Mower blowing White smoke

This video walks you through the diagnoses & repair process step by step, including: checking oil level and removing excessive oil the easy way, checking compression, fitting a new carburetor.

Over View

You’ll find useful resources on this page, tips, links to tools, parts and supplies required to complete your repair.

White smoke is the drama queen of mower problems, sure it looks serious, but it rarely is. The smoke is caused by oil mixing with gas in the combustion chamber. As the oil burns it bellows white smoke.

Excessive oil in the cylinder is usually caused by:

  1. Tilting mower to the wrong side
  2. Overfilling oil level
  3. Faulty carburetor float needle
  4. Blown head-gasket
  5. Engine rings worn

Before working on your mower be sure to remove the plug wire to prevent accidental starting, see “Repair Safety Video”.

Resources

Briggs & Stratton – Most models take from empty .65 US quarts (.6 lts) 5W30 engine oil.

Honda engines – Most take from empty .58 US quarts (.55 lts) of 10W30 engine oil.

Kawasaki engines – Most take from empty .6 US quarts (.6 lts) 10W30 engine oil.

Kohler engines – Most take from empty .6 US quarts (.6 lts) 10W30 engine oil.

For exact specs see:

Briggs & Stratton spec

Honda spec

Kawasaki spec

Kohler spec

Tools & Parts

To nail this procedure you may need some of the following tools, parts and supplies.


WD40

This is first on the list for good reason, Wd solves a ton of problems. I won't work without it, because I can't. Picture links to Amazon.com

Ratchet Tool Set

Before we can do anything, we'll need tools. I've selected this set as I own some Craftsman tools and while I have worn some out, they did do a lot of work. So I expect this set will last the occasional user quite a long time.

This set carries both metric and standard sockets and that's important, because some mowers will have both type of fastener sizes. Set includes spark plug sockets. Picture links to Amazon.com


Gas & Oil Syphon

You'll find this tool really useful if you need to drain the gas tank, and you will if the gas is stale. The siphon will remove it without fuss or mess and it can be used for extracting the oil too. Picture links to Amazon.com

Gas Line Clamp

Some small engines will have a gas tap, which is really handy when removing the carburetor, stops gas flowing all over the shop. However most engines won't have one, these useful clamps simply squeeze the fuel line and prevent a spill while you perform surgery. Picture links to Amazon.com

Carb Cleaner

When cleaning your carburetor you'll need this stuff. Gumming is a sticky substance that's hard to shift. The carb cleaner will remove it, however if your carb is really bad, save yourself some work, go ahead and buy a new carburetor. Picture links to Amazon.com

Cleaners

You'll find these nylon brushes super useful when it comes time to clean those tiny passageways of the carburetor and jet. Use these in conjunction with the WD Carb cleaner. Picture links to Amazon.com

Gas Stabilizer

Mix this with the gas when winterizing your small engine. Gas isn't what it used to be, it goes stale, in some cases after just one month. Bad gas causes gumming and that's a carburetor killer. Stabilizer will save you money and stress in the long run. Picture links to Amazon.com

Gas Can

Briggs and Stratton refuel can. These guys got it right, I like it a lot, it offers press button control, no fuss no mess and no funnel required. Picture links to Amazon.com

Compression Tester

This is a compression tester, it's fitted in the plug hole using the adaptor. The engine is cranked over and a reading of how much compression the cylinder makes is captured on the gauge.

A low reading can be caused by a simple fault such as a sticking valve. Picture links to Amazon.com


Leak-down Tester

The OTc is quality kit and will last many years of use. A leak-down tester will require compressed air. The tester measures how much air escapes a cylinder and helps you find weak rings, valves head gaskets etc. Picture links to Amazon.com

Briggs & Stratton

This is a popular Hooai Carburettor fitted to walk behind mowers with Quantum engines, but check the engine codes listed. This is an Auto choke carburettor.

This carburettor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue. Picture links to Amazon.com


Briggs & Stratton

This is a after market replacement carburettor for the Briggs 4-7hp engines. This is the primer bulb style carburettor.

This carburettor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue.

It comes with a replacement air filter/primer bulb housing gasket. Without this gasket your primer bulb won't work. Picture links to Amazon.com


Briggs & Stratton

This is an original Briggs carburettor fitted to walk behind mowers. Part # 593261, these guy's are made from plastic and I see lots of issues with them. The jet holes are particularly tiny and block so easily. There are a few different types and all look alike, so use part numbers to check before ordering. Picture links to Amazon.com

Briggs & Stratton

This is a popular carburettor fitted to the classic range of Briggs and Stratton engines. This engine is fitted to many different walk behind lawn mower mower models like, MTD, TORO, Murray, Poulan, Craftsman and many more. Picture links to Amazon.com

Honda GCV 160

This is a Hooai carburettor fitted to the Honda GCV160 engine only, not the GVC190. It comes with gaskets, plug, filter and fuel line.

Fitting isn't difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com


Honda GCV 190

This is a Hipa GCV 190 carburettor fitted to the Honda GCV190 engine only, not the GVC160. It comes with gaskets, plug, filter and fuel line.

Fitting isn't difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com

Auto Technician and Writer at | Website

John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.