Small Engines (Lawn Mowers, etc.)/Gas in the crank case


Eric, I have gas in the crank case of a 28q777 Briggs engine. I have read extensively on how this happens, primarily through carb float issues. Rather than mess with a rebuild, I bought a new carb. The tractor started, I ran it for say 5 minutes and it died.  Guess what? I have gas in my crank case yet again. I was wondering about a bad head gasket but cannot readily find an on line link between my issue and the head gasket. Is there one?
I checked my compression... 70psi... I pulled the head. I have some minor scoring of the cylinder walls. The head gasket was intact but I can see a probable head gasket compromise between the cylinder and valve rod cavity. Tomorrow I plan on replacing the gasket, setting the torque on the heads and giving it a try. I will also attempt to adjust the valves ( I understand the principals but I have never done this before so wish me luck)
Can you tell me if I am on the right path? I assume that a new Oem carb is plug and play with no float issues...
Can a compromised head gasket cause my issue?
Any idea's on what else could be causing the draining gas in to my crank case?
I appreciate your time!

A bad head gasket does not usually cause gas to enter the oil.  The problem is almost always a leaking carburetor.

There are special tools to verify if the carburetor is holding 4-5 psi, as it should, to stop the flow of gas.  

Did you search You Tube for how to pressure test a lawn mower carburetor?


Small Engines (Lawn Mowers, etc.)

All Answers

Answers by Expert:

Ask Experts


Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

©2017 All rights reserved.