18.5 ohv starting problem

hello i have a cub cadet lt 1018 with a 18.5 ohv single cyl 31q777 won't start turns over back fires threw carb. so far changed head gasket, fuel drained and fresh put in, flywheel key. before i did all that it oly turned over half turn and stop, is there anyway to adjust timing acts like it wants to start but won't. any thoughts anyone please. thanks

 

Do both valves close fully? Are the valves properly adjusted? Tried a new spark plug?

 

Yes sir i have put a new spark plug in, i think but not positive i adjusted the valves correctly on a 18.5 ohv i set the top valve to .004 and the bottem to .006 is this correct, that is with the tdc minus a 1/4" is when i set it ( turned clockwise facing the enginge to lower the piston).

 

Sounds like you did the valves right. Any chance you put grease/oil on the crankshaft or flywheel before putting the flywheel back on, or maybe the flywheel nut isn't tight enough?

 

I had this happen to me once also and the problem was that the valve cover was on the front of the engine and was just dented enough to prevent the intake valve from operating properly.

 

"31q777"

"i adjusted the valves correctly on a 18.5 ohv i set the top valve to .004 and the bottem to .006 is this correct, that is with the tdc minus a 1/4" is when i set it ( turned clockwise facing the enginge to lower the piston)

I do not agree that this is proper procedure. For one thing the top valve is the Exhaust - .006" and the bottom one is the Intake - .004" and it is 1/4" down PAST TDC turning in normal rotation.

Detailed instructions at address below, put in proper format and remind me.

Walt Conner

 

Turning the engine clockwise would put it PAST TDC on normal rotation, and .004" and .006" are fine for either valve, it should run this way. Something else is wrong.

 

"Last edited by cheese; Yesterday at 10:40 PM. Reason: Email addresses, whether in proper format or not, are not allowed per the site rules. If you want to help, why not post your information here for others to benefit from.

Read more: http://www.doityourself.com/forum/outdoor-gasoline-power-equipment-small-engines/468143-18-5-ohv-starting-problem.html#ixzz1qyfhQkRL"

My Instructions are much too long to take up space in the forum and include how to test the compression release PLUS a tip which may result in saving money in the long run and head bolt torque instructins. His valve adjusting procedure was not correct and makes a good starting point and most likely now the flywheel was not properly torqued resulting in sheared key. It also includes what may well be the "something else" causing the problem.

Sorry OP, you can find me via Google.

Walt Conner

 

Walt, let me start by saying I remember you being here some time ago, and I recall you have more than just shadetree knowledge of these engines, so I don't mean this with dis-respect... but...
I don't know what your intent is here, and why you can't copy and paste right here instead of in an email. This is a simple briggs and stratton single cylinder engine here. No majic tricks, no special instructions, and no engineering degree required. Some of us here know this engine better than the back of our hands and have as much or more knowledge about this engine as you or most anyone else.

You know the engine will crank and run with the valves at .006 and .004, no matter which valve is set at which. Now if we commence to the next step and discover there are signs of a failed compression release or a worn cam lobe, then we will address that, but at this point, I don't see the need to go there. I definitely don't see the need to post head bolt torque instructions yet. We just need to find out why it isn't starting up. The engine being 1/4" past TDC eliminates the compression release from interfering with the valve clearance. Your post is conflicting information, saying the valve adjustment is incorrect, making an issue of it, then saying it's a good starting point and that the flywheel key is probably sheared, which I already mentioned earlier on in the thread.

If you want to help people on this site, feel free, but requests to email you for special information that you cannot share here is fishy.

 

"that is with the tdc minus a 1/4" is when i set it ( turned clockwise facing the enginge to lower the piston

Well Cheese, If I understand English, setting the valves at TDC minus 1/4" would put it 1/4" down BEFORE TDC. Perhaps you don't think that matters either. My instructions are written very detailed so a novice can feel confident in what he is doing and as I said included compression release instructions plus a way to save problems and money in the long run. My instructions are filed to save time and there is a good reason for including head bolt torque instructions.

I expect it would be better if you just removed my registration as I am not interested in continuing on this forum.

Thanks,

Walt Conner

 

If you read the post, he said he rotated the engine clockwise to lower the piston, as viewed from the top. That means it is past TDC. Are you suggesting this engine runs backwards? Of course it matters whether it is before or after TDC. I am now suspecting your secret instructions are "for sale".

If you can't understand my skepticism, then you haven't spent much time on internet forums. Always a scam, always someone looking to sneak a buck, and you violating forum policy is your fault, not mine. You clicked the "I have read and agree to these terms" box when you joined.

 

FlashJr,

Sorry this thread took a tangent. We keep close watch on these forums to try to maintain the high level of professional information and lack of spam. While the offer may have been genuine, it was fishy, there is no way for us to know and it was in violation of policy. If you want to know his "money saving tip" involving head bolt torque, he likely wants to tell you to re-torque the head bolts while the valve cover is off, since these engines have a tendency to blow the head gasket between the cylinder and the opening for the push rods to go through. Not a bad idea to do if you have a torque wrench handy and are so inclined, but not necessary at all.

Have you had a chance to check the flywheel key yet? If so, please post back with the results. I'm pretty sure you will find your problem there.

 

Thanks for the help sir, yes the flywheel key is broke in half, i will replacing it on Friday. also i did retorque the head and i will adjust the valves .006 on top and .004 on the bottem. 1/4" past tdc. what should the flywheel be torqued at?

 

Hello FLASHJR,

The torque your looking for is 100 ft.lbs.....

Also just to add, Here's a quick run-down on the secrete of checking the automatic compression release mechanism;


Good Luck

 

31YTech, now you've done it, that's too much info to post on this site.


Flashjr, just make sure there is nor grease or oil on the mating surfaces of the flywheel and crankshaft before assembling it together or it will shear again.

 

I did everything as directed. now it still won't run turns over no spark at he plug now, i will be tracing all the wires to see if something broke. what a pain this engine is.

 

There is a small black wire plugged on to the bottom of the coil. If this is pinched and shorted, it won't spark.