Here I am

The ol' Briggs & Stratton Diesel

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Does oil have a life span in time?

Should I be getting nervous??

Vaughn MacKenzie

TDR MEMBER
So far this summer I haven't cut a blade of grass using gasoline.



It all started in late February when it was time for the first mow and I found I didn't have enough gas to do the job. I did, however, have a can of diesel which I use for mixing up my fuel additive for easier addition to my fuel tank at fillups.



Hmmmmmm. . . .



I got an evil look in my eye, and proceeded to fill the 22" lawnmower with the oily stuff. I primed the 4. 5hp Briggs and it lit off, puffed a cloud of white smoke and died. After messing around I found that pumping the prime button would keep going and by the time I fumigated the neighborhood it ran under its own power. Amazingly 2-3 minutes after startup the smoke cleared completely and it ran smoothly. Wow. I mowed the lawn and burned up the tank which was about 80% diesel.



That was too easy, I thought, being there was enough gas to ignite with a spark, to make the diesel burn. Time to really put the Briggs to the test!



I thoroughly drained the tank and in went 100% diesel. I took an oil bottle with gas in it and a small hole in the cap to prime the carb with to get it started (this is after it was totally cold). After a few rounds of shooting in the fuel and having it start and die (with a huge cloud of white smoke) I got it going by furiously pushing the button. 2-3 minutes of this and once again the smoke cleared completely and it ran on its own.



Cool! I mowed the lawn again and it ran great. Good power and the tank of fuel lasts longer. When you load it in heavy grass it rattles pretty good and blows some nice-smelling blue smoke, but it doesn't complain too bad. It runs great at any speed between slow idle and full speed.



Shutdowns can be tricky. Hitting the kill switch usually stops it, but sometimes there's enough heat that it diesels away and it really detonates and bangs severely. This is due to the governor making the carb going WOT (something I've gotta tweak before I send a rod through the block). It smokes like a sonofagun for a couple seconds at shutdown.



Spark plugs foul pretty often as you can imagine (every 3-4 tanks) because of the wet fuel at startup. When this happens it still runs but not very smoothly and it backfires violently. Not just a little pop, but a loud BANG!!



I pulled the plug after burning several tanks of diesel and the cylinder is very clean, virtually no carbon buildup. After it has run awhile there are no deposits left on the spark plug.



I've gotten my routine down pretty well now and sometimes I can start it with only 1 quick shot of gas. Hotter weather helps with this too.



Checking the oil and sniffing it is cool, smells just like a diesel. The exhaust smell is very peculair. It smells nothing like a Cummins, PSD, DMax or any other diesel. The odor is a strange concoction of typical lawnmower exhaust and diesel odor. Hard to describe.



I don't recommend trying this at home unless you have a disposable lawnmower with a mechanically sound well-sealed engine. I tried this before on a not-so-fresh Briggs and it couldn't sustain a fire to save its neck!



I guess for those who really have a diesel disease, experiments like this really show how bad I have it!!!



Vaughn
 
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Not Good

I think there is a tie in between this topic and the one about how hot it has been in the tri cities area. Vaughn, you've lost your marbles:) The heat has taken it's toal on your noggin. I recommend you fasten some headlights on that mower and wait till the sun goes down to take care of your yard work:D
 
I was told by a couple of old-timers (before I was one) that they wrapped a piece of copper tubing around the exhaust manifold on an old stovebolt Chevy. Ran diesel through it and in to the carb. They said it ran good but smoked it bit. They said they had to prime it with gas.
 
Which model B & S

Are you using the old flat head or the newer over head valve design?

I know these aircooled engines run very hot and that might contribute to the diesel ignition. I once borrowed a lazer temp guage and pointed it the head on my Yamaha big bear. Read something like 280 degrees f.



Vaughn,you are the stuff geniuses are made out of. Keep up the good work.

Tim
 
someone has posted this type of info before and i have thought about it also, but i wonder if it will work on a 2cycle lawnboy mower?
 
HVAC, hot? Me noggin ith fine! oh, look at all the pretty colors! :p



Skydiver it's the flathead job. But I think you're 100% correct the high temps of an aircooled motor helps the combustion process a lot. I think there's enough heat to almost light off the mixture in the cylinder and the spark plug gets it off. After the engine has run 3-4 minutes and I shut it off, it will start on straight diesel but I have to hit the prime button once. After it is at operating temp I just give the cord a yank and off I go.



tgbol I have a car powered by a 216 Stovebolt 6. It gets the '50 Chevy down the road. Thanks for the great idea!! Heck maybe I will be able to dieselize my whole fleet without trading off all my current vehicles for diesels :rolleyes:



Cat I doubt it would work on a 2-cycle motor, compression would be too weak I am assuming.
 
