***"BLACK would indicate oil fouling"*** Not necessarily the exclusive deciding factor. The black color only indicates carbon. The source of the carbon will be revealed by other facets of the carbon deposits. Carbon deposits due to lube oil will have a glossy look and will be quite gummy/sticky when scratched. Also the built up deposits can be quite thick and uniformly cover everything about the spark plug completely. Carbon deposits due to a very rich fuel mixture are sooty and powdery looking, and when scratched, will readily shed dryish flakes or specks. Often, where a rich mix is causing carbon, you might see places on the spark plug where the carbon has already flaked off or areas where the carbon seems not to be as thick. A poor boy's method for testing/guessing at compression issues can be done using compressed air. If using this technique, you will need both valve covers removed. You will need an adapter fitting that threads into the spark plug hole and accepts to being fitted to a shop air hose. The engine must be rolled to the correct position (piston 1/4" down and beyond TDC point of the COMPRESSION stroke) for the cylinder being checked. The engine absolutely MUST BE HELD FROM TURNING by some means to prevent the piston from reacting to the compressed air. You would have to figure out how to hold it with what you have on hand. An alternative method that does not require engine to be "locked" is described at the end of this description, so read carefully not to get the 2 confused. Air pressure needs to be 90 PSI to 120 PSI for best results. The air hose and all fittings need to be free of leaks as you will be "listening for leakage" in the test (and any air leaks in the plumbing can dull your testing accuracy). Each cylinder must be tested individually and the piston for each cylinder must be in the correct point, which means you will have to go through the locking and unlocking of the holding device for each cylinder. Once the engine is rigged against turning, apply compressed air to the cylinder you are testing. Now, you must listen carefully for air leakage. I use a 3 foot length of 3/8" plastic tubing to pin point the leaking spot/area by using it like an impromptu stethoscope. Hold one end of the tubing near to one of your ears (but don't stick it in your ear) and probe the following places on the engine with the other end of the tube: Get inside the valve push rod area of the cylinder head where the head meets the block. If the head gasket is leaking, that is where the leak will be. If you hear air leaking, and it gets louder as you probe nearer to the head/block juncture, and begins to become quieter when the probe goes deeper into the gallery (has moved past the head/block juncture), you have located the leak. But.....if the noise level continues to increase the deeper into the gallery the probe goes.............the leak may be coming from the opposite cylinder head or rings. So you have to test BOTH cylinders the same way, but one at a time. If you find that escaping air noise heard through the plastic tube increases on BOTH cylinders the deeper into the galleries the probe is inserted, and you do not hear an obviously louder sound when the probe tube end is positioned right next to either head/block juncture seam.......... the air is escaping past piston rings. This test method will also identify valve leakage by placing the probe tube into the exhaust/muffler or the intake/carb locations. There is also an alternative to rigging a holding fixture to keep the engine from moving under the influence of the compressed air. The alternative way is to REMOVE the push rods from the rocker arms of the cylinder you are testing and simply place the piston at BOTTOM DEAD CENTER (BDC). With the push rods removed, the terms compression, power, exhaust, and intake stroke become meaningless, as both valves are closed. The push rods must be marked so as to get them back exactly where they came from. It only requires finger tip pressure to push the valve spring down to remove the push rods. My thoughts on the Vanguards having "head gasket issues" are that the "true Vanguards" (and the 303700 is a true Vanguard) do not have any ill repute for head gasket failure. On the other hand, the Briggs single cylinder OHV 280000 and 310000 engines DO HAVE somewhat a reputation for head gasket blow out. Same goes for the Briggs V twin OHV engines that are just based on having one more cylinder of the same design as the 28 and 31 OHV Intek family (405700 and 445700). This post was edited by mownie on Tue, Feb 4, 14 at 12:02

