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Hello all! I've been working on lawn mowers for neighbors and family since "mastering" the flathead briggs (or so I thought), and recently came across one that was seized solid. It was bad honestly, because it appears as though the aluminum piston melted a bit and the wall too. The rings seized in the piston too, and upon disassembly the oil wiper ring (middle one) broke. I decided that I would just try to fix it as cheap as possible, as I've known these Briggs engines to survive pretty much all abuse. I just sanded the piston skirt a bit to get some melted metal looking extrusions smoothed off, and the walls were lightly sanded to remove extrusions. I don't have the means to bore the engine or hone it, and from what I understand it doesn't work well in aluminum bores anyway. I kid you not, knowing that the wiper ring mostly only wipes extra oil off the walls (as far as I know anyway) I decided to rebuild it and test it before buying new rings. This thing fired right up like new and cuts grass. Seems to have good enough compression to chew thick grass. I don't know how honestly, but I thought it would be salvageable after that. Only flaw is that it SPEWS blue smoke. No knocking or anything. Even after I put a few divots in the piston head from banging it un-seized. Obviously this is likely mostly because of my ring missing, and maybe because the rings are still tight in one spot because of the piston damage and the scoring. Ordered new rings and they're the wrong size so I'm sending them back, but the it occurred to me that the damage to the walls might mean new rings wouldn't seat properly and the engine wouldn't ever stop smoking. At least, not unless I overbored it and got oversized rings, but again I don't really have the means to do that. I'm 16 :laughing: I'm hoping if I sand a bit of material off the piston ring gaps in the piston to make the rings not so tight, and then put new rings in and maybe add some engine restore to the oil (sounds gimmicky, but I've seen it work wonders on youtube project farm channel and hes trustworthy). That it will work again. Walls not having hatching isn't good, but the scores themselves hold oil I guess haha.

Anyway, I just wanted somebody's opinion as to how likely it is new rings would set and the engine would run well enough/retain enough oil to be used like once a week for 3 months a year over like 5 years. Nothing heavy.

Let me know what y'all think. Thanks!

Without the cylinder walls being smooth and the bore being round getting rings to seat, and not fog the local mosquito population will be about impossible. But those old L head engines would take a lot of abuse sometimes. If you want to play around with it as see what happens it may be a good learning experience. Worse case situation the engine goes boom. Either way it will be a learning experience. I learned to work on lawnmower engines basically doing the same types of things you are thinking about.

Lots of disagreement about this but the oil we have available today is not good for the aluminum bore and piston friction, do some oil research and look for barrier lubrication. But you can look around on Ebay for a while and find a stock bore size chrome ring set that is good for a stock rebuild. Find these rings pretty cheap sometimes. These little motors are fun to work on I think. Not out much if you screw it up anyway.

tom3 said:

Lots of disagreement about this but the oil we have available today is not good for the aluminum bore and piston friction, do some oil research and look for barrier lubrication. But you can look around on Ebay for a while and find a stock bore size chrome ring set that is good for a stock rebuild. Find these rings pretty cheap sometimes. These little motors are fun to work on I think. Not out much if you screw it up anyway.

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Thanks for the reply. Is what you're saying meaning that our oil is not meant for these engines, and I should look for barrier lubrication type oil (royal purple?) instead?. If so I'll look into getting some oil of that type. I am aware that these engines are weaker because of the aluminum bores vs iron, but some are supposed to be coated (still not as good) I don't know if this one is coated at all, as it is Briggs low end engine... but if it isn't I assume boring/honing is viable. I just don't know how to get necessary tools and measure out .1 inches, etc.

Also, Are chrome rings better on worn engines? Do they seat better in engines with scoring or something? If so I'll look for a set. I don't want to invest a ton of money in this, but if I get tools I can reuse on other engines (I have probably 10 Briggs engines laying around) then it's no big deal.

Thanks again!

ILENGINE said:

Without the cylinder walls being smooth and the bore being round getting rings to seat, and not fog the local mosquito population will be about impossible. But those old L head engines would take a lot of abuse sometimes. If you want to play around with it as see what happens it may be a good learning experience. Worse case situation the engine goes boom. Either way it will be a learning experience. I learned to work on lawnmower engines basically doing the same types of things you are thinking about.

Click to expand...

I think I might try to see what happens with new rings... maybe it will be acceptable enough to use for a few years and add a 1/4 quart every once in a while. It does not knock and actually sounds healthy when running. If memory serves me correctly right now, the crank case ventilation seemed normal too. Not excessive blow by. So maybe the smoke in the exhaust is just from oil not being wiped by the ring. Odd because it smokes a ton, not a little, but so much you start coughing. It actually fouled a plug after 3 minutes one time. If rings don't fix it, then I'll just save my rings for another less toasted engine and slap one of my spare 3.5 briggs on there. Not as powerful as the 6.5, but I've never seen the 3.5 briggs struggle with normal homeowner grass. Makes me wonder why they're bigger now... As long as I can find a way to put the brake and maybe self propel on the older briggs, I don't see why it wouldn't work.