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Change the oil in a snowthrower.

Small Engine Maintenance:

Changing Engine Oil
In A Craftsman Snowblower

And Cleaning The Spark Plug...

 

In This Article:

The oil drain plug is removed and the old oil is drained. The plug is replaced and new 5W-30 oil is added. The spark plug is removed, cleaned, and the gap is set to .030".

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Skill Level: 1-2 (Basic) Time Taken: About An Hour

By Bruce W. Maki, Editor

Start:

This Sears Craftsman 28" snowblower needed an oil change. This machine has a 9 HP Tecumseh 4-stroke single-cylinder engine.

Many small engines like this should have the oil changed every 25 hours of operation.

Crafstman 9Hp 28 inch snowblower

FYI: The model number for this 1999 model year snowblower is 247.888530 and the engine is Sears part number 143.999005.

 

Location of oil drain plug. The oil drain plug is at the rear of the engine. There is a piece of galvanized pipe that extends the oil drain for easy access.

 

I used an adjustable wrench to remove the oil drain plug. Removing the oil drain plug.

 

Old oil draining from engine. The oil didn't drain very fast...

 

... so I placed some blocks of 4x4 wood under the front end. Then the oil drained a bit faster. Raising the front to help oil drain.

 

Replacing the oil drain plug. When the oil had drained, I wrapped some Teflon tape around the male threads and installed the drain plug.

 

I tightened the plug with a wrench.

It's important to not over-tighten the drain plug. Since this is a tapered pipe fitting, the rule of thumb is: One to two full turns after the fitting is hand tightened.

Tightening oil drain cap, Sears Craftsman snowthrower.

 

Draining oil catch basin into a calibrated cup.

Then I drained the dish pan into a plastic paint cup that had fluid measurement marks on it.

Since I didn't know how much oil the engine required, I wanted to get an idea of the crankcase capacity.

The old oil filled the cup to the 24 ounce mark.

Here's something that ticks me off: I've NEVER seen a small engine that gave the user ANY idea of the crankcase capacity. This information is usually found in the owner's manual, but what happens if you buy a second-hand lawn mower or snowblower and you don't get the manual?. Why can't small engine manufacturers simply stamp the crankcase capacity on the oil dipstick? Is this too much to ask? I understand that they may use one dipstick design for several different engine designs, but why is it so hard to find this simple information?

I filled another plastic cup to the 24 ounce mark.

I used 5W-30 oil, which is the recommended oil when the operating temperature is below 32 degrees Fahrenheit. Above that temperature, SAE 30 weight oil should be used.

Snowblower engine oil: 5W-30.

 

Adding oil to snowthrowerr engine. I placed a long skinny funnel in the oil fill tube... but I couldn't rest the plastic cup in this funnel, so I placed another larger funnel inside the orange one...

 

... so I could rest the plastic cup in the funnel and let it drain for a few minutes.

 

Checking oil on Tecumseh 9HP engine.

I check the oil level. It was right at the FULL mark, so my measurement of 24 ounces was accurate.

This concluded the oil change procedure.

 

The other maintenance procedures for small 4-stroke engines are: 1) cleaning and checking the gap on the spark plug, and 2) cleaning the air filter.

Removing And Cleaning The Spark Plug:

Removing spark plug wire on Tecumseh engine, Craftsman snowblower. I grabbed the spark plug wire and pulled firmly to disconnect it from the spark plug terminal.

 

Then I used a 13/16" spark plug socket and ratchet to loosen the spark plug. Removing spark plug on 9HP Tecumseh engine in Craftsman snowthrower.

 

Removing spark plug from small engine. I unscrewed the spark plug and carefully lifted it from the hole, making sure that I didn't knock any dirt into the spark plug hole.

 

This is the spark plug after I removed it.

This plug is still in good condition. How can I tell?

  • The center electrode (round center part) is not worn away.
  • The insulator (the white donut-shaped part around the electrode) is intact and not overly dirty.
  • The ground electrode is not worn away.

Since there was not a lot of carbon deposits on the spark plug, I can tell that the engine is running properly and that the air-fuel ratio is neither too rich (which will leave more carbon) or too lean (which will overheat the spark plug and wear away the metal electrodes).

Spark plug after removal.

 

Spark plug gap measurement. The owner's manual says that the spark plug gap should be .030 inches.

 

I used a spark plug gap tool to check the plug gap. The .030 wire fit inside the gap with a slight amount of drag, which is ideal.

If there wasn't any drag on the tool, I would've needed to close the gap slightly. My method for reducing the spark plug gap is to tap the ground electrode on something hard and heavy, like the flat part of my bench vise or the concrete floor.

See below for procedure on opening the spark plug gap.

Checking spark plug gap.

 

Spark plug gap tool. This is a common spark plug gap tool. The wide flat "T"-shaped parts are used to bend the ground electrode and open the gap.

 

Increasing The Spark Plug Gap:

The gap tool is inserted around the ground electrode like this, and the tool is tilted away to bend the electrode upwards.

This tool can also be used to close the gap, but I just tap the on the ground electrode to bend it inward, as mentioned earlier.

Adjusting spark plug gap.

 

Cleaning black carbon deposits on spark plug.

Cleaning The Carbon Deposits:

I folded a small piece of emery cloth (about 400 grit, I think) and inserted the cloth into the spark plug gap. Then I just slid the emery cloth back and forth a few times to remove the soot.

I also rubbed the cloth on the outer areas of the ground electrode, the metal rim, and anywhere else I could reach.

 

When done, the spark plug looked a little cleaner. It doesn't need to be perfect. Cleaned spark plug.

 

Anti-seize compound on spark plug threads.

Before installing the spark plug I applied a small dab of copper-based anti-seize compound to the threads.

It's important to only use a very small amount of this product. In fact, I wiped off some of this before installing the plug.

I learned from my auto mechanics training was that the only suitable lubricant for spark plug threads is a copper-based lubricant. This step isn't necessary, but it should help prevent the spark plug threads from seizing up if the engine ever gets too hot.

After checking the spark plug, I would've cleaned the air filter... but I couldn't find it. It turns out... snowblowers don't need air filters. I suppose a snowblower doesn't have a problem with dust getting into the air intake since there usually isn't much dust floating in the air in the wintertime.

More Info:

Tools Used:

  • Adjustable Wrench
  • Spark Plug Socket - 13/16"
  • Ratchet
  • Plastic Dish Pan
  • Quart-size Paint Cups (2)

Materials Used:

  • Motor Oil, 5W-30
  • Emery Cloth

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© Copyright 2007 Maki Media Group LLC

Written December 29, 2007