Seized piston engines can run again but not for long? What do you think?

[06mourag]

I always had lots of olds chainsaws and 2 stroke engines and my dad use to say to me that a siezed engine will not run again unless you put a new piston and rebore or replate the cylinder.
But in last few months i have been trying to rebuild some siezed engines that i had from farmers that forgot ro mix 2 stroke with normal fuel so the engine more likely seized
what i have done is:
carefully slided the cylinder out and horned it
got some sandpaper and carefully sanded the piston to get the rings out because they where covered in alluminium form the piston and they would not seal
sanded the rings until there where no marks all around
sanded the piston until it looked like new and perfectelly around with no marks
but everything back together with oil to ensure good lube in the dried bearings/rings (cleaned with lots of 2 stroke mix before)
then i pulled the cord and it had as much compression as brand new!!!
then i put some 2 stroke mix in the tank and chain oil
pulled the start cord hard with the choke on and it started 2 pull(also rebuilded the carb!) and it still runs perfect after 2 full tanks of fuel and lots of hours on it!
SO I THINK EVERY ENGINES DESERVES TO LIVE NO MATTER WHAT ! (they just need a bit of love and care!)
but my dad says that is not going to run for long!
what do you think???

[Jeff Haulman]

I don't see why it wouldn't run along time. Time will tell.

Opinions vary but if it isnt seriously rusted, pitted, damaged, welded stuck (lack of oil) i dont see why not. I've recovered a hand full of 2 cycles like that and or simular too that. Still run too this day.

[Pioneer620]

Well, if you got things cleaned up properly and compression is good, I don't see why they wouldn't run for long. It all depends on the damge that was done to them. It would help prolong their lives if you run a little extra oil in the mix though. I tend to run the mix a bit heavy, even if it does end up fouling the plug a little. To me, that's a little better than a scored piston.

[Steve Kunz]

I had a weedeater that I let someone borrow and you guessed it they put regular gas in it. They ran it until it locked up. I took the plug out and soaked the cylinder with penetrating oil, and finally got it to turn over. It seemed like it ran better than ever after that. I used it for years until the rest of it wore out, but it still ran good.
Steve

[Pioneer620]

wow, a damned good weedeater

[Andrew Mackey]

I have worked on many 2 and 4 cycle engines that have seized and ran again! Quite a few loosened up when they cooled off, Put 16:1 mix in them, and they ran good! I had a customer bring in a Sears blower. Her son ran a full tank of straight gas in it before it died. It was locked up tighter that tricky dicks hatband! I put kerosene in the cylinder, left it to sit overnight, and the next morning, gave the starter a yank for the hell of it. man was I surprised when it pulled over!. I put some SAE 30 in the carb and the cylinder, and pulled it over some more. Fresh 16:1 with SAE 30 non detergent oil, a couple of yanks, and the machine fired up and ran pretty good. It continued to run another 3 years before a second dose of straight gas did it in. This time, melted aluminum was visible in the muffler, without taking it off the machine!

A shop I used to work for when I was a kid, used to free up stuck engines all the time. If after freeing up, they didn't smoke too bad, they were returned to service! The engines were used on MOPECO heater blower units, used to blow and heat fresh air into manholes for Public Service Utility. The operators almost never checked the oil on their equipment, and every piece of equipment I worked on for them had seized at one time or another! We sold more Kohler pistons than I could count! More often than not, the heads were pulled, and kerosene was poured on top of the puston. We has a special oak block turned to fit the cylinder within .020" of the cylinder diameter. The block was placed on top of the piston, and given a sharp rap with a 2 pound maul. If the piston came loose within a couple whacks, and at bottom Dead center there was no aluminum transfer on the cylinder, the engine was flushed out with kerosene, fresh oil put in the case, and the engine would be test run. If it was quiet (no rod rap), it was returned to service. Heavy smoke, rod rap, or aluminum in the cylinder meant engine overhaul, usually a honing, new piston and con rod, and a gasket set had the engine running just fine. Occasionally, we would find the crank blued by the overheated bearing. The aluminum would be scraped off the crank, the journal polished with 1,000 grit crocus cloth, and the engine would be re-assembled, none the worse for wear!

