Jake, this is one of your best videos yet (that I have watched)! I've got a B&S mower engine coated with dirty oil, low/black oil inside, carboned up spark plug, etc. and suspected it was a clogged PCV system somewhere. This video came up in my feed after searching and watching several others and is, by far, the best of them all. I really appreciate how you took the time and care to illustrate with examples in other machines so all relevant details and causes were covered. As always, great production qualities. I learned several things I didn't know before, most significantly the circular self-destructive issue of worn rings blowby ultimately resulting in air filter blockage, subsequent over-rich condition further intensifying oil vapors to carb. I'm hoping to have a leakdown tester setup soon so I can do more efficient diagnostics into issues like this beforehand in order to determine if it's actually blowby or a clogged PCV system or whatever. I know that I can run an engine and look for smoke coming out of the dipstick tube, which indicates blown head gasket but it would be nice to really determine the ultimate cause before I start addressing the issue. (Hope that makes sense!) ;-) Thanks once again for a great video!
The extra fuel washes the oil off the rings causing even more ring wear and a recipe for even more aggravated oil spray coming from the breather. I am convinced I ruined the reeds in my vent system by overfilling with a quart of oil in my first mower. I always cared for the filter. Changed the oil but after 7 years I had enough. It would basically choke and foul on it's own oil. No rod knocking if I recall. I believe rings and or the breather valve failed. Wish I had tried this 20 years ago. It does help to get by.
Cool. I did this today to a PowerSmart mower I found in the trash. I made a little breather for the crankcase hose with a small bottle and filter foam. It quit fouling plugs and mowed my whole yard after cleaning the carb. I think it's engine blow-by but it improved after an hour and 2 oil changes.
Thanks for another great video! I have to replace the clutch cable on my Craftsman lawn tractor. Already have the cable and it looks easy enough to do! I try to do what I can myself.
Excellent video. I basically did the same crankcase breather delete mod exactly as you describe to solve a no restart when hot problem on a 725EXI OHV Briggs. It completely eliminated the problem. But it didn’t address the root cause of really excessive blowby which I’m hoping is just a blown head gasket which I’m going to be changing ASAP. Apparently the hot no restart was being caused by the hot oil fumes messing up the fuel air mix to the point the engine would not start until the engine cooled off enough, usually after about 20 minutes. Rerouting the breather off the carburetor is at best a temporary means to keep an engine going but eventually you will need to address the root cause of the blowby. My 725EXI is smoking very badly and still running strong but it’s oil consumption is very high and i am tired of coming in from a lawn mowing session with my clothes reeking of oil fumes!
Jake, Great video. I have a 2010 TroyBilt TB146EC I inherited in 2014. Previous owner and I both garaged and cleaned the machine after use so the external condition is fantastic. Probably less than 250 total hours on the machine because the applications were light garden cultivating around the homes. However, I'm not certain how meticulous the previous owner was about following the instructions to fill the crankcase oil. I'm not certain if the breather hose for this is anything special other than a preformed hose or if it has a pressure restrictor inside that could be blown from overpressure. I'm going to try your oil breather bypass, and try to install an accumulator for the blown oil. Then, it also looks like the piston and/or piston ring assemblies are still available for between $32 or $62 respectively. Again, thanks for the lesson. Jeff
I've had to double and triple up on those gaskets. One time I used 3 washers that were just a bit bigger than the 3 Briggs bolt heads inside the air box. That seemed to work.
Nice fix buddy, your customer must be extremely happy since they have an aluminium deck they may get much more than two years use out of the old mower. Do you think it would help if you used a Lucas 20% oil additive or even Restore which i have heard even helps build up compression as seen on Project Farm?
It's possible a thicker oil would help, but we have to remember that theres a negative pressure (suction) in the air box, and a positive pressure at the breather tube, so by routing the breather to the atmosphere, it will greatly decrease the vacuum effect, and should lower oil consumption!
I was given a old snapper. Did your bearings video fix. Works great. Then the engine went bonkers. Oil was full of gas. Oil in air filter. I ain't doing the rings. Time maybe to find a engine.
Just a update on that Snapper. Put this n new breather passage gasket. And cleaned the valve cover so that little diaphragm would move....problem stopped.
