16 HP opposed twin repair, replace, or recycle?

[79TurfTrackRich]

New to the forum, and want to say thanks in advance for your knowledge and expertise! I don't normally work on this kind of thing. I'm a homebuilder and maintenance technician for a real estate company. My mechanical and troubleshooting skills are far above average for things like furnaces, hot water tanks, appliances, etc... however, I have an issue with a lawn tractor that intimidates me.

I have a "sentimental value" lawn tractor that has my 8 year old buttocks engraved on the seat from around 1979 or 1980. I inherited it when my Dad passed a few years ago. It has never seen Ethanol. It ran fine until a couple years ago when it started back firing during shutdown. Then it started to run hot, and sometimes smoking after shut off. Then it just quit. Oil was always checked and changed as needed. Air filter always cleaned. Stored inside and cleaned after use.

It's a B&S 16HP opposed twin.

What are the first thoughts? I put new plugs in it, and positioned the coil. Any friendly guidance is appreciated. I have a smaller lawn and can keep it up well in other ways, but the sentiment of this tractor is important to me, and it still cuts great when it runs. It also pulls a roller or a wagon for projects. I'd love to bring it back to glory. Let me know where to start!

 

[Tiger Small Engine]

New to the forum, and want to say thanks in advance for your knowledge and expertise! I don't normally work on this kind of thing. I'm a homebuilder and maintenance technician for a real estate company. My mechanical and troubleshooting skills are far above average for things like furnaces, hot water tanks, appliances, etc... however, I have an issue with a lawn tractor that intimidates me.

I have a "sentimental value" lawn tractor that has my 8 year old buttocks engraved on the seat from around 1979 or 1980. I inherited it when my Dad passed a few years ago. It has never seen Ethanol. It ran fine until a couple years ago when it started back firing during shutdown. Then it started to run hot, and sometimes smoking after shut off. Then it just quit. Oil was always checked and changed as needed. Air filter always cleaned. Stored inside and cleaned after use.

It's a B&S 16HP opposed twin.

What are the first thoughts? I put new plugs in it, and positioned the coil. Any friendly guidance is appreciated. I have a smaller lawn and can keep it up well in other ways, but the sentiment of this tractor is important to me, and it still cuts great when it runs. It also pulls a roller or a wagon for projects. I'd love to bring it back to glory. Let me know where to start!

The Briggs opposed twin engines are good solid engines. Hard to say what it needs, however, cleaning the carburetor and checking and adjusting the valves would be a good start. Adjusting valves on a non-overhead valve engine like this one involves quite a bit more time and experience. Also check fuel flow to carburetor and fuel for water in it.

 

[Rocky J]

Because you mentioned the coil gap I know you had the fan shroud off and would have seen the mouse nesting and removed it .That would remove the most common reason for heat and smoke . I had a problem like yours ,(exhaust and things close to it smoking, running sloppy ) It ended up being the flywheel key half sheared , flywheel moved about 1/8 inch . Replaced the key and everything was back to running good . If you idle down for a few minutes before turning the key off it might not backfire. As old as that one is it might not have the electric solenoid on the bottom of the carb. This would allow unburnt fuel to continue into the cylinder and be ignited by the carbon on the piston and head area. Idling down for a few minutes lets the carbon cool and hopefully not backfire.

 

[slomo]

Let me know where to start!

Check oil prior to EVERY mow. SAE 30w is your friend.

Guys above are hitting on some good ones. Clean cooling fins yearly on every air cooled small engine, not just mowers. Coil right side up? Solid stream of gas reaching the carb? Spotless fuel tank and fresh lines? Backfiring from carb or muffler?

 

[Craftsman Garage]

I would do whatever you can to fix it up. I've got an opposed twin from 1985 that's still running good, just needs new rings.

 

[Rocky J]

I always like that engine in the vertical series 1 and 2 . The rebuild kits said fits all Briggs Twins . I loved that there was no push rods, rocker arms , rotating cups on top of the valves. One ignition coil , simple charging system .Socket set ,pocket knife and a putty knife and you where Mr. Goodwrench . The Good Old Days .

 

[Auto Doc's]

Sounds like you are motivated to get this thing back up a running good. Motivation will also require patience and attention to detail.

A Briggs and Stratton printed manual would come in handy that covers this series engine. Ebay has them.

This sounds like the priority is the fuel supply system. Start by cleaning the tank and replacing the fuel lines with quality line such as Gates or NAPA.

Locate the numbers stamped into the upper engine shroud so you will have them handy. Most of these have an aluminum plate riveted on the side of the cover with the model, type and serial numbers.

The carburetor kit and other parts are usually available through Ebay, Jack's Small Engine and E-replacement parts.com

Next would be the carburetor. That will take some patience and attention to detail. Just disassemble the main housing components, not every little screw. A rag and a soda flat crate are good to help keep everything accounted for.

A camera on your phone is also handy seeing that you have never done one before. None of the bolts or screws have to be excessively tight, but parts need to be cleaned well and then reassembled in a "snug" fashion.

A small sauce pan with water and a little dawn dish soap on the stove at low heat works wonders for cleaning a carburetor up. Let everything dry well, then spray out all the tiny passages with a good carb spray like CRC Chemtool B-12.

Get it running decent again, then evaluate further for oil leaks or smoking out of the exhaust.

I don't suggest digging into the motor without a mechanic friend to help guide you. Once again, a book is highly recommended.

 

[Forest#2]

Are you now saying that it cranks but does not start?
What do you mean by smoking after it shuts off? (smoking out muffler or what????

Since you are in love and want to keep that engine invest in a Service Manual.
Here is a Service manual for those engines on ebay. Just type this number into the ebay search bar to get an idea of what the SERVICE manual looks like.
196915456845 or 115109056360

My nosing around on-line you might eventually find a free download, pdf

Backfiring on shut down if out the muffler seems to indicate possibly flooding. Those carb's have a big drain plug in the side of the bowl. Remove it and drain the bowl, (the bottom of the bowl will trap water, then prime the carb throat slightly before trying to re-start.
Them are good old engines with just little bit of TLC.
If you get it running you need to remove the air cowling and then use a leaf blower or compressed air and clean the cooling fins. I use a leaf blower almost every time I mow to clean the engine.

Carb kits, pump kits, 3 screw or 4 screw type, $20 Magneto's lots of engine parts still available. Those carbs are easy to work on.
Lots of parts on ebay and Amazon

Here is couple of links for repairing your carb. No need in taking the fuel pump apart yet. The older model pump is the 4 screw pump as shown here. Carbs are basically same just different pumps. When removing the top of the carb the gasket has to come off as the top is removed.
the gasket has to come off as the top is removed.
https://outdoorpowerinfo.com/repairs/

Disassembly, Cleaning and Repair of Briggs and Stratton Opposed Twin-Cylinder Carburetor - Part 1