Nathan King

For two seasons I have had a two meter with exactly the engine set up refrenced in the O.S. 1.60 Cookbook; however, I am running into reliability issues. The engine runs great on the ground. I can idle it for a minute, give it full throttle, and it's there at about the same time as my finger. I can position the airplane up, down, sideways, or inverted and the engine keeps going without a hitch. When I am flying, it will run beautifully for about one minute and suddenly begins to spool down until it finally stops. I have plumbed the entire fuel system again, complete with silicone sealant and wire tubing clamps. I have also tried a new glow plug and fuel. The engine does not appear to be overheating and it's tuned perfectly. Any ideas on what's going on?

Jetdesign

My Feedback: (8)

Nate, I know with my little experience I'm not going to be much help, BUT:

I had a 1.20 with a pump. Guys were helping me out and could not solve my problem - seemed to idle fine, WOT was fine, transition was beautiful, mid range over 30 seconds loaded up like crazy, to the point where accelerating would make it cut out.

I took the pump out and ran engine at firewall, same exact problems.

Problem seemed to be from some kind of film on the carb. Completely took apart carb and scraped it, cleaned it with acetone and denatured alcohol, reassembled and it's running perfectly. I heard about the film thing being some kind of residue from certain fuels.

Good luck bud.

rcacro

You also should check the main bearing. When they start to fail they can cause running problems.

John W.

jonlowe

My Feedback: (12)

You may have a pipe baffle coming loose and blocking the exhaust as the engine heats it up. Try a different pipe.
When you replumbed, did you use a new fuel filter?
Have you checked the remote needle assembly for leaks? Air in the line will cause that problem. Is the needle o-ring in good shape?
Is there any cooling air directed at the pump? Could be getting too hot and vapor locking.
Is the carb to crankcase o-ring in good shape? As suggested above, have you taken the carb apart and blown out all of the passages?

shepga

I don't use a pump I run the Art Wagner Caveman set up, bladder fuel tank at the firewall. But, I have also run the OS160 with a pump with equally good results. I did run into the same problem you are having when I ran the VP30 Perry. The issue wasn't the pump it was because I mixed 2 gallons coolpower 30% heli with 3 gallons coolpower 15%. Bad idea! 15% coolpower or 15% Ritches Brew is all that is needed. Have you checked the position of your fuel tank? Is the center line of the tank equal to or slightly above the carb? If you have a spare needle valve try swapping it out. The OS 160 carb is practicaly bullet proof. If the engine runs fine on the ground fine and at least a minute in the air, I don't think it's the carb. You have replumbed your fuel lines so I don't think you are getting air in the system. But, the fact that the engine slowly spools down and quits is definitely an indication that the engine is leaning out IMO. My money is on the needle valve.

Glen

burtona

My Feedback: (50)

I vote for a rich high speed needle setting!

RC11

My Feedback: (7)

Mine did the same stuff. I have 3 160s and run Jon's cookbook set up with total success. I was having the same problem as you on a new Black Magic VF3. It would loose power till it quit. I went so far as changing everything out, motor,pump needle valve, fuel tubing.... everything.... and the same thing happened. The VF3 has a ton of inlet and I opened everthing up as much as I could thinking I was doing a good thing. Wrong! Any inlet you have that is not directing air over the head of the motor is hurting the cooling. Block off some inlet and direct as much air as you can over the head with some baffleing. Duct tape over some inlet and give it a fly. Make sure you have at least 2 times the outlet as you do inlet.
This was a solution for me and I hope it fixes your problem.
RC11

br@m

You should check the FRONT bearing, this is a sealed bearing.

When it wears out the seal may leak, causing loss of crankcase pressure, which in turn causes problems with fuel feed into the carb.

Remember the fuel is 'sucked' into the carb because of crankcase pressure/vacuum caused by displacement of the piston.

Run the engine with the cowling removed. If you can see fuel spilling from the front bearing, this may well be the problem.

Nathan King

Some of the ideas posted have been checked but others have not. I recently replaced the bearings; however, swapping them out made no change. I flushed the needle valve, but not the carburetor. That will be next on the to-do list. Thank you all for your ideas.