I would have installed that engine with the exhaust pointing forward just to save on the ears and avoid the exhaust fumes. He probably gets a whopping headache if he uses it for an hour
Hi, i have a little Yard King 4 stroke 24.5cc and i realized the valves are all one part with the cylinder SO is there a path for the pressure to go up into the valve area past the rods and out through that hose there as they also have another hose and nipple on side just under piston area which sends out lot of oily goo into the air cleaner then it goes up a tube and gets sucked into the carb and burnt. Makes the carb throat a little dirty perhaps. So 2 hoses going to Air Cleaner. question- If the gases from crankcase cant get up to the top out through that top hose i HAVE to have that oily hose breathing going to A/Cleaner and CANT Block it off? or crankcase gases will explode seals? So other option is maybe connect a fuel filter to end and let it take all the crap and change it but it would also allow backflow back into CC?. so no good? Any ideas.. thanks?
I keep all used plugs and ultra sonic clean them Just to give them away to folks who can’t buy new mower and to keep worn out ones running Mainly old folks like Me
ok but i broke the metal breather tube off at the crank case on a 4.5 briggs my only concern is its under the flywheel cover and right by the muffler i dont really care about the machine i pulled it out of my neighbors garbage so if i just JB weld it back in place would that be enough?
I'm gonna try this, great video. Just curious, would it be worth it to replace the worn piston rings if that is what's causing the problem? I have a 6.75 190cc Briggs and Stratton Gold series mower that still cuts good but is burning some oil. It was given to me by someone who never changed the oil or cleaned the air filter. I just replaced the head gasket, and when I did, the valves were coated with carbon. I cleaned everything up, but I did notice some tiny scoring in the piston cylinder. When I mowed today, it ran great, but every once in a while, some smoke would come out of the muffler, so something still ain't right. I assume the cylinder and rings are worn, but since it is still cutting good, I want to hang onto it if I can. Thanks.
For the work required, you can probably find a newer engine on a mower that has a rotten deck on craigslist (kijiji here in Canada) and just swap it over. I see carbon buildup on many engines, completely normal. It's burning a bit of oil here and there, probably rings like you said. Then again, cylinder could be out of round, then you need to bore, and oversize piston and rings. Just think of the work required, compared to the cost for swapping one for another. I don't rebuild engines here at my shop, usually just repower for the cost. Thanks for watching!
@@EliminatorPerformance - Yep, seems like a lot of work. Just trying to keep it going. I'll look online for a new engine when the mower isn't worth the trouble of fixing anymore. Thanks for the quick reply.
@@EliminatorPerformance - Hey, just wanted to say that your tip worked great, no oil in filter. Thanks. I did notice that smoky-type puffs were now coming out from that breather tube instead of the muffler at times, but not as much, and there was no oil to wipe up. Still, the engine is burning oil, it was low by the time I finished. The mower runs great, but it does seem hot, maybe too hot to the point the oil is burning and not dripping. I saw a Donyboy73 video where he talked about bad valve seats/guides that can cause burning oil, do you think that could be the problem here? The last time I took it apart to replace the head gasket, the valves had sludge all over them, with the exhaust valve actually looking burnt near the top. I cleaned it up like new, and the valves seemed to fit flush on their seats, but the guides at the rear did seem sorta loose. This was my first time doing this, so I'm a novice. I wish you were local, the people here want to charge $75 just to look at it.
@@Nick23at63 yes, worn valve guides usually cause oil into the combustion chamber, but only usually when the engine is cold. Once it heats up, the metal expands and it stops burning oil. Sounds to me like you're getting increased blow-by through the piston rings and have excess crankcase pressure.
@@EliminatorPerformance - Thanks. Just checking, since replacing valve guides would be much cheaper than a piston repair, which I have already ruled out. One last question, I see where you can buy replacement valves, but other than a broken valve, couldn't the valve just be cleaned, or do they lose shape from heat?
Big brother e. P a Same issues with automobiles. I make "catch cans" that capture the oil, but allow the vapors to be recycled as intended. Just have to empty it now and then. Gov is happy, engine is happy.
The engine creates pressure that needs to vent, negative and positive. If you block it, oil will be forced out of the oil seals, and you'll most likely blow a gasket, or gaskets.
I picked up an old briggs sprint mower and oil is coming out of the breather tube. I was thinking to attach a flexible tube to the breather tube and face it upwards to prevent the oil coming out. Would this work?
