How do you treat/clean your engines after running them? Or do you?

Thanks Yabby, I consider myself pretty conscientious about caring for my engines, but you have me beat.

I ask the question because I buy well used and abused engines and the stuff that I find left in fuel tanks especially Cox tanked engines to be concerning. I always clean my engines after use but I don't want to go to the trouble to remove that engine and drain the fuel, then screw it on again only to fuel it up again in a couple of weeks. Bad weather moving in and I don't know when I will get to run it again.

Top it off, tooth picks in the vents and leave it for a couple of weeks seems ok.

Thanks - Bob

A couple quick options I would do would be using a filler bulb or syringe attached to the top fill line and suck out whatever fuel you can. I prefer a syringe with a fine needle that fits in teh vent tube so you can get to the very bottom of the tank is my #1 preference. But if not, the fuel bulb will also get most out of it. But this is just me.

Good one Chancey. I have used the bulb before. If you look at some of my photos you can see it in the background. Good for fueling and defueling. Works especially well on stunt tanks where one tube goes all the way to the bottom of the tank. Not so well on standard tanks where you use the needle.. I haven't tried that.

I have also used low volume compressed air <5 psi which works on remote tanks also. But it's messy blowing fuel all over unless you use a cloth to capture it.

Personally, I wouldn't leave fuel in the engine for more than a week. The reed is the least worries. A gummed up reed will un stick itself in short order if it hasn't been run in a little while. It's the plating on the screws and the oxidation on the backplate that forms which causes bigger problems. At first it starts out as dark discoloration on the screws when the plating is compromised and then a mold like fuzz eventually  forms on the potmetal backplate. For the time it takes to either run it or drain it, it makes a lot more sense then letting it sit in there. Static running with the nose pointed up and to the right with a little shake now and then might assist ridding the entire tank while running. When I switched to Sig 1/2A fuel in the 80's, I witnessed cleaner internals in my engines without the need to be so concerned for gumming.

            As far as a remote tank. I've read what others have said. I don't agree with flushing a tank weekly but if it makes one feel good then so be it.  Remove the fuel through the pickup only by holding the plane vertically and to the right. Unfortunately, a properly made control line tank won't have it's pickup tube going entirely to the rear. This can leave a bit of fuel. The only planes I do anything with the tanks is the vintage combat stuff due to not flying them weekly. I put some trans fluid in a syringe and put about a 1/2oz. in the tank  and roll it around storing it with the vents capped. None of this is flushed when going for a restart. Fill the tank, run a tank out on the ground and go fly.

In the past 10 or so years I have used in my RC planes exclusively DIY tanks made of party balloons. I fill it with a 2 oz syringe and defuel it wirh the same syringe through the filling line after the last run to make sure no gummed fuel should stay in the tank.

Balloon tanks are easy to evacuate because they do not have vent lines, and all I have to do is pull strongly on the syringe piston.

Thanks Ken and Andras, you guys probably run more fuel through your engines than most and I was wondering what your precedures were.

As a kid, I never worried about leftover fuel or cleaning my engines. I just left them until the next time which generally wasn't too long and I don't remember having any problems. I don't think I ever disassembled and cleaned an engine back then.

But today! No matter how well you drain an engine or a fuel tank there is always going to be some fuel residue left, especially in the case and/or on the reed. For long term storage the only alternative is a full tear down and after run oil lubrication to avoid a gummed up engine. Ken's observation that a reed will unstick itself with the addition of fresh fuel is a good one. But the rest of it............I have found some severely bound up reedies and FRV engines so my tendencies is after a run out, a spray of RemOil blown out followed by an after run oil and a lot of flipping has worked to keep my engines free after months of inactivity.

Bob, I also don't use castor based fuel. I don't have the issues your having because of it.

Bob, I also don't use castor based fuel. I don't have the issues your having because of it. Today was a real testament to my fuel. My .020 hit the tall grass and somehow the prop came off. The Pee Wee was on a shaft run for nearly 30 or more seconds before I could get to it. I found the prop, screwed it back on and flew the remainder of the day.

The same happened to my TD020, that had a drone prop whose hub exploded mid-air and the engine threw it and screamed unloaded for near 30 sec before I reached the plane. The little beast survived with no apparent damage inflicted. Had it happened with synt oil instead of 20% castor in the fuel, the engine would have wnded up with a lose balljoint or similar, I suppose..

Ken Cook wrote:              Bob, I also don't use castor based fuel. I don't have the issues your having because of it.

Ken, do you run even the COX engines with synt oil only in the fuel? If yes, what is your experience regarding compression and engine longevity?

Contrasting viewpoints re: synthetic and castor between Ken and Andras. Both seemed to survive unloaded runs on 0.20's with each using different lubricants.

After I use up my Cox 25/35% nitro fuels - won't be long as both containers are near empty these will be my options.

Its posible To Find fuel wit As little as 10% or 8% oil all sintec than ad 10% castor I often use fuel for bugy 20% nitro wit 10% oil i ad 10 To 11% castor the litle engine like it I used to abuse them for a cars it's small engine but it's like nothing for them With the experiment that I have done with them until now, no problem

As a precaution - and considering the advice written in all COX engine manuals - I always use all-castor fuels. The only discomfort is the extensive goo discharge, but I would have to wipe my planes after landing even if only half the oil in the fuel is castor..so for me it is worth using all castor lubricant, and it appaently pays back in engine longevity.

I also use all castor in my Cox engines and it has not harmed them. Synth oils are no longer new, but the Cox engine design isnt new either. One of the very best ways to get reliability, performance and long life from an engine is to do it as the manufacturer intended. Getting extra performance..... can often be obtained by a number of simple small things being attended to and maintained properly. Changing the oil type in my view is a very major change to the engine. The only difference between changing oil and machining parts is you can change the oil back if you didnt wreck the engine. Lol. I know this is very very contentious issue, so obviously my view only, and I believe people should consider and give all things a go. But, understand where the issues might be and know how to look for them.

I have had experience in riding and racing extremely high performance two stroke engines and used, Castor, Mineral, and Synth in them. I tried Synth such as Amsoil and Silkolene in my race engines when it became all the rage in bike racing, and not only did people go synth but they were doing stuff like running 50:1 and all started blowing up engines. Eventually they came back to sane oil, fuel ratios using synth and things stopped blowing up.

Oil is very important to performance in more ways than expected, especially in respect to compression, and that is not only compression on the up stroke but critically on the down stroke as that directly impacts the fuel being pushed back up the transfer ports etc. I had the fortune to do tire testing for a day with the Yamaha Factory race team and one of the things the factory engineers were very insistent on was that I raise my oil level to 25% from 20% simply to gain the compression and mainly to increase crankcase compression. That was late 70s - early 80s and engines and oils are much better now and more suited/matched to each others characteristics.

I really think it would take a fair bit to seize a Cox engine. The tolerances just aren't tight enough and the metals used for the pistons and cylinders don't tend to "pick up" very easily which is in some ways an advantage. The Cox engines are bloody tough little engines and I understand the piston joint issue and oil claims, but apart from that they are extremely tough and high performance just used as per manufacturers specifications. My main thought is if you are going to use Synth, use plenty of it. If you want peace of mind, just use castor.

I see it as one of those engine changes where you stand to lose more than you can gain by the change.

Yabby

I could not agree more, Yabby