Troy-Bolt Engine rebuild or replace

I have a 30 year old Troy-bilt horse tiller with a 8hp Kohler Magnum, the engine is fouling plugs and using oil. The question is the Kohler worth rebuilding or do I buy a new engine.

The smart thing to do is to rebuild the Kohler. It lasted 30 years. That alone should tell you what a great engine it is. Rebuild kits are available on e-Bay. Find a machine shop that is experienced in
rebuilding Kohler K and M engines. Do it right and get another 30 years of service.

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Tom is correct about the quality and dependability of the Kohler but "worth it?" That depends on how much of the work you can preform yourself. If you have to hire out the rebuild and speaking in terms of money only you would be dollar foolish to rebuild the Kohler. Using the aftermarket kit mentioned, plus other parts that should be included in a total rebuild such as valve guide work, carb kit, governor gear and then adding for machine work and labor you could very easily stick $500-700 in that 8HP Magnum. I have personally seen bills MUCH higher than that when shop does all the work. If that doesn't bother you go for it. Around here you can buy a Troy horse with very little use and in excellent operating condition for that kind of money every day of the week. Sell your smoker complete for $350 and you get my drift,,, Other options are to is repower, the Chinese Honda clones are popular for this and for good reason, they are cheap and dependable. It is also possible that a set of rings and touching up the valves will get it by for quite a few years but personally I am not into half arsed engine "rebuilds". Another option is to hire the machine work but do everything else yourself. Kohler's manuals are the best (and free) with step by step tear down, inspection and back together. If you can follow instructions you can do it.

All that being said I personally would rebuild the Kohler. Because its a quality unit and I can do it all in house for the cost of the parts.

One thing that has not been discussed is balance and weight. Kohler M Series engines are made of cast iron and use a very heavy flywheel. Your Kohler may weigh twice as much as an aluminum Honda clone engine. So depending on the style of tiller you have, using a lightweight engine may affect the balance and performance of the tiller. Front-tine models are notorious for bouncing around. Rear-tine models use the engine weight to offset the tine area weight when you have to lift the tiller up at the end of a run and quickly do a 180 for the next pass.

When Troy-Built engineered your tiller, they did so in full recognition of the engine weight. This too.... is something you may wish to ponder while deciding on a course of action.

This is a great point to bring up. That Kohler is heavy. It helps keep that machine from taking off when you hit a tough spot and balances it out. I have a Horse with a repower and the neighbor has one purchased new with the Kohler. There is no comparison between the two machines. Wait until winter and rebuild the Kohler.

The weight issue question raised is valid but Troy had several optional engines for that model tiller years ago including an aluminum block Tecumseh. The new ones all have aluminum block lightweight engines.

For consideration is a link to small engine warehouse and engines that will bolt in the Troy Horse tiller, quite a few of them are attractive alternatives to sticking a bunch of money in the Kohler M8.

As I said, rebuilding the M8 is how I would go but a guy who has to hire it done better be ready for sticker shock.
Troy Bilt Horse replacement engines

I agree with the others about rebuilding the M8 - the kit for a new rod, piston, rings and gasket kit can be had for $75. The machine shop work should be around $60 - $80. I don't know if the valves are the same between an M8 and a K181. If not then there might be the deciding factor - they can be salvaged or replaced.


Otherwise I replaced the old Tecumseh HH60 on mine with a Predator engine from Harbor Freight for $99. Direct bolt in only now the throttle controls are on the engine instead of the handles. I hadn't realized how down on power the Tecumseh was until the new engine fired up.

(reply to post at 09:12:07 06/08/16)

Click to expand...

I sold the 6hp Tecumseh engine for $65.00. No problems with
my 10 hp B&S. Hal