Well, this isint exactly a beginner question but I am posting here for the benefit of anyone else with the problem.

Last week I broke-in and flew a OS FS110A on a Reactor Bipe. Having not touched the airplane all week, I took it out yesterday to fit the cowl. Then I found it had no compression whatsoever. After much breaking my head over what could be wrong, I opened the valve cover and found that the cam pushrod for the suction valve that goes to the tappet was no longer connected under the tappet. Further, when the crank was turned, it wouldnt move either. That prompted a complete engine disassembly, my first on a 4c. I found that the cam follower for the same valve was stuck in the engine casting. A firm tap with a nose plier handle and it dropped into the cam case and I was able to take it out. I found it had a dark circle of rust all around. The exhaust side follower was also rusted in the same place but less so. Also the crank part that meshes with the cam gear was very dark brown in colour. Dont know what I could have done with the crank, but I lightly polished the followers with sandpaper and the rust band was gone. Then simply oiled and reinstalled everything and now the engine has a LOT more compression. In fact its so tight, I can only just about turn the prop over compression by hand. Is there some issue with this engine and has anyone com across such a problem before?

Ameyam

Are you sure it was rust and not burned castor oil? Burned castor is brown in color and will look a lot like rust, but comes off fairly easy with an abrasive. Either way no, it's not common to have a rust or burned castor problem with a new engine like that. At the same time, a little too much heat from too lean a break in run can cause the latter, while not pre-oiling the valvetrain before running the engine can cause the former.

It could be burned castor also. The patch was reddish brown and cleaned off very easily. Its not due to a lean run in though, I kept it thoroughly rich, slobberingly rich in fact

I ran the engine today again. It now seems to have a lot more power. But also a lot more compression. During the rebuild I had to take the rocker assembly off to take the head off. While re-assembling, I just put it back in, I havent moved anything. Thats is why the much higher compression now as compared to before concerns me. Couldnt verify it though coz first time my glow driver had discharged and second time my starter battery discharged to the point I could stop the starter chuck rotating with my hand. With the cowl fitted, I cant put my finger over the carb to choke it. The alternative method of closing the exhaust to choke it cant be done with me both holding the airplane and applying the starter. I will try tomorrow with a friend and my lead acid battery is charging as we speak

Ameyam

Amey, with what you get for fuel in India I would guess you have an oil problem more then a rust problem as Jester stated. I don't have a new OS on hand and haven't worked on the 110 yet so really know nothing about that engine. The .91 and older 1.20s I have worked on a lot.
To give you an idea of how bad an oil problem can be, I had my favorite YS 1.10 in a new plane just a couple months ago. When I went to start it there was zero compression? When I opened the rocker arm cover I discovered the exhaust valve was stuck open. I could pull it closed but that was very hard. That made me think the valve stem was gunked up and sticking. I pulled the valve and cleaned it up, it really wasn't that bad and when I was testing the fit it would still stick? Seems the valve guide was full of old hardened oil? I had to use the paper stem of a Q-Tip and steel wool attached to a drill to remove the built up crud.
The reason for this crud was the fuel I use started using less oil so I was adding 2 ounces of Klotz blended oil to every gallon of fuel. That has 20% Castor oil in the blend. I had pulled this engine and stored it for almost a year and that Castor dried up and was keeping the valve from moving.
Something as simple as that can cause a huge problem. Now I am just adding 1 ounce of Red Line full synthetic two stroke oil to my fuel, no more Castor.
The oil problem just came up from a guy here on RCU that is in India at the moment, he has been having problems locating any of the good name brands of anything there and with what he is able to find is having no end of trouble with his engines.
I tried soaking my engine in fuel and I used alcohol and Acetone trying to remove the crud from that valve guide but nothing worked except using the arm of the Q-Tip and steel wool. Removing the valves is a real thrill but getting those little two part keepers back in is no fun at all. Took me an hour to get the second half back in!!
Try to get some good fuel for your engines and I bet you won't be having these kinds of problems.

