Originally Posted By: Woody71
I did some more digging on some of the gas/oil treatments. One source indicated that when valves are out of adjustment or stuck, it can cause a rattling noise.
My engine has been doing this for quite some time now, more so when I'm going into longer, wetter grass. It will rattle for about 10 - 15 seconds and then the rattling will stop and the engine goes back to normal operation. I figured it was grass getting deposited on the bottom of the deck. The blade is tight, straight, sharp and the crankshaft is not bent.
That said, I'm going to put some SeaFoam in the oil (it's already in the gas) and see what it does. If it doesn't correct it, chances are I have a problem that's not worth fixing unless it's a simple valve clearance adjustment.
Oil/additive related question: I'm using Peak SAE 30W motor oil that has a detergent/cleaner. Would it be overkill to add SeaFoam? Also, if I were to go with SAE 30 non-detergent, would SeaFoam add the detergent? My mower manual says to use an SAE 30 grade with detergent.
While there is a valve adj spec on these engines it's done when the engine is assembled or if/when a valve is replaced. The adj/lash is measured from the distance between the end of the valve stem and the top of the lifter. When installing a new valve if an adj is needed one just removes a bit of material from the end of the valve stem.
This is not an OHV eng. so there is no "Valve Adj" in the usual sense because there are no rocker arms or push rods..
That being said it is a common problem on these engines for a valve/s to stick. It is "Usually" the Intake and it's generally caused by poor fuel quality or when a unit is allowed to sit for an extended period the fuel gets nasty and covers the valve stem with varnish.
You should be able to clean the valve with a fuel additive but you may want to get some good cleaner right to the valve from the valve cover. This is not a tough job at all and if your a decent DIY'er and handy with hand tools you won't have any trouble.
Remove the muffler, remove the carb & intake (together), and the valve cover is right there.. Remove the valve cover and start hosing down the valve stem with DEEPCREEP, or a good CARB cleaner (or both. Let it sit for a few minutes then with the SPAK Plug "REMOVED" turn the eng over to make sure your getting that cleaner on the entire valve and through the valve guide. Its really a piece of cake so don't let it rattle you..
Originally Posted By: JimPghPA
Re, your post of:
I forgot to run this by the mechanic this afternoon. When I pulled the engine cover and shroud before taking it back up there, I noticed a bit of surface rust on the coil. Would just the rust alone be enough to cause a missfire?
Daaaah, YEA, rust is a very good conductor of High Voltage.
I does not take much to get electric current to flow when it has over 20K Volts to help it along.
Actually there isn't any current/voltage at the flywheel side of the coil. The voltage is made INSIDE the coil as the Magnet on the Flywheel passes the Coil legs.. It's then discharged through the coil wire/spk plug lead. As long as the air gap is correct the magnet doesn't care of there is rust or not.
