Pitfalls of new old stock small engines? - Honda GX610

I have found a claimed new, never used, Honda GX610K1 engine (18HP) on Facebook Marketplace.

The seller tells me he bought it new and it has sat in the box for minimum of seven years.

He tells me it has never been cranked, and he declined to put gas or oil in it to demonstrate that it runs.

I believe him that it has never been used (based on photos), though I am leery of buying (even a Honda) engine that has sat in a box for almost a decade.

Is this a safe bet, or a situation to sprint away from?

He is asking $750. My thinking is that I could get an extra 5 horses for essentially free if it’s a safe deal, as opposed to buying a new GX390 motor.

My intention is to pair this with an Udor 5.0 MC 18/20-GR pump as a versatile and small-footprint weekend warrior rig.

If it looks new, it probably is… It should be fine… the engine doesn’t know it’s been sitting that long

Has it had oil in the crankcase for the time it’s been sitting up?

He says it is as it came from Honda. So I assume it has had oil in the case the whole time.

This may sound stupid, but no way they would ship an engine dry, right?

They usually don’t come with the operating level of oil in them. There will be some assembly lube from the engine itself being assembled at the factory. If the engine was in a non controlled environment for that amount of time (especially somewhere with higher humidity) without any type of vapor tech product in the crankcase oil, then more than likely some condensation has formed inside the crankcase and there will be some rust. If it was me and a good price for the engine I would buy it and disassemble it to double check everything is good to go. I have seen similar instances where engines have sat up for a long time and a valve was closed and it had enough rust on the seat it bent the pushrod before it freed up. Had to replace the pushrod, which was no biggie but could have been prevented by pulling the valve covers and doing a quick inspection.

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No oil in crankcase? He won’t let you get it running or give you a guarantee? I’d be interested but at a lower price.

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$450 no crank or demonstration. $650 crank and proof.

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Pull the plugs and bump the starter to make sure nothing is seized up. Moisture will cause rust. Oil sitting in it will cause things to swell.

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Maybe it’s not a thing anymore, but we used to put a little squirt of oil in the spark plug holes before starting a dormant motor.

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Yep, marvel mystery oil

It helps to squirt oil in the spark plug holes and then slowly turn the engine over by hand by either turning the flywheel or just turning the key a few times. This will lubricate the rings and cylinder walls since they’re probably bone dry from sitting for so long. If it’s a real old engine and, had a lot of moisture attack it, the rings can rust and seize up. Sometimes disassembly is required sometimes they’ll loosen up on their own. I doubt a brand new 7 year old engine has any issues though. If it does it should be an easy fix.

Thank you guys so much for all the responses.

I have a reasonable offer in. I’m not willing to pay his asking price so I’m hedging the risk a little bit.

If he accepts, I’ll post up my findings on the engine.

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