Briggs 17.5 hp low compression blows oil out vent

vf84pc

Forum Newbie
Joined
Jun 3, 2020
Threads
1
Messages
1
  • / Briggs 17.5 hp low compression blows oil out vent
I have a Ariens 42" (AYP) manuafacture. The mower is in immaculate condition. I rebuilt the Niki carburetor and it runs fine but it blows oil out the vent into the intake. I checked the compression it was about 80psi which is low. Would a bad head gasket cause low compression and depressurize the crank case? Any suggestions would be appreciated.
 

Scrubcadet10

Moderator
Staff member
Joined
Sep 24, 2017
Threads
266
Messages
6,634
  • / Briggs 17.5 hp low compression blows oil out vent
Model number?
Twin? Single? Overhead valve? L head?
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
65
Messages
24,995
  • / Briggs 17.5 hp low compression blows oil out vent
Yes
As will fuel diluted oil
As will too much oil
 

keakar

Well-Known Member
Joined
Apr 28, 2020
Threads
15
Messages
277
  • / Briggs 17.5 hp low compression blows oil out vent
I have a Ariens 42" (AYP) manuafacture. The mower is in immaculate condition. I rebuilt the Niki carburetor and it runs fine but it blows oil out the vent into the intake. I checked the compression it was about 80psi which is low. Would a bad head gasket cause low compression and depressurize the crank case? Any suggestions would be appreciated.
yep, that sounds like the very common blown head gasket issue. its an easy fix if you are mechanical

the head design has a weak point with no bolt on one side because thats where the valve push rods pass through so that where the gasket blows and you start smoking and burn oil and also get oil blowing back into carb
 
Top