even two weeks. You might even shower it with more liquid every few days (some do it daily) to intensify the penetration.
  2. At the end of the two weeks, make an effort to make the crankshaft spin. It should escape the seizure and turn unless it was impaired beyond redemption.
  3. Put in adequate oil, return the spark plug (s), and start the engine.

Tip: Do not give up on the engine just because it didn’t budge on the first trial. Continue wetting the cylinder for 2 more weeks and take another stab. This works every so often.

Steps- for lawn mower engines:

  • Remove the spark plug.
  • Grab your container of penetrating oil and of spray the hole where the spark plug goes generously.
  • Let it sit for about 10 minutes
  • Try to rock the blade. Do this repeatedly but without forcing things until you feel it beginning to turn.
  • Now spin it a couple more times (still carefully) in the direction it normally rotates.
  • Replace the spark plug into the hole, add the recommended amount of oil, and make a fresh attempt to start the mower.

This works in many cases (where the engine is not irreparably hurt) and could free the piston.

How to unseize an engine that ran out of oil-alternative methods

Approach 1:

  • Fill the bores with diesel.
  • Let it sit for at least 7 days.
  • With a breaker bar, try to have the crank turn. It’s advisable to rock the bar back and forth gently when doing this.

This may again stop the seizure except where an essential – the piston, bores, rings, etc.- is crippled.

Approach 2:

If you’re yet to have it break it free, consider doing a bit of more difficult dismantling work.

The idea is to get the cylinder head out as well as the crank, depending on the situation.

Precautionary measures:

Don’t let dust particles find their way into the engine all along (as you’re working on it) as it may introduce new complications.


  • Remove all parts near the cylinder head. You don’t want them to interfere with the process. 
  • Unbolt the intake, exhaust manifolds, as well as the valve covers to access the cylinder.
  • Loosen the nuts securing the head then carefully lift the head off (seek a helping hand if necessary).
  • Place a piece of wood on the piston (put it on top) to shield it.
  • Whip out a mallet and strive to hammer the piston out.
  • Hopefully, the damn thing slides out and frees up the engine.

Note: If possible, consult your engine’s handbook to verify the details since steps vary slightly from one engine make to another.

Tip: This is going to be far much easier if you can track the stuck cylinder either by observation or other criteria (multi-cylinder engines). In such a case, you won’t need to bother with the good cylinders and you’ll surely take less time.

How to check a spark plug on a lawn mower

Frequently asked questions

How to tell if riding lawn mower engine is seized

The piston in the mower engine gets seized too if you somehow do not remember to add oil to your riding mower.

To be sure if it’s indeed seized, run the following checks:

  • Physical inspection– it’s likely seized if a visible check on the piston reveals some distortion.
  • Start it and listen for noises – try to turn its key and bear all ears for grinding, ticking, or such sounds that tell you’ve a seized engine in your hands.
  • Bypass the spark plug– I had narrated how you can start the engine with the spark plug removed. Do this and thank your stars if the mower turns over.
  • Check if the pulley turns– another sign is a pulley that feels stuck or extremely difficult when you try to turn it.

In all the methods, we advise that you exercise the patience of a saint and being careful not to cause other damages to the engine.

Unfortunately, the engine may already be hurt beyond repair if none of these procedures work.

If this is the case, your only remaining bet is an expert.

how to change a spark plug on a lawn mower

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