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Hello.

I have a briggs vanguard 16HP OHV horizontal shaft, in a 2002 grasshopper mower. I have owned it for 5 years. I would estimate it has somewhere around 1000 hours. I think it is model no. 303447. It has been leaking a fair amount of oil for about two years. I don't note any smoke, so I suspect it is just leakage.

In 2013, I replaced the flywheel end crankshaft seal, which was protruding from its recess. It had leaked around the seal for quite a while, as the shroud was very oily. After replacing the seal, it has still gone thru a lot of oil due to leakage. Oil drips are visible on the fins when running. Lots of oil on the shroud surrounding the cylinder.

Last summer, I did a bit of diagnostics. There is positive pressure on the oil dipstick tube: At about 2000 RPM, it coated my hand with oil within a few seconds. I did a compression test: left cylinder - 100# Right Cylinder = 120#



Last night, I noticed one loose head bolt on the left cylinder. I retightened this to see if it would cure the compression imbalance, without pulling the head. I haven't retested the pressures yet.

I also noted leakage around the dipstick fill tube. I can't see what type of dipstick seal is supposed to be present. All I see is a slight bevel on the aluminum block surrounding the tube. The tube pulled out easily when I was working on the head. I think dipstick tube is this model: New Briggs Oil Filler Tube 690897 | eBay Any idea about the seal for this type of fill tube?


Can anyone show me a picture of the dipstick tube seal area on the block? I don't know how this is supposed to look.

Anyone have similar experiences or thoughts on the oil leakage and compression imbalance? Head gasket?

I haven't pulled the breather yet, maybe that is part of the problem as well. There is a fair amount of oil entering the air cleaner from the breather tube, but this might be an effect of something else....


Any thoughts and experiences would be greatly appreciated.

Post complete list of numbers from engine data plate, thanks. What brand & weight oil are you using?

Dip stick tube will pump. that is normal.
Dip stick tube has a seal that should be replaced periodically.
Without checking I think it is the standard B & S screw in grommet.
Breather has a reed / flapper valve that needs to be cleaned occasionally as they do gum up and allow excessive pressure to build up inside the engine
When installing oil seals to the crank I wrap the shaft in glad wrap then put some vasalene on both the seal tip and the glad wrap because the threads & / or key ways can easily damage the sealing tip of the oil seal.
If I come across one that has popped I always install the replacement with some loctite if there is no signs of excessive oil blow by.

On the down side, the 20% difference between the cylinders indicated a problem and needs further investigation.
Could be a leaking head gasket pressurising the crankcase more than the breather can cope with.

Numbers: 303447 1222E1 00060111

I use 30 wt conventional oil, to try to slow the rate of loss.....