Cox Motor Issues

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This is the venturi.

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I actually managed to get the motor to run. I don't know what i did. I took it apart to check venturi gasket which wasnt there then i flicked it over a couple of times and it started and ran at 2 1/2 turns. I killed it with needle valve and tank was empty so i am losing fuel from somewhere. I didnt run it long enough to drain rank. I will get new gaskets for it. I will also get reed valve because it does pop alot when trying to start it.



P.S. Sorry Admin if i made the topic twice.
P.P.S Can anyone identify this motor? The cylinder and piston are of a newer style with small slits. It also says made in the USA.

I believe fuel starvation to be the issue here. A venturi gasket, if not to be found, is certainly a suspect as could be the fuel pickup line in the tank which could be plugged with "goo". Also consider a blocked needle valve seat.

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I have checked the needle valve seat and the pick up line and both are clear. The previous owner stored it in wd 40 so that is probably a factir. The first time i took it apart there was goo in it but air still went through it. Now it is clear.

Disassemble and soak your engine in some new fuel or 91% isopropyl alcohol overnight. Yeah, either out of a EZ Bee, or a Babe Bee that someone tossed a muffler on. Probably not a QZ, since the QZ was discontinued around '77 and the hex snap starter came later.

Admin wrote:Disassemble and soak your engine in some new fuel or 91% isopropyl alcohol overnight. Yeah, either out of a EZ Bee, or a Babe Bee that someone tossed a muffler on. Probably not a QZ, since the QZ was discontinued around '77 and the hex snap starter came later.

I would say it is an engine made of spares not a production model it is prpbably the venture gasket.

Original problem sounds like venturi gasket to me. You dont need to buy them, you can make them yourself from large dia. fuel tube or you can buy them. Might be best to buy them in your case.

Another thing you should check is where the fuel pickup tube is situated. The tube will be placed to one side for control line use or to the bottom for free flight or radio control use. If it is placed to the side then it will not use the whole tank on the test stand.

Regards
Warren

Godsey3.0 wrote: ......I took it apart to check venturi gasket which wasnt there then i flicked it over a couple of times and it started and ran at 2 1/2 turns.

If the venturi gasket is missing, it will have to be replaced. With the gasket gone, the engine will run very rich (if at all) at the beginning of the run until the fuel level drops below the venturi tube, then it will go lean as air is sucked in.

Secondly, if your engine has some age on it, the fuel pickup tube has likely hardened -- this should also be replaced. When it hardens, it won't seal on the fuel nipple on the backplate and the engine can suck air, causing either a lean run or difficult needling. This can be replaced with a piece of small ID silicon fuel tubing. Just make sure it reaches to the bottom of the tank (for R/C) or to the lower right hand side (for C/L). I tend to cut the end at an angle just to ensure that it doesn't sit flat against the backplate or tank side.

A new set of gaskets, fuel tube and reed, if yours is dimpled or bent, would likely be your best bet rather than chasing problem after problem. Gasket kits are available from COX International and will cover the bases for you.

I could only add to Andrew's suggestion to be sure the sping within the pick up line is free of obstruction. It also serves as a rudimentary filter to catch "stuff" before it is sucked into the venturi.

Godsey --

I looked at your original eBay listing and attached images. That engine was showing a lot of external corrosion on the backplate and may well have internal corrosion. If any of that has broken loose and gotten into or blocked the NV orifice, it may explain some fuel starvation issues. Even though you may have soaked the backplate, the corrosion is not soluable and could remain. A thorough soaking (I prefer denatured alcohol or acetone) followed up with blowing out all passages usually clears the problem. DO NOT poke around with wire or other metal tool --- you can gently clean seats and passages with a sharpened toothpick. Just be sure not to break a piece off.

I had also wondered if your engine had a plastic backplate, but it doesn't. There have been some issues associated with the plastic backplates distorting if they have been overtightened and left to sit for a long time. That's not going to be your problem.

Realistically, take Mudhen's offer of repair --- send it to him and let him get it back on its feet. Older engines can be cantankerous at times and letting someone with experience get it running can save a lot of frustration.

Edit: WD40 is not a good long term storage solution. Over time, the volatiles will evaporate and leave a hard, dark deposit that must either be chipped off or dissolved with a strong solvent. I use Marvel Mystery Oil. Some folks will use a 50/50 mix of Marvel Mystery Oil and ATF, some use Marvel Air Tool oil and some use ATF alone. I've read comments that Marvel also will dry out over time, but I've never had that problem. I think that it may be due to the fact that I hit my engines quite heavily (pickle them, if you will), then store in heavy duty ziplocs. Before sealing, I squeeze as much air out of the bag as possible, then seal. I think that removing as much air as I can, then having an airtight seal keeps it from drying out over long storage periods.

andrew

I got the motor running. It was the venturi gasket. I don't know why I didn't go ahead and put one on in the first place. Would have saved a lot of headache. Thanks everyone for helping. Now to get this motor in a plane. I am thinking my first control line.

yeah, when i read this, the first thing that comes to mind is the venturi gasket; dirty reed or a dirty needle valve. Great you got it running! for my long term storage oil, i use air tool lubrication oil. It has never dried out on me before. I did find a babe bee submerged in a jar of oil at a garage sale. it was literally on the bottom of a 1/2 pint jar of clean motor oil. I bought that engine for only $8 about 2 years ago.

Carl wrote:yeah, when i read this, the first thing that comes to mind is the venturi gasket; dirty reed or a dirty needle valve. Great you got it running! for my long term storage oil, i use air tool lubrication oil. It has never dried out on me before. I did find a babe bee submerged in a jar of oil at a garage sale. it was literally on the bottom of a 1/2 pint jar of clean motor oil. I bought that engine for only $8 about 2 years ago.

did it run well Carl?

The Sig Dewey Bird is a nice little flyer

http://www.ebay.com/itm/Sig-Dewey-Bird-Control-Line-Kit-Norvel-Cox-049-/300597487376#ht_500wt_950

Cheers

Godsey3.0 wrote:I got the motor running. It was the venturi gasket. I don't know why I didn't go ahead and put one on in the first place. Would have saved a lot of headache. Thanks everyone for helping. Now to get this motor in a plane. I am thinking my first control line.

Have a look at the SIG Skyray. It is simple to build, easy to fix, and has external controls that can be adjusted from minimum control (beginner) to maximum (to do stunts).

There are many choices, depending on your skill.

Good luck

George

I now have more issues with the integral tank. I put the tank on my diesel bomber to run with nitro fuel and it hydro locked. I took the cylinder off and fuel leaks right into the crank case. Do I just need to get a rebuild kit for this tank?

probably or a new tank.
Try the rebuild kit maybe you have a fouled reed.

Thats what I thought it was at first but I tested the reed and it seems to be fine. It doesnt have any holes. There are no holed in the venturi tube that goes through the tank. I was hoping it was the venturi gasket.

Will this stop fuel leaking into the crankcase? I was using two DC gaskets.