616 Engine Troubles - excessive oil leakage, etc

[mikesdak]

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.

 

[mechanic mark]

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

 

[bertsmobile1]

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.

 

[mikesdak]

Numbers: 303447 1222E1 00060111

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