Burning oil, Tear Down Time.

[ESully]

I have a 19 year old Craftsman 42" Lawn Tractor with a Briggs & Stratton Model 407777 Type 0167E1 Code 020311YG engine.
It has done well over the years, but oil usage tells me it's time to open it up. I'm thinking it will need at least a new set of rings, but of course I won't know for sure till I open it up.
Currently it has about 160 psi compression on both cyclinders. It tends to run ok if I keep the oil at the low mark on the dip stick, but if I bring it above that oil usage goes up quite a bit.
I have rebuilt a few car and motorcycle engines over the years, but never a lawn mower engine. I was wondering if anyone could guide me on where to find torque specs and a good source for parts. Also if anyone has a link for a good rebuild link or video.
Thanks, Ed

 

[bertsmobile1]

Service manuals for B & S engines are all over the web
Broken down into side valve or OHV & Single or twin so get the right one for your engine
At worst you can buy used manuals on evilpay or craigs List .
If you have done a motorcycle then you can do a mower.
Only real trick is the con rod can only go in one way or it will foul on the case.
If your engine has a counterweight then always replace the bolt that holds the halves together

 

[slomo]

Are the valves set proper? 160 psi sounds like the head is full of carbon or the valves are really loose??

What oil are you using?

Pull the head/s and decarbon the head and valves.

Clean the cooling fins while you are at it.

 

[ESully]

I'm sure there is carbon buildup, which is why I think it is time for new rings.
I use Rotella 30wt.

 

[ESully]

I finally finished using the mower for the season, so it was time for a tear-down. I removed the majority of gunk from the engine, with a little further clean up to go. Before I pulled it, I added BG engine cleaner to the oil and some Wurth intake cleaner through the carburetor throats. Prior to this, the plugs were carboned up enough for one cylinder to quit. Internals look very nice after 19 years of 1 1/2 hours a week, with a good patch of carbon on the pistons. Intake valve was great, exhaust had some minor build up. I forgot to take pictures of heads before I went home. The cylinder walls are nice and shiny with some crosshatch still left, reflecting the piston top nicely.
I was planning to hone the cylinders and new rings, along with lapping the valves and new seals on the intake valves.

 

[ESully]

I finally had a bit of warm weather last week and gave the mower a break in run. After a nice run I drained the oil. It was of course quite dirty from assembly lube and ring seating.
I gave it fresh oil and this week used it for an hour with the trailer hauling debris from my spring yard cleanup. The new rings and valve guide seals seem to have worked. It's running great, no oil burning, and the oil looks clean. I'll pull the valve covers soon and check the valve clearances, but overall I'm very happy with how it turned out.

 

[sgkent]

the clean areas on the edge of the piston are caused by oil washing over the rings. If the carbon was all the way to the piston edge it would not be coming by the rings. The detergents in the oil dissolve the carbon. That is one way we could always determine where oil was coming from as we took engines apart to machine them. That piston photo shows that a lot of oil has been coming by the rings.

 

[bertsmobile1]

the clean areas on the edge of the piston are caused by oil washing over the rings. If the carbon was all the way to the piston edge it would not be coming by the rings. The detergents in the oil dissolve the carbon. That is one way we could always determine where oil was coming from as we took engines apart to machine them. That piston photo shows that a lot of oil has been coming by the rings.

DETERGENTS DO NOT DISSOLVE ANYTHING
Never have
Never will
DETERGENTS Carry away foreign particles and prevent them joining together to form a sludge
Some of the really sofisticated ones will allow a small number of foreign particles to join till it gets to a particular size to make filtering more efficient .
SOLVENTS dissolve which is why they are called SOLVENTS
Unfortunately the fluid under the sink is mislabeled as detergent and it cleans your dishes so to the drug addled brain ( or what was left of it ) of an advertising agency creative if washing u detergent cleans his cocain impliments then a detergent oil must clean your engine .
From then on it sank into peoples minds and stayed there with all the other trash like a dewatering solution is the same as a penetrating fluid
A detergent is a dispersant of sorts although on a molecular level they work slightly differently .

 

[sgkent]

I worked for a guy who built among others, Al Unser Jr's winning engines. He also built winning FI engines and Indy engines. The oil washing over the piston tops container additives that the oil industry calls "detergents" as in a generic term, that wash the carbon away. That is a fact. I don't wish to argue with you but if you insist go pick on someone else.

 

[Rivets]

The detergents that are put in oil to hold contaminants in suspension until they can be removed from the engine. As Bert said they are not cleaners. In a properly tuned engine the amount of carbon above the piston head should be negligible as the extremely small of oil which is not scrapped down by the oil ring is burned away during normal operation. If you really want to get picky, carbon is a solid which there is not known solvent for. The detergent holds it in suspension until you change the oil. What most people call carbon in a cylinder is really oil in a non fluid state, which can be dissolved with a solvent.