Good morning and welcome to SMHRB, where we put aside politics for a few and look around us, at our homes and surroundings, to see if we can fix or better them. Our intrepid band of amateurs and pros volunteer to share their accumulated knowledge and experience to answer your questions, steer you along the right path, and show you how you, too, can do-it-yourself. I'm CodeTalker and I'll be your host today.
Today I'd like to introduce you to one of my new Fixit Projects - a 1985 era MTD brand 8HP lawn tractor/mower. I received it as a thank you for helping some friends recently, and hope it will replace my previous Murray 12HP lawn tractor, a much larger one that had a serious problem with a really stupid cob-job weld someone did years ago on the cutting deck bearings that left the dual grass cutting blades at different heights and with a serious vibration, and me too concerned about the danger it posed to use it or want to fix it. The smaller mower is much more suited to our 1/4 acre lot, IF I can get it back in service; it apparently hasn't been run in years and was filthy, frankly, but not rusty or worn out as far as I can tell, so I have hope that it will all work out.
Follow me over the KosKurl and I'll let you in on how I approach such a thing.
Many times I've been asked to fix gas engine powered machines, both 2-stroke and 4-stroke, including a riding mower that was built in the 40's. Typically, someone acquires such a machine from someone who doesn't want it anymore, either because it doesn't work right, or just plain doesn't work. The new owner then tries to get the machine "running" - which usually consists of trying to start the engine, hoping to thereby determine if the machine is worth "fixing." I'm here to tell you, that's exactly the WRONG way to go about it, and explain why.
An engine is a beautiful piece of machinery, among them my favorite, the typical Briggs & Stratton 4-stroke design of the last 70 years. I've even worked on several that are almost that old and still running quite well, as well as dozens of late models. They are well designed and built like a tank, typically heavy cast iron based and very solid, and made to give many years of service if cared for properly. More modern small engines are variations of those designs, of course - lighter and more complicated, to be sure; but older B&S 4-strokers were made to last, simple, and probably could run forever if not abused, IMHO. (Nothing against other brands, I just prefer B&S)
So why is trying to determine if an engine will run the wrong step to take when looking to use an old machine? Because that's the very thing that can destroy it! I can't remember how many times someone has brought me a chain saw, a string trimmer, a mower, or a tractor that they tried to put gas into and attempted to start - and got exactly nowhere. Or made them worse. Or worse yet, ruined a perfectly good engine to the point where it needed to be rebuilt, or even (sigh!) junked.
Okay, so how SHOULD you approach such a machine? My take is pretty straightforward; 1st: (and most important!) CLEAN IT and look it over carefully - for cracks or obvious problems that would be a deal-breaker. Didn't find any? Good, then do this 2nd: get make/model/serial number and any other info off it, and the machine it runs, anything that you can find (write it down, take pictures, make records!), and 3rd: go do your homework. Forget gas and/or oil at this stage - it's too early in the process to think about them yet. You need to first know what you have, how to service it, and the right steps to take before you can try to run it!
This latest rider of mine is typical - I went online to determine the actual MAKER of the "Hechinger" branded mower (Hechinger is a former building/garden supply chain here in the East that went under 20 or so years ago, IIRC), which proved it's an MTD (and the year it was built, via the serial number), and then I went looking to see if any parts are still available (some are, most - probably not). Many machine manufacturers have pretty good websites, where you can find out all you need to know, and even download owner manuals (or even the coveted Shop or Repair Manuals!), parts diagrams, and parts lists. (I bought a CD once that covers parts and repairs for all Homelite chain saw models for the last 30 years on eBay - handy when I own 2 and have another one in for sharpening and tuneup!)
I was able to find everything I need except the exact owners manual for my tractor, but was also able to come up with manuals for others in the same series which are close enough that I can use them for my refurbish purposes. Be persistent, LOOK carefully at the material you find, make sure it shows what you actually have, even if it has a different model number - many machines didn't change much between model years, for example. Google is your best friend here; don't forget to try partial model numbers if you can't find the exact one you have.
