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Buying used engines

Old 02-12-2019, 01:17 AM
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Twinhydro
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Exclamation Buying used engines



I have bought a few used glow engines on the for sale Marketplace here and have been disappointed . The last purchase was a Super Tiger 90 Glow listed in good condition . The engine I received was very hard to turn over and the bearings were very " notchy " feeling . I took off the engine backplate and head only to find a lot of rust from the engine sitting for a long time with fuel residue . Although the standard practice in RC boat racing circles , after run oil does not seem to be a regular practice in the airplane crowd . I have been flying and boat racing since 1980 so over that time I have had dozens and dozens of different engines and installed and replaces many many bearing due to use and neglect . Lube the engines up if you are not going to use them , glow fuel is very corrosive and will hurt the bearings if left to sit .. I will have to rebuild the engine I just got from Marketplace . Buyer Beware !

Last edited by Twinhydro; 02-12-2019 at 02:38 AM.
Old 02-12-2019, 02:59 AM
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Hobbsy
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Not so much rust but castor residue and that's exactly what I expect an engine to look like when I receive it.. Most of the time I order the Boca Bearings before I get the engine. I just received this Saito 182 and it looks great and is great, no cam or lifter wear, rocker arm tips not worn. But when I pulled the cylinders and the cams off, the rear bearing was notchy as you described. I had a new rear bearing and am waiting on a new front bearing from Boca.
Old 02-12-2019, 04:56 AM
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Twinhydro
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Sorry that you set your expectations so low Hobbsy ! The photo does not do it justice . When I buy a used engine in "good " condition I expect to at least be able to use it .
Old 02-12-2019, 05:32 AM
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Jesse Open
 
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The little castor residue I usually see is quite easily cleaned (only when absolutely needed). On the other hand,rust from water absorbed synthetic slime is a most unwelcomed sight.
Old 02-12-2019, 07:17 AM
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Hobbsy
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Synthetic slime is non existent, a figment of your imagination.

My definition of low expectation is called reality. Needing bearings is a non issue to me.
Old 02-12-2019, 07:27 AM
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Jesse Open
 
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My imagination could never be that good. Seen the SLIME all too often. Not alone there.
Needing bearings isn't a "problem". Anybody can replace parts.
Old 02-12-2019, 08:04 AM
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Twin hydro, I think what you are seeing in your engine is not rust but congealed castor oil. Old castor is often confused for rust. When I buy used engines I always figure a new set of bearings in the price of the engine. My latest buy, a YS 160DZ also needs a camshaft from a botched disassembly. It felt like it needed new bearings and the exhaust port was very clean. At the time a steal at $150. I'll still come out OK in the end I think.

Buying used can sometimes be a crap shoot. Over all I know I am money ahead. In your case, throw in a set of bearings along with a good cleaning and I'll bet you have a good engine there.

Ken
Old 02-12-2019, 10:40 AM
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Twinhydro
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Guys , it's rust from corrosion , I know what I'm looking at and have had scores of model engines over the years and have dozens currently . All I'm saying is that they should be represented properly ie " needs bearings " , "feels rough " etc . At that point you make a choice to buy or not .
Old 02-12-2019, 11:13 AM
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(if it works) click on my link, then click on photo to enlarge the photo,,
rather rust or not there is debris in that engine, before taking it completely apart I would remove Back Plate, Carb and head and soak it in hot antifeeze, every 2 hours turn the crank, when done clean off the antifreeze with WD, then rinse with rubbing alcohol, once dried add a few drops of oil and turn it over, go from there

just my $0.02 than may be worth $40


https://cimg3.ibsrv.net/gimg/www.rcu...6ef516331d.jpg

Jim

Last edited by the Wasp; 02-12-2019 at 11:15 AM.
Old 02-12-2019, 11:22 AM
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Jesse Open
 
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Not sure where you fly but around here, ARO is used far more often than not. Very common anong the aircraft modelers here. I generally avoid the boat and car folks so can't speak for them.
I however did not suggest what you were seeing is not rust, just that I prefer to see a bit of varnish over the typical rust issues.
Two rules, 1. Don't sweat the small stuff, 2. It's all small stuff.
Old 02-12-2019, 03:37 PM
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Twinhydro
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Thanks for all the replies . I really don't need any help building engines as I have been building all kinds from motorcycles with 4 valve per cylinder 15,000 rpm engines , countless HP 2 stroke motorcycles and High Performance outboards and MX engines and hundreds of RC engines , but I do appreciate the feedback . The post was directed at the manner in which engines are represented as in "good " condition . In the RC boat racing world when you rep an engine as good you get a photo like this . posted . granted , marine engines are much more expensive and operate at much higher RPM than most aircraft engines except pylon racers . Rep the engine truthfully is all I ask and is all anyone can expect .
Notice ... NO RUST or BS inside the engine , this is the way it should be .

Last edited by Twinhydro; 02-12-2019 at 03:40 PM.
Old 02-12-2019, 05:40 PM
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This is rust.
It's only like that because it's your engine, loved and cared for, other people can screw up a brick.

