Generator Care Generator Troubleshoot

9 Reasons Your Generator is Burning Too Much Oil (Solved)

Generator engine oil’s sole purpose is to lubricate its internal parts as they rotate to run the generator. However, the oil is bound to find its way to the combustion chamber, to allowed levels. But when you add oil frequently or start to see white smoke out of your generator exhaust, then you know your generator is burning too much oil.

Why is my generator burning too much oil? The best answer is, some parts of your generator engine, such as valve seals, oil rings, head gasket, and piston or cylinder, are worn out, and they are leaking oil to the combustion chamber. It could also be you put too much oil flooding the engine.

When the engine piston moves at high speeds, it creates a vacuum effect that’s at the center of everything about your generator burning too much oil. In this post, I will take you through some of the scenarios on how and why your generator is burning oil in the first place. Be sure to read along!

Why is a Generator Consuming Too Much Oil?

All types of generators consume some oil when they’re in operation. Some generators even indicate it in their manual. Generac, for example, says you can expect your Generac generator to consume anything between 1/2 and 3/4 quart oil when you operate it over 24 hours continuously.

That’s an acceptable level. But when the low-oil shutdown sensor keeps shutting down the engine because of low oil level, unlike before, and you’re getting white smoke, then you have a problem. Your generator is burning too much oil.

If that is the case, here are the problems you need to be aware of and the best ways to troubleshoot them.

1) Damaged or Worn-Out Valve Seal

Engine valves control the opening and closing of the intake and the exhaust during the intake and exhaust strokes.

Because of these movements, they also need to stay lubricated. The lubrication oil comes from the crankcase and drips down from the top.

On the top side of the valves are small rubber seals that prevent the oil from entering the combustion chamber.

If the rubber seals were compromised, cracked, or worn out, the lubrication oil could drop right through to the combustion chamber.

And considering the vacuum effect created by the piston movement, a considerable amount could get burned at every combustion stroke.

And because of this, your generator will be burning too much oil.

How to Fixing the Leaking Valve Seals

The best solution is to replace them. Changing the valve seals shouldn’t be challenging in most generators. All you need is the right set of wrenches mentioned in the generator manual. You will also need to take off the generator engine or the cylinder head for easy access, depending on its placement.

  • Remove the spark plug.
  • Loosen the bolts holding the rocker cover, remove it and set it aside.
  • Rotate the crankshaft until the valve rocker arms are loose.
  • Unscrew and remove them.
  • Detach the valve caps (if yours have them) and set them aside.
  • Press and rotate the valve retainer to release and lift them off.
  • Lift the springs and the spring seat.
  • You should have access to the small. Using needle pliers, pull out the rubber seals from the valve stem.
  • Take the new ones, apply some grease and insert them into the valve stems.

2) You’re using incorrect oil

The number two reason your generator is burning too much oil is, you’re using incorrect oil. You might be adding the correct quantity or even more, but the wrong weight.

If the oil type you’re using is lighter weight than the manufacturer rated or what the weather calls for, it might bypass the piston rings into the combustion chamber.

When the thin oil splashes out of the crankcase to the other parts of the engine, the oil will bypass the three rings. It then gets on top of the piston before getting compressed and burned with the carburetor’s air-gas mixture.

If you suspect using lighter oil, check your generator manual or inquire with your generator manufacturer for the recommended oil weight for your unit.

Also, consider buying the oil from reliable manufacturers with a reputation for providing quality engine oil.

3) Worn-Out or Damaged Piston Rings

Another reason the generator is burning oil might be that its piston rings or the cylinder wall are compromised.

The three rings around the piston head prevent the oil from entering the combustion chamber and the exhaust from entering the crankcase.

When the rings reduce in size even half a millimeter or break such that they don’t expand enough, the space left can allow the oil to reach the combustion chamber and burnt with the air-gas mix.

These rings aren’t perfect; they have a gap that allows them to slightly stretch out and clasp back when you wear them onto the piston.

However, if you mistakenly align the tiny gaps in a straight line during a replacement, the setup might leak oil into the combustion chamber. So, it’d be best to stagger the rings gaps around to avoid this.

4) Worn-Out or Damaged Piston Head or Cylinder Wall

The same can happen if the piston, the cylinder wall, or both are scored. The carbon build-up insider the combustion chamber or debris from the fuel can accumulate and create chucks. When the piston moves up and down, it grinds against these chunks, thus scoring the surfaces.

In such a situation, the scrub-off ring won’t collect all the oil from the piston and the cylinder wall. And because of the vacuum effect created by the piston movements, the oil reaching the combustion chamber could increase depending on the scores on these two parts.

How to fix scored piston head or cylinder

Unfortunately, this is an expensive and skilled fix that requires you to take apart your generator and replace these parts. The parts themselves can be expensive as they have to match your generator’s brand and build.

5) Blown Head Gasket

Another part of the generator that, when compromised, can leak oil to the combustion chamber is the head gasket, especially when internally blown.

If the head gasket is blown out inside and out, it can exhale exhaust from there and breathe in the air avoiding the carburetor route.