RC11:

I thought about overheating as a possible cause. While I can't rule it out, it seems an unlikely cause considering the fact that the airplane has run fine for over one year with the same amount of cooling. Would you disagree?

Strat2003

My Feedback: (1)

Rick, why are you up at 4:18 AM?

Nathan King

It was past 11:00am in the Netherlands.

Taurus Flyer

Nathan,
I am a OS Max 61 user and did eliminate the backplate mounted needle valve by using a K & B carb.
Reason was I did discover evaporation in the needle valve assy when the temp of the crankcase became too high for what ever reason, when this happens the engine runs lean with the effect we all know, hot , vapor and more lean.

When this process starts during flight you cannot stop and the engine quit.
I do datalogging on my engine of the temperature!
What I do not know, do you use a backplate mounted needlevalve that can get the temp of the crankcase??
When you use a backplate mounted needle valve I tell you the second part of the story

Cees

Nathan King

Yes, I am using the backplate mounted needle valve. That's an interesting observation. What's the second part of the story? Do I want to know? [:@]

Taurus Flyer

Oké but one question : Do not shoot the messenger! (LOL)

First I did make one fault I use a Moki Carb but the story is the same.

When the engine runs lean the temp of the engine rizes and I did measure temps of more than 200 degrees C, 392 F of the engine head.
During flight the front end of the engine is cooled down by evaporation of the fuel in the carb and propwash.
When the engine quits after running lean by evaporation in the needle valve assey, the total energy in the head and cilinder of the engine will be divided over the whole crankcase,
The temp of the crankcase can rize to a Temp the main ball bearing will not keep his position and can slip backwards in the case.
After the engine is cooled down the main ball bearing CAN BE in a wrong position, you can feel that on the crankshaft, you can feel the resistance to rotate the prop,

When you try to start the engine in this situation you destroy the (main) ball bearing.
I did not discover the front bearing problems but main ballbearing problems, I think by the much greater radial forces of the piston on the crankshaft!
The difference can be, I never use a electric starter motor and with a wrong main ballbearing position all the axial forces of the starter motor are for the front bearing!!!!!
Sometimes people do use a starter motor like a hammar, then it can go wrong!


Reason of a too high temperature of the crankcase I also think is bad ventilation of the crankcase of the engine so extra risk!!
Let it be clear, the ventilation of the crankcase outside is not the main reason of the problem, bad ventilation can give extra risk of bearing failure ater running lean!

End of part two, but again, "Don't shoot the messenger!"

Cees

RC11

My Feedback: (7)

Nathan,
Problem just started after a year? I would agree then that you should keep looking elsewhere. Jon recomends to mount the needle
to the airframe. Strat 2003.... Untill I am able to retire' God and OBama willing, I'll have to be at work at 4:18am watching my system and attempting to stay awake with RCU. Hope to see you this week. Wings level? What a concept!!!
RC11

Taurus Flyer

And then part three of the story,

Mount the needle valve on another cool place near the engine, and that's why I use the Moki carb with enlarged bore.
To keep the ratio constant I use a fuel pressure regulator (like Cline).

Cooling wil always be important of course and running lean also with the better cooling will never be good for the engine.
Constant fule/air ratio I find most important especially with fuels without castor oil in en engine without ring.

Story complete. Maybe you can use it.

One extra note, sometimes there is a spring washer in front of the front ball bearing that keeps the bearingset and crankshaft in most forward position. (red colored)
When you hammer this spring washer flat with a electrical starter motor, the crankshaft has axial play and can position in the most backwards position after stop.
When the engine was overheaten, the main ballbearing ALSO can go backwards. After cooing down the crankcase will be shorter than the shaft and bearings faults can be the result.

Cees

Nathan King

Cool. I do not use an electric starter but will look closely at the bearings.

Taurus Flyer

Nathan

Most important, keep your needle valve cool, especially when leaning the engine, to prevent vapor lock!

Succes Cees

Nathan King

Gentlemen, the mystery is solved. After a closer peek at the internals, I found that the rear bearings were a bit tight and shaving. Apparently, the replacements I bought weren't very robust. That would explain the overheating symptoms. Where would you guys recommend I order a new set from?

