OS 46 Prop nut problem!
 

Hello,

I tried starting my new os 46 with an electric starter and the engine wouldnt turn over on the first 2 second run. When I tried it again the whole spinner came off. I thought the problem was the spinner and maybe not having the nut on tight so i bought a different spinner and really cranked hard on the nut to make sure it was on super tight. I tried starting it again today with the same results the electric starter just spun off my spinner and prop. I have never used a quick fueler before and i don't know if this is the problem. Any suggestions on how to get this engine running would be great! Im really frustrated at this point.

Thank you,
Brad

RE: OS 46 Prop nut problem!
 

Hey Bruce does it sound like it might be flooded and not letting the piston go to the top. Might try taking the glow plug out and putting the starter on the spinner and see what happens.

RE: OS 46 Prop nut problem!
 

Most likely you are flooded or over-primed. Dry the engine out well. Then with the glow battery removed and the carb open cover the carb intake with your thumb and (by hand) turn the engine over until fuel in the line just reaches the carb inlet. Then give the engine 2 more complete turns. Set carb/throttle to just above min idle setting (stick down but trim high usually). Attach glow battery and apply starter for a few seconds. Should now be running. If not, try starter again.

RE: OS 46 Prop nut problem!
 

Need to be careful doing that. Can get a face full of fuel. Put a cloth over the plug hole to catch the spray and then motor the engine to dry it out (carb closed). This way you will have a known starting point.

RE: OS 46 Prop nut problem!
 

#1 never prime an engine that you are going to use a starter on #2 if using an electric fuel pump always disconnect the muffler pressure line to avoid filling the muffler and engine with fuel, if you are worried about spilling fuel get a small fuel tank that you can connect to the muffler pressure line as an overflow tank. If this is a brand new engine that you are breaking in on the bench i would get rid of the spinner and just use the nut, also heating the engine a bit with a heat gun can aid in starting a new engine.

RE: OS 46 Prop nut problem!
 

Also, make sure you've got the prop tight. The nut holding the propeller tight on the engine also holds the spinner tight. The front of the spinner just holds onto the backplate. When everything comes off, it's because the prop nut isn't tightened enough to hold everything on. If just the front of the spinner was loose only that would come off.

Sometimes the spinner backplates don't give the engine's thrust washer (the part with the gripping teeth) something to grab hold of. Sometimes just a little extra tightening of the prop nut can do the job, sometimes not. But for sure, it everything is coming off, it's because the prop nut wasn't tight enough.

RE: OS 46 Prop nut problem!
 

Hi cheese_puddin
One problem I see is that the nut being tight is a relative term. What is very tight? For years I used the small cross wrench that is used to tighten the glow plug and the prop nut. I would tighten the prop nut "very tight". Occasionally the starter would turn the nut off. Now I use an adjustable 8" wrench. To get a feel for what to do I first used the old cross wrench and tightened the nut "very tight". I then used the longer wrench and tightened the nut "more". I have never loosend the nut again with the electric starter.

RE: OS 46 Prop nut problem!
 

Yea, you really need to tighten that nut with everything you got. You won't strip it.

Austin

RE: OS 46 Prop nut problem!
 

Just to get a bit techo...sorry :) ...with a 1/4" nut the proper torque is around 8 or so foot pounds. Like Villa, I've used the small cross wrench with no problem either hand or electric starting. Ideally you should use a spanner made for the size nut on the engine because the length is designed so that the average person will get it close to the right torque with a little effort.

The trouble with starting an engine is that (apart from the back flip) you use a torque in the direction that's trying to loosen the nut. Any lack of friction somewhere (usually a plastic spinner backplate) will let things slip and then you have a loose nut. Hard plastic props like an APC can give trouble too because some engines don't have a prop driver that can dig into the prop to get enough grip. Probably the wort thing is spinning up the electric starter then slamming it onto the spinner/prop because it's acting like an impact wrench. When an engine is running the firing impulses are trying to tighten the nut.

RE: OS 46 Prop nut problem!
 

I'm guessing there's a hydraulic lock.

Try flipping the prop by hand backward a few times (With no glow driver)

RE: OS 46 Prop nut problem!
 

You flooded the engine. Take out the glow plug, put a rag over the hole, and the turn over the motor with your starter until there is no fuel coming out. Then put the glow plug back in and start it, no need to prime with an electric starter.

RE: OS 46 Prop nut problem!
 

I have sripped and even sheared grade 5 and grade 8 capscrews, size 1/4-28NF which I believe is the thread size used on my OS 46 engines. It must be understood that not all prop threads are that size. It amazes me how easily that size capscrew can be stripped or sheared, though I have never damaged an engine thread. The prop nut and shaft thread are probably equal to a grade 8 bolt which has a recommended torque of about 13 foot pounds. A grade 5 is about 10 foot pounds. Let's assume grade 5. That is a 10 pound pull with a 12 inch long wrench. I just measured my cross wrench that I use on my glow plug and IN THE PAST USED TO TIGHTEN MY PROP NUT. The torque arm on that wrench, when it is in your hand is about one inch. To produce 10 foot pounds of torque with a 1 inch long wrench you need to push on the wrencj with 120 pounds. (10 foot pounds equals 120 inch pounds). This is why I use an 8" or 10" adjustable wrench. Here is a test I recommend: Put a grade 5 capscrew (3 bars on head) or grade 8 (6 bars on head) in a vice and put two nuts on it, preferably of a grade equal to the bolt. Use a 10 inch wrench and pull on it (NOT PUSH) till the bolt failes. You will have a better idea of what you are doing to your engine.

RE: OS 46 Prop nut problem!
 

Yep but put a paper towel or something over the plug hole ...fuel showers aren't all that much fun[X(]