But for an internally blown head gasket, especially near the pushrods, the oil that lubricates the valves wouldn’t get back to the case through the gravity hole near them.

Instead, the vacuum created by the moving piston would suck the oil into the combustion chamber, where it’ll get burnt with the air-fuel mix from the carburetor.

These will happen every time the engine piston completes a cycle. And as you can imagine, with a generator piston making 3600 moves a minute, the amount of oil getting burnt in one mile can be a lot.

How to Fix a Blown Head Gasket

The blown head gasket has no repairs. The best option is to replace it with a new head gasket. If you have acquired one, then here are the steps to making the replacement:

  • Remove the spark plug.
  • Detach the engine from the generator and set it on a table.
  • Remove the bolts holding the rocker headcover, remove it and set it aside.
  • Now unbolt the cylinder head and set it aside too.
  • The head gasket is the piece sitting between the crankcase and cylinder head.
  • Inspect it for damages. If you see even a crack, replace it with a new piece.
  • Reverse the above steps to reassemble the engine.

6) Clogged Crankcase Vent

An engine or any other engine comes with a crankcase vent, a one-way valve that allows all the gasses build up inside the crankcase to get expelled before causing any issues.

After hours and hours of operation, the vent can get clogged. When that happens, the crankcase gets pressurized. Because of this, the pressure will force the oil to pass through the smallest spaces available to try and fill the void space created by the intake stroke.

The oil in the crankcase will be forced to travel through the rings to the combustion chamber by the internal pressure. And since the pressurization will continue to occur until the vent is unclogged, the engine will continue burning oil unit the low-oil shutdown feature is activated.

How to unclog a crankcase vent

  • Use your generator manual to locate the vent. It’s a PVC-like piece connecting a black rubber tube running from the crankcase to the exhaust.
  • Gently pull out the rubber tube. Using a wrench, detach the vent from the crankcase.
  • Blast it with air from the side connecting to the crankcase to force out any debris stuck in it.
  • Soak it fully in paraffin to clean all the oil stains on it.
  • If nothing is improving, replace it with a new crankcase vent for your generator model.

7) Dirty and Filthy Air Filter

If your generator air filter is clogged with dirt, it won’t allow enough air to reach the carburetor. And since the fuel jet is too small to provide enough fuel to fill the combustion chamber when the piston pulls it, the vacuum effect will pull oil instead of filling the space.

It might be a lot at first, but if the air filter continued to clog, the problem could increase the oil sucking, and the problem can reduce its amount in the crankcase considerably.

How to Fix clogged generator air filter

  • Using your generator manual, locate the air filter (typically covers the carburetor) and unscrew it from the generator.
  • Check for discoloring, dirt, and debris, or oil. If you find any, then you need a new generator air filter.
  • Once you have the new replacement, place it on the cover and screw it to the generator.

8) Your Generator Engine Has Run Its Course

How old is your generator? Usually, the life of a portable generator used for residential backup uses is about 2,000 – 3,000 hours, while that of a diesel generator is 20,000 – 30,000 hours.

If your generator matches these hours, it might be giving up from all the wear and tear. Since the generator piston moves at a speed of 3600 RPM, most of the rotating parts near the combustion chamber are bound to wear out.

When that happens, the oil will start to leak into the chamber, and your generator will be burning too much oil as the problem worsens.

The problem can affect multiple parts, including thinning the cylinder wall, making it wider microscopically, wearing out the rings, blowing out the head gaskets, and damaging the valve.

Unfortunately, fixing all these items at once isn’t feasible; it’d be best to buy a new generator engine for replacement. It will be cheaper than trying to replace them.

9) Too Much Oil in Generator Crankcase

Another way your generator could be burning too much oil and producing too much white or blue smoke is when you flood the crankcase. Usually, you’re supposed to fill your generator oil to the level of the housing threads where the dipsticks sit.

At times, because of the awkwardness of filling the generator oil without a funnel, generator owners are tempted to tilt the unit at an angle. If you check the oil level at this position and return the dipstick, the oil level will be about thrice or triple the required capacity when you set it at a level surface.

That means it’ll be higher than it needs to be, thus creating a puddle that ends at the back end of the engine piston. Instead of the oil splashing onto the piston and cylinder wall, it draws up a lot of oil from the puddle enough to bypass the rings into the combustion chamber.

Once it’s compressed with air-fuel mix and ignited, it will burn and produce smoke, with the amount and density depending on the quantity of oil getting into the combustion chamber.

Related Questions

How Long Does Oil Last in a Generator?

Some generators, especially the new ones, require an oil change after the first 25 hours. After that, you can dump the old oil and refill it with new after 50 to 60 hours, depending on the generator usage and the oil quality. Keep checking the oil for quality; if it’s too dark, then it needs changing.

Can I Leave Oil in My Generator?

Yes, you can. If you’re considering storing your generator, consider checking the oil level before taking it in. Refill if low. Run the generator for a minute to allow the oil to be sprayed on all interior parts.

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Sharif Gen

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