Nathan King

These any good?

http://www.bocabearings.com/main1.as...&n=SMR6004-2RS

http://www.bocabearings.com/main1.as...2&n=SMR6001-ZZ

Taurus Flyer

Not solved, do not forget part 3 of the story, because when you forget this part you better order a few sets!
Look also to cooling, needle adjustment, plug, fuel etc, to prevent the engine will run lean again.
Bolt part of your post is nonsense, is the result of the basic problem!!!!!

That was why I did start with: Don't shoot the messenger!

Succes Cees

CW

Nathan,
I have been having similar problems with my OS 160. After 450 flights it was down on power a bit so I put in a new ring and liner. After run in I started having problems with it stopping. My set up is OS140 RX pump in backplate with Mintor 170 aluminium pipe. Tried tuning top and bottom to no avail. Went back to Perry VP 30 pump- still no improvement. Checked the pipe- it unscrews -so easy to confirm no problems in there. Cleaned out the carby and needle, replumbed the tank etc etc. Cleaned out the RX pump- it had some sticky gunk on the crankcase pressure side- fuel side very clean. The symptom was the engine would start and run fine at idle and at full throttle but would stop at midthrottle particularly when the glow driver was removed. Changed plugs and after 1 or 2 run ups the same thing happened again.Changed fuel- no change. Looked like it was stopping lean in the midrange. Because the symtoms were similar with both the Perry pump and the OS 140 RX pump I concluded that the pump wasn't the cause. Decided to replace the O rings in the carby but before I did that remembered I had a Mintor 170 in the drawer so decided to check the carby and sure enough the spigot diameter for both carbies was virtually identical. All I had to do was drill and tap two holes in the Mintor carby and bolt it on. Put the OS 140 RX pump back in and screwed the pressure in 1 1/4 turns back to the original OS setting. Once retuned the motor ran fine after that. About 20 flights so far with no problems. My situation is similar to yours in that the motor had run fine for a long period. On the face of that and given you have done bearings, plumbing and flush out I would suggest the problem may be the carby- a good clean out, new O rings etc would be where I would be looking.
Good luck with it.
Cheers,
CW

Taurus Flyer

CW,

When the the engine runs lean in the midrange he temp will rize stc etc.
That was I did write in my first post:

Reason was I did discover evaporation in the needle valve assy when the temp of the crankcase became too high for what ever reason, when this happens the engine runs lean with the effect we all know, hot , vapor and more lean.


That csarb that you mounted did gve a richer midrange than the old carb, so you did not have troubles anymore.

I still have some picture of my OS Max, for I long time I do use a MVVS on that plane

The red led is a three color LED. blue below 14 C (engine too cold to start!) green (duty cycle) info temp 150 - 185, red overtemp 200 degrees C.
With an overtemp the red light is still "on" also after the temp is lower then 200 degrees back on the ground.
After a dead stick you cannot always detect it was "overtemp"!
With this "set-up" I didn't have any deadsticks anymore!
Datalogger , engine with Moki carb

Cheers,
CW


oh sorry (my initials?)

Cees

CW

Taurus Flyer,
I'm sure your hypothesis is correct. I believe the engine was going lean in the mid range. It happened very quickly while testing on the ground- in the time it takes to go to full throttle- hold for a couple of seconds and then would cut immediately when the throttle was moved to mid range.The engine was not lean at the top end and the idle was good- 1600-1700 revs. Not sure how quickly the engine would overheat but the cut was as soon a mid throttle was reached. My key point is that this engine had run well for 450 flights on the same pump pressure and needle settings then something changed. It looks like the "something" was the carby. Interestingly a previous OS 160 had similar problems around 500 flights. I didn't get to the bottom of that problem then- had a new OS 160 for the next plane so just put that in my model. When I tried the Mintor carby and OS 140 RX pump on that engine it too ran well- at least in the test stand- haven't tried it in the air. A good test will be to try the OS carby with the new o rings and see if that solves the problem.
Cheers,
CW

Taurus Flyer

CW,

Thanks for response, I will not forget your message.
As soon as I know more you will hear that from me.
I do not have more input as this on this moment.

Succes

Cees