B&S engines, seized, were an easy fix. Flush out the crankcase with kerosene to remove any debris. Remove the spark plug. Add a mix of 1 pint kerosene and 1 pint SAE 30 oil to the crankcase, turn the unit upside down and let it sit 24 hours. Next day, turn the unit upright, remove the starter cover, and put a flat jaw monkey wrench on the starter pawl, and turn the engine over. Usually the engine would turn, hard at first, but would loosen up in short order. The starter would be re-installed, the spark plug re-installed, and then the engine would be started and run for about 10 minutes with the kero-oil mix in the case! The oil/kero mix was then drained, the crankcase filled to the proper level with SAE 30, and the unit test run again for 1/2 an hour, at full load. If it ran good, and didn't smoke too bad, $75 Please, and off you go! Some B&S engines would lock up 2 or 3 times before they would blow up, usually because they were again run out of oil! If the engines smoked too bad, they were replaced.
Andrew

[reh1119]

I have un stuck engines before using marvel mistory oil that stuff does wonders

[Rene Elliott]

If there was no cylinder damage or burnt out bearings I see no problems, it shouldn't take long to figure out if there are any.

[bill chasser]

I have done that many times to saws pulled out of the scrap pile and never had a lick of trouble with them. Hard to cull out a $900 saw when it could be saved for a few dollars, brake clean, emory cloth and a ring groove cleaner

[davey1000]

When I was young I had a Maicoletta (a huge motor-scooter with a 250cc two stroke engine) The pistons would sometimes seize but with a little practice the head and barrel could be removed in less than an hour. The pistons were Mahle aluminium-silicon alloy and black marks would appear on the piston skirt. These marks were very hard and needed to be filed off as otherwise they would wear the cylinder. In the Maico Owners Club it was reckoned that pistons weren't run-in (broken-in) properly until they had seized three times. After that they were really good and the machines would do eighty miles per hour (or more!) There is no need to condemn an engine just because it has seized. Usually a little fettling will restore it to good health.

[thefonz6752]

Most of the 2-cycle engines had a very thin chrome plating in the cylinder. If not too bad the aluuminum could be removed from the chrome without much harm to the cylinder. If one happened to hone through the chrome the engine would not last long.
Jerry

[Johnnyboy]

Dont you need to take into consideration that the cylinder is chromed or not, I have been told that if the cylinder is chromed that you can not hone it! I have been using Seafoam to unstick engines with amazing results!

[bigGURN]

My only concern would be if the piston was sloppy in the bore from sanding. I have freed up a good many engines over the years and any repeat seized engines where because the bore-piston fit was too sloppy.

[SoTexRattler]

When a teenager, my family bought a brand new lawnboy 2-stroke mower. The old spring-start Sears clunker finally died... (thankfully)
I kept 2-stroke mix for the new mower in an old scraped-up Coleman fuel can.
I was away for some reason and my mom insisted on mowing. She found the coleman fuel can, but this one had COLEMAN FUEL IN IT!!!
It ran quite a lot longer than I ever expected before it locked-up tight.
I got home that weekend and poured straight 2-stroke mix into the sparkplug hole and turned it on its side. I grabbed the mower blade and gave it a good twist. It unlocked and with each successive turn it got easier and easier..

That old lawnboy ran another 11 years with no apparent ill effects.

[Adirondackstihl]

Personally I would have replaced the piston and rings. Cleaning a cylinder with muriatic acid and sandpaper is common.

[mcbob]

Depends a lot on what the piston is like wether the piston to bore clearance is too great after you clean the piston and cylinder of unwanted metal transfer.

McBob.

[Toesmack]

I have resurrected plenty of snowmobiles and dirt bikes and reused pistons that have encountered mild to moderate siezures. Having good results in engines that spin up in excess of 9,000 rpm has given me a great sense of accomplishment. Muriatic acid is indeed an excellent way to remove aluminum from the cylinder wall, but caution is the key here. If the cylinder is a coated (nikasil lined) aluminum assembly, you want to apply the acid with a Q-tip and rinse with water after a few minutes, then reapply. If left too long it will burn thru the nikasil.

As for the pistons, moderate scoring can be cleaned and pistons reused provided you can restore a smooth surface. Ring grooves need to be sharp and clean, but the skirt is far less critical. Be very certain your crank bearings are free of contamination, ANY debris will lead to failure. Unless they rotate completely smooth, failure is just around the corner.

Budget is always a consideration, New parts can be expensive or even unavaliable, if you can fix it for less, why not?