Last edited by Hobbsy; 02-12-2019 at 06:02 PM.
Old 02-12-2019, 07:30 PM
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I think most people are honest in their description of an engine for sale. Some simply don’t know the condition of what they’re selling. I once bought an O.S. 61 fsr that was advertised to turn over smooth. When I received it, it turned over smoothly alright but when I took off the rear cover I discovered the main bearing was seized and the crankshaft was rotating inside of it. I returned that engine!
Old 02-13-2019, 01:22 AM
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Twinhydro
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Originally Posted by Hobbsy


This is rust.
It's only like that because it's your engine, loved and cared for, other people can screw up a brick.
Actually not mine but one for sale on International Waters .
Old 02-13-2019, 03:26 AM
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One must consider the fuels used for different “venues” of operation. Airplanes are operated in relatively dry environments as are cars. As such, fuels have different lube and additive packages in them. Boats are a different animal and as such, fuels for them are formulated a bit differently for a number of reasons. This is the main reason why you will see differing conditions internally when ARO isn’t used and the engine is stored a long time. I don’t use ARO for short term storage, but 1 year or more gets a healthy dose of oil. I’m not picky on what I use - sewing machine oil or ATF works splendid for me. The engine I have pictured has 3-4 gallons of 15% nitro 20% oil (70/30 blend of castor/Klotz respectively) fuel through it with zero after run oil used. Still turns freely and smoothly. End of day operation and storage regimens will have differing results. The most important thing IMO is getting the fuel residue (and moisture byproducts) OUT ASAP. Acids are formed when synthetic PAG oils break down in the presence of water, and add to the fact methanol gets more corrosive being moisture laden, and so on and so forth.... Its not rocket science, but does require a little bit of forethought to maintain model engines.

Last edited by 1QwkSport2.5r; 02-13-2019 at 03:30 AM.
Old 02-13-2019, 03:32 AM
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That clean case with castor oiled fuel must be a figment of your imagination
Old 02-13-2019, 05:50 AM
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Originally Posted by Jesse Open
That clean case with castor oiled fuel must be a figment of your imagination
It must be. .

Old 02-13-2019, 11:54 AM
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when you buy used you take your chances, that is why I never pay top dollar for a used engine.
Old 02-13-2019, 01:48 PM
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I always assume a used ball raced engine will need new bearings. Probably 90% of the used engines I’ve gotten have needed them. I do test run the engine first before replacing the bearings just to make sure. Sometimes a couple tanks of fuel on the bench clears them out and they turn smooth. Most of the time they need to be replaced though.
Old 02-13-2019, 03:48 PM
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Twinhydro
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Originally Posted by 1QwkSport2.5r
I always assume a used ball raced engine will need new bearings. Probably 90% of the used engines I’ve gotten have needed them. I do test run the engine first before replacing the bearings just to make sure. Sometimes a couple tanks of fuel on the bench clears them out and they turn smooth. Most of the time they need to be replaced though.
I have gotten lucky with many engines in the past . The seller has offered a refund but I may just fix it . All good replies , thanks . Not that I was looking to agree with everyone as I'm always up for a good debate ( argument ! ) . I do feel it was a good topic to bring to the forefront as it is somewhat ambiguous at times .Thanks .
Old 02-14-2019, 03:24 AM
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I sold one engine to a friend based only on the description that I got from the fellow who sold it to me. Turned out it did need bearings. I was totally embarassed and offered a refund outright.
I will NEVER sell an engine again without a complete inspection, even a brand new, old stock engine. Good chance, I won't sell or trade engines for the most part. Easier to just give them away locally.
Old 02-14-2019, 04:09 AM
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Hobbsy
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I don't hold it against a guy when I buy an engine that needs bearings, as Tim stated 90% of used engine need them. I'd get far more upset by pliers marks but you'd see them in the images, usually.
Old 02-14-2019, 06:25 AM
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Jesse Open
 
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I'm with you on pliers marks! That and hubs scarred by puller jaws. Another is over size mounting holes.

Chipped fins and stripped or fractured exhaust ports .....

Sand or abrasive blasted engines go right back to the seller.
Old 02-14-2019, 10:30 AM
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Originally Posted by Jesse Open
I sold one engine to a friend based only on the description that I got from the fellow who sold it to me. Turned out it did need bearings. I was totally embarassed and offered a refund outright.
I will NEVER sell an engine again without a complete inspection, even a brand new, old stock engine. Good chance, I won't sell or trade engines for the most part. Easier to just give them away locally.
I bought an used engine once that needed bearings like you say,, the seller got it from some one else, if you been in the hobby as long as I have and if you know engines well enough you really can't blame the seller much at all, considering he offered to buy it back and pay the the shipping too, you see I had an OS Hyper 50 Heli engine that had less than 1 gallon run threw it, and it's rear bearing rust up badly after setting for just one winter..

Easier to just give them away locally
Gary, any time you get the urge to give away a Saito 91, 90T or 100T you just let me know, if it's worth rebuilding I just may be happy to send money your way LOL

Jim
Old 02-19-2019, 03:06 AM
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Twinhydro
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Few more pics , got it apart .

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