This time I was careful Gray Beard. I never use castor on my 4C engines. This is a home brew with lab tested methanol and Klotz100 with 20% klotz and 7% nitro. Klotz 100 has 20% castor in the factory mix for a bit more protection for safety, so thats what we use. This engine was a box damaged Tower engine though and was in storage for over a year and half. In that time, I had standard 3-in-1 oil i.e. Singer sewing machine oil i.e. light machine oil in everything including the cam shaft chamber, valve chamber etc. So I doubt that any of that is and issue.

I think I need to move on from the rust issue. My real concern now is the tight compression. Its so tight, the prop is very difficult to turn over compression by hand. It hard enough to physically move the model when trying to turn the engine over. The starter doesnt seem to have problem turning over though. I am concerned that if a valve is binding or something, I may break something in turning it over. Seems to run just fine though

Ameyam

It's simple to check if anything in the valve train is having a problem, just pull your push rods and check to make sure they aren't bent. Those are usually the first thing you will see. As for the compression? We had a freezing cold snap here for a while and I haven't been doing a lot of flying, I don't like the cold. When I pulled out my Extra with a YS 1.20 that engine now has a ton of compression? Runs great and when it has been started and run, there is no problem but my starter with an 18 volt battery doesn't want to roll it over while it is cold? This starter with a full charge will roll over a DLE 30 gas engine. So far I haven't found any reason for all the compression but I really haven't looked into it. I just make sure I charge up my starter battery before I go flying. I plan on flying again tomorrow so when I get home I will check the valve adjustment. It runs so well I just don't want to fool with it. It's not real cold now but it may just be it doesn't like being left out in the van in the cold weather we have at night? I also changed the cone in the starter. The old one is getting hard and not gripping very well. The new one is very soft and should work better?You may just be lucky and have an engine that is holding it's compression after the ring seated?If the push rods are OK I wouldn't worry about it too much as long as it runs well. The steel parts in an engine will rust but as long as they aren't rusted on an operating surface there shouldn't be a problem, just a sign of moisture in the air.

A layer of residual oil will make a ringed engine really hold compression more than they normally would. It's not a problem at all, just a quirk of the engines.

Ok, I will check the push rods as soon as possible. There was no flying over the weekend and coming saturday is our version of Toledo. I burnt the midnight oil servicing the engine on Friday night / saturday morning, so all I could do was test it at idle at home. That was punctuated with the driver being discharged first and the starter battery next. The one time it did run, it purred like a large angry kitten (if you know what I mean). So I can test it at full throttle only after a couple of weeks

Ameyam

Keep in mind we also have the OS support in the glow engine forum and any questions or problems you are having you can ask Bill Baxter directly. When I have an OS problem that is killing off the brain cells I go directly to Bill. Same thing with a YS. there is a lot of expert help over there. Bill gets to see things with OS engines that people like myself will never see and he works on these engines every day. Like getting free advice from a doctor.
Gene

Hi,
I had checked the pushrods for straightness a few days ago but didnt get time upload the video.In any case, it was good so I flew the airplane today. It promptly threw off the 15x6 wooden JXF prop I had gone with. But luckily I had the original 14x8 prop MAS spare and installed that. Since I had just put the cowl in, tuning was off. After a bit of tweaking, it flew like a sports car. The added noseweight of the cowl and incowl exhaust manifold brought the cg more forward and rolling out of KE was reduced. I was happy enough to do figure-8s on the first flight of the day. Tried hovering too, much more stable on the third attempt. But I was out only to enjoy. At high rates it rolls like a drill. Little issue on landing because even at idle it wouldnt sink. Ended up doing several flybys and TOGAs ultimately landed after cutting engine. My mentor was on field after a long time and he just enjoyed the airplane too..He just commented that the 14x8 had too much speed and asked me to goto a 15x6 or so, which I agree

Enjoyed , just two flights though due to a derby and no flying tomorrow. After cribbing initially when cold, once started and warmed up, engine performed like a champ. Hopefully I will enjoy more in the coming weeks. Will load the vdo (only landing though) asap
Ameyam