It would be pretty easy to increase operating engine temps (to help burn the fuel... )...



Just block off a bit of the air intake for the recoil start/engine cooling fan assembly. :)



I tried to run a weed-wacker on Tequila this past weekend... . it didn't run too well..... a quick refill with some 2-stroke ashless mix and it was it's old self again. :-laf



Matt
 
You should try running the weedwacker on some 40% nitromethane / methanol. The weeds won't stand a chance :D Some backwoods white-lightnin also works well in the 'ol B&S lawnmower :cool: A mix of diesel/kerosene will light off better and make for easier starts. :D



Sean
 
I'll suggest that you use a propane torch to evenly heat the head before starting it next time. You might not have to gas prime it or clean the spark plug any more.



Doc
 
I used a 50/50 nitro/methanol in a Briggs once. It got the lawn cut in record time. So we could go to the Antique Swap Meet at Pomona
 
You guys are bad. Nitro in the mower, think I'll try that sometime.



I was thinking about dropping a couple tablespoons of Amonium Nitrate in the tank for a little power boost ;)



Vaughn
 
Hey Vaughn, now it's time to start the bombing on that thing! You could start with a straight exhaust (1/2 x 4" long water pipe will work) and maybe open up the intake!!! I just don't want to hear about any vibration problems at 70 mph... ;)



Scotty
 
Amonium Nitrate

Vaughn, try sprinkling the amonium nitrate powder on your cornflakes in the morning and I predict you will not need ANY fuel for the mower. Just step into the middle of the push bar assembly with your good leg and make like the mower is a hula hoop:D Talk about yur crop circles!:eek:
 
I remember:eek: back when I was a kid:confused: I was going to cut grass. Picked up a can that I thought was gas and filled the tank up. Took forever to get the mower started and boy did it smoke. I picked up the wrong can. My dad had kerosene in that can.
 
What to do next

Now that you got it running on diesel, you need to do what one of the guys here at work does in his car. Stop by the nearest mom & pop diner and offer to haul off their old veg. cooking oil. Take it home, heat it a little bit, then filter it through a screen then a 10 micron filter. Put an aux. tank on your lawnmower with a two way valve, and start your mower on diesel. After it gets going good, switch over to the cooking oil. You may have to heat the fuel line a little bit but it will run and it will make you hungry cause it smells like french fries. Oh, you need to switch back over to deisel before you shut it off. Heck you may be able to run it on gas then switch it over to just cooking oil. On his car, he gets about 1200 miles on a tank of gas. The cooking oils is free. Since you got lots of free time, you probally could make this work. Good luck.
 
It works, well it runs.

I found a new B & S 3. 5 horse on the side of the road in rich folks neighborhood. After about 15 minutes with a hammer the bent crank-shaft was straight enough to run smoothly. Yes it was new,no rust on the muffler,no grass under the deck. This was 3 years ago.



Yesterday,I cranked it on gas got it hot then drained the gas. Even wiped out the tank with a rag. It ran on diesel, but when I tried to mow tall grass and the governor opened up It KNOCKED. I think I'll try 50/50 and see what it does.



Tim
 
Briggs modifications

This is off the subject a bit, but my brother and I made a mini bike a few years ago powered by a Briggs lawnmower engine. We spent several hours fine tuning an exhaust pipe for that thing and when we got done it was unbelievable. When we wound it up down the road it sounded like a big o' Harley! Man, did people ever look - then didn't believe what they saw.
 
What a great idea!



Do 2-stroke engines have a higher compression than 4-strokes?

I 'll bet the higher compression would help to ignite the diesel.



I am building a 12 volt generator with an old Briggs and an internally regulated alternator to charge the batteries on my trailer. I was going to run it off propane but the diesel idea sounds cooler. I have a "garbage picked" 6HP OHV Tecumseh that I haven't tried to start but has good compression when I pull it over. Maybe that one will get a thinner head gasket to raise the compression a few points and more flywheel weight.



To shut it down we should think about cutting off air via the choke or the fuel just like our Cummins. The engine may want to continuing running if you just remove the spark.
 
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