Been a bit busy with the yard to respond before now. It's now due for another trimming with the Toro self-propelled I ended up with (a 2hr plus task last time that is bound to take a bit longer this time since I skipped one side yard and the front yard the first time round). As for the Craftsman...I've drained the fuel on it (the fuel had stabilizer in it but better safe than sorry) and will be taking the battery out to place it on a trickle charger until I can get it over to the one place that will service it since it doesn't look like they will be picking it up for me after all. Perhaps I was just plain unlucky but the problem I've been having was NOT due to lack of maintenance on my part. I've been very careful to do the recommended maintenance and have had no problems with the engine, etc. A defective safety switch is not a maintenance issue. I just wish the problem hadn't been intermittent for so long or I would have considered coughing up the $50 service charge when it was still under warranty. I was concerned that the problem wouldn't show up and I'd be out the $50 with nothing to show for it (okay and I -was- irked it cost that much when the lawnmower was still under warranty). With just one mower to base this problem on I can't say whether it's a common one or not...just that other people I've talked to seem to have had similar headaches with service and it's something well worth considering when purchasing a new lawnmower. I've also found standard air filters, etc. to be far more expensive than other brands so that's another thing to consider as well. Fortunately the most expensive part, the air filter which runs $25 at Sears, appears to be a standard Briggs and Stratton part that can be obtained elsewhere for less than half that (quite the discount, eh?). Now...to get back to that lawn. I don't suppose anyone has some sheep I can borrow for a bit...say the rest of the summer? Actually now that I think about it...anyone know if replacing a safety switch on one of these things is a DIY project? So far I've heard...it depends... From the way it's acting I've been told it may be the clutch safety. Perhaps I can work on it after fixing the trailer lights...or before since I then wouldn't need it so desperately... Just as an additional point...sometimes the inconvenience of having something like this out of service for so long can more than make up for a couple hundred dollar price difference. Now if one's talking about several hundred dollars...I'd go for the sheep myself...;-)

Seat switch connector has a built in "shorting bar" which will close the kill circuit when the connector is unplugged from the switch. Unplugging the connector from the switch gives the same results as if the seat is not occupied. Seat switch is just one switch in the safety interlock circuitry that can cause the engine to have no spark. The brake pedal interlock switch is actually 2 switches in one assembly. One of the brake switches is dedicated to starter inhibition, and the other switch is to kill spark and stop the engine. The PTO switch also has a circuit dedicated to the kill wire. You can disconnect the kill wire from the magneto to see if that restores spark. If doing that restores spark, something is grounding the kill wire somewhere. Could be a chafed wire.

Yeah, it's an old thread but I still see more posts coming in on a subject that struck me as both very serious as to personal safety and property loss - but also one post, or poster's reaction was interesting if not humorous which I felt deserved a response... Contributor kompressor made an impressively verbose series of posts on this topic. Quite clearly this is a topic that was once very near and dear to kompressor and kompressor is projecting as an authority on US libel laws. Here's my tongue in cheek $0.02 on kompressor's extensive commentary... First kompressor states: "The OP should have read the terms of the warranty prior to paying his $1700.00" Then kompressor states: "You cannot run around the internet making wild accusations that you cannot PROVE happened in a court of law" Now wait a minute? Did I here correctly? kompressor just stated he paid $1,700.00 How does kompressor KNOW the OP really paid $1,700.00? kompressor made a 'wild accusation' about $1,700.00 but I fail to see where kompressor has proven in a court of law that he really did pay $1,700.00 kompressor claimed. Finally kompressor states: "The next day, the thread was GONE. WHY? Because of potential libel issues." Oh? kompressor just claimed some thread was removed because it was potential "libel". Did kompressor prove in a court of law that the thread was removed "Because of potential libel issues". Or is kompressor just going around the internet sayin' stuff? :o) Actually the OP can go around the internet saying stuff, much like, well, ... kompressor just did. The above was meant to be illustrative and tongue in cheek. On a more serious note kompressor states: "Yes, there is a warranty and the warranty states that if the tractor burns, the warranty won't cover the damage...end of story." All consumer warranties are subject to FTC regulations. I do not agree that it is the 'end of story' and do not believe it is true if the fire results from defective materials or design. Nor do I believe kompressor's statement to be true if it is a larger safety issue. Establishing this is of course a different matter. There is a very good up side to the OP (and others) sharing of his experience (or "wild accusation" as you will). Others may come forth with their own, uh, "wild accusations". Enough "wild accusations" and a statistically viable pattern might emerge that could be directed to the CPSC to take notice and open a case, maybe even induce a recall for a modification or something. A group may have greater influence. Maybe word gets out and people start taking extra precautions and that averts a potential injury, house fire etc. Maybe the manufacturer takes notice and identifies a potential problem and takes voluntary steps to address it. kompressor is correct in one regard - we just don't now the specifics of any one instance. Yet. But if we suppress the sharing of information because someone goes around on the internet saying stuff like "libel" we likely never will either. Safe mowing everyone!