Buying used engines
#1
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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.
#2
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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.
#4
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.
#6
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.
Needing bearings isn't a "problem". Anybody can replace parts.
#7
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
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
#8
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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 .
#9
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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
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.
#10
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.
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.
#11
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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.
#13
My Feedback: (12)
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!
#15
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.
#19
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.
#20
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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.
#21
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 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.
#22
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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.
#23
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.
Chipped fins and stripped or fractured exhaust ports .....
Sand or abrasive blasted engines go right back to the seller.
#24
My Feedback: (1)
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 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.
Easier to just give them away locally
Jim