Then, I went after the engine info - after all, if I can't properly set up that engine the mower won't be any good at all. Tracking down B&S engines is a textbook example of good record-keeping by a company; you can find nearly EVERY exact engine that B&S made by model and serial number, plus get the diagrams, lists and manuals that go with it, and locate original or replacement parts from them or one of their legion of retail affiliates. With minimal effort, I obtained maintenance info, starting and operating info, fuel and oil requirements, exploded parts drawings, etc., and all for free.
Armed with all this new knowledge about my 8HP engine, I've already checked it for major faults (it has none), then serviced, charged, and tested the 12V battery for the electric starter, cleaned the engine thoroughly, and started to pull the carb for service; then I'm going to check for hidden damage like cracks or leaks (even though it means removing part of the mower body to get at it better), drain the old oil, refill with proper new oil, setup the electrical wiring with good grounds and tight connections, service or replace the spark plug, clean and pre-adjust the carb, clean and re-oil the air filter foam, take care of all linkage, make sure everything is moving properly (and within specs if I can check them), check for spark, watch closely for oil leaks, make sure it spins freely without a plug in, change the fuel filter, and then - ONLY THEN - add gas before I turn it over to see if it will start and run.
Now, you might be thinking, I'm putting a lot of work into an engine BEFORE I even know if it's worth it, and before finding out if it will run, but trust me; if you don't, and you just try to fire it up without prepping it first, you'll hurt it, screw it up, make it worse, or even ruin it! I've seen a bunch of screwed up 2-strokes, for example, that guys got their hands on and just tried to throw some mix in and start - some even ran for a few seconds (and one was right out of the box!) before they died, all because they didn't take the time to read up on how to treat their tool BEFORE starting it.
A brand new trimmer was brought to me that ran "just fine" for about 30 seconds - when it died AND seized, because the new owner had NO idea that he was supposed to mix the gas and oil! I had to disassemble a BRAND NEW ENGINE to get it working again, and it took all my ingenuity to free the piston without damaging it further. (Been running fine for several years now, thank you...) And I'd love to have a buck for every engine someone found that had some "leftover" gas in, but the tool "won't start no matter what I do", or they dumped someone's pre-mix in, only to find out it was too strong, or even worse, not strong enough, or they got it started and just HAD to twist the speed screw, or tried to adjust the idle screw without specs and it wouldn't restart, or - well, you get the idea.
TIPS: READ and follow 2-stroke mix directions EXACTLY for best results, all gas goes "bad" in a few months unless you use Stabil, plus gas with 10-20% ethanol can ruin some engines so check before using it! Also, a lot of chain saws take a stronger mix like 40:1, while smaller engines like trimmers may take only a 50:1 mix - you can't swap them, and you really need to know what mix the tool calls for! Plus, most lawn mowers and a lot of small engines CANNOT use automotive oils - a lot of them use straight, non-detergent SAE/30 oil - you need to know which is which. Also, there are ways to tell if you have a good spark without testers, ways to know if your spark timing is off, cheap rebuild kits for most carburetors that aren't hard to do yourself, and recommended settings for idle screws and such that will help get your engine running long enough to do a proper adjustment.
So my point is, this ain't rocket science, folks. I learned a lot about engines from books before we had computers, and a lot from a guy who had fixed them for many years - but you can too. There's information enough out there to cover virtually ANY engine you get your hands on, new OR used, and EVERY engine you try should get cared for BEFORE you fire it up, not AFTER. The difference may well be whether you get a short time of life, or a lifetime of use. I'll keep you posted on my progress with the 8HP rider project - I'm not in a rush because if I can't find some critical parts I'll get rid of it, and if I decide it's worth keeping it'll be because I gave it a once-over-under-and-through proper prep before trying to get it running. Is it worth it in the end? You tell me - it's almost winter 2013-2014, I'm still using my Dad's old snowblower from the 60's, it still starts on the 1st or 2nd try, it works great even in heavy snow, and it was..... wait for it.... free except for tuneup parts, gas, and oil. Now THAT'S a bargain!
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