Briggs 18 hp Horizontal Opposed Twin Knock

[HondaG100]

Model 422437 Type 0678 01 Code 84032912. Mounted in a Grasshopper 1822. This is my personal mower. I rebuilt the engine 3 years ago. Bought the mower cheap because it burned more oil than gas. It has mowed my yard for 3 seasons now with less trouble than most equipment that is 20 years newer. First time out this year it ran as usual but idling afterward I heard a single sharp knock followed immediately by running on one cylinder only. I expected the engine to immediately install a new and very large crankcase breather hole but it didn't. Instead it started running normally again only to repeat the sequence over again a few seconds later. This ONLY happens at idle. At any other speed it runs perfectly. Compression check showed 80 and nothing the first time. A later check showed 80 and 90. Gotta love intermittent problems. Valve train looks normal at a glance and the rods look ok from what I can see through the valve oiler hole. The engine is going to be torn down but I am still curious if some of the older techs here have seen this problem and what it ended being?

[StarTech]

Easy to check the internals on this engine, just pull the crankcase access panel cover. The only is gaining access to this panel as every one I seen has it install to the rear toward the operator station.

It can about anything piston or valve related. Usually a sudden loss compression is a broken rod but yours came back to life so it maybe a valve problem.

As for tearing down I would just removing the head on the side that loss compression and crankcase access panel first for inspection. Even with burning oil it can a valve guide, rings, or cylinder wear problems.

Let us know how things goes.

[bgsengine]

It is an L-Head, aluminum block, I am going to make a bet that you will find a loose valve seat.

[Deere2me]

It is an L-Head, aluminum block, I am going to make a bet that you will find a loose valve seat.

More than likely.

[Walt 2002]

[quote="Starfire1"]Easy to check the internals on this engine, just pull the crankcase access panel cover. The only is gaining access to this panel as every one I seen has it install to the rear toward the operator station.

Might want to rethink that. Model number indicates this is a horizontal shaft engine.

Walt Conner

[StarTech]

Easy to check the internals on this engine, just pull the crankcase access panel cover. The only is gaining access to this panel as every one I seen has it install to the rear toward the operator station.

Might want to rethink that. Model number indicates this is a horizontal shaft engine.

Walt Conner

Thanks Walt for bringing that to my attention, I had two customers knocking on the door before I even open the doors this morning and I should had seen it was a horizontal engine.

For initial troubleshooting then I would only pull the head on the cylinder in question.

Sorry HondaG100 for the mis-information; my fault there. Should had that second cup of Java before typing.

[HondaG100]

Thanks guys. With any luck I will get it pulled apart this weekend and will post what I find.

[madmantrapper]

I have one of those horizontal opposed, it has well over two thousand hours on it maybe close to three. It came of a craftsman mower I bought in about 1985. Had 1800 hours on it when I removed it,the mower and frame finally rooted out, this was in 2003 or 4. I rigged the engine and transaxile up on a buggy for my youngest son to drive around the neighborhood. This engine has been used for numerous things, even drove a log splitter for awhile. We had it on a drilling rig driving a hydraulic pump for years while we were trying to find perks to develop some otherwise useless property. That thing is a work horse for sure. I still have it and am thinks of putting it back on a buggy for a seven year old little girl that lives with us. This thing sure don't owe us anything.

[HondaG100]

It is an L-Head, aluminum block, I am going to make a bet that you will find a loose valve seat.

Right on BGS and Deere! Beer is on me. Number 1 exhaust valve seat pulled out by hand. The exhaust valves both looked like they run hot. Almost white. It does not run hot or lean so maybe I have an issue with loose exhaust seats not transferring heat correctly? Oversize seats the solution here?

[Walt 2002]

Depends on whether the block is wallowed out around the seat. IF not, they can be peened back in, I can send you a Service Manual including the procedure IF you like. Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com