[SOLVED] Lawnmower gets hot and quits

Forget the damn valves, that's not the problem. You've been given sound advice by several people: check to see if you have spark when it's hot and not working. I'm betting you don't, because the magneto has failed.

Reply to
Doug Miller
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This is an outside possibility, but I had a lawnmower with a leaking head gasket. Problem was it would leak only when the engine was hot. The problem was getting worse and worse and I could not figure out what was wrong. The gasket finall degraded to the point that that when I happened to brush my hand ove the head, I could feel the hot gases leaking from the head gasket. Gary Dyrkacz snipped-for-privacy@comcast.net Radio Control Aircraft/Paintball Physics/Paintball for 40+

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Reply to
Gary Dyrkacz

Many, many air-cooled engines develop this problem. The odds are overwhelming it's your ignition module, and they're a bastard to troubleshoot [except, of course, by replacing the module].

As soon as the engine starts to cool -- long enough to check for spark

-- the module cools down enough to check as OK. It's very possible you'll check the spark and it'll be OK.

They're easy to change, but shop carefully. The price for replacement can vary radically.

Reply to
Robert Barr

I may well be misaken. But I've seen valve clearance problems several times before. Though, coil problem is a bit easier to fix. How about find another coil to try for awhile?

Reply to
Stormin Mormon

How about checking for spark when hot first, as has already been suggested (several times)????

Reply to
Duane Bozarth

....

It's a four-year old mower and a non-vented gas tank is the problem? Don't think so... :)

Mayhaps the vent is plugged, but I'm still not convinced...there's got to be an existing vent if that is the problem or it wouldn't ever have run reliably...

Reply to
Duane Bozarth

The cap is hard rubber with a rubber washer that has 2 small holes in it. Behind the 2 holes is another flat thin rubber washer that has deterioated and the deteriorated rubber is actually protruding partially thru the tiny holes. I suspect it completely stopped up the vent holes.

I tried removing the deteriorated rubber, but can't really get to it. If she comes in bitching about the mower dying again, I'll add a new vent hole thru the cap.

Reply to
JimL

Rick says "Check the vent on the gas cap, too".

Well, Bingo! Rick wins.

After checking for spark after it died, and getting a positive response from my wife on spark, I replaced the spark plug cap and reached up untwisted the gas cap off a 1/4 turn and it started on the first pull.

Now, I looked and I don't see any hole in the gas cap for it to vent. I hate that she has to mow with the gas cap not tight. She might catch the mower on fire. I'd hate to lose that old mower.

Do I just drill a small hole in the cap?

Sherman.

Reply to
Sherman

Seems like a lot of work for one guy. She's cutting the grass so it is her responsibility to take care of the dammed thing. Tell her to drill the hole.

Be sure to report back with the results when you do!

Reply to
Edwin Pawlowski

Ed, he won't be able to sit down to type with that drill up there...

Reply to
Doug Miller

You are right. The vent is plugged.

The cap is hard rubber with a rubber washer that has 2 small holes in it. Behind the 2 holes is another flat thin rubber washer that has deterioated and the deteriorated rubber is actually protruding partially thru the tiny holes. I suspect it completely stopped up the vent holes.

I tried removing the deteriorated rubber, but can't really get to it. If she comes in bitching about the mower dying again, I'll add a new vent hole thru the cap.

Reply to
Sherman

Until the electrical issue is addressed, you're simply fiddling with parts that are more than likely functional; change out that ignition coil.

Reply to
D Mecate

replying to Sherman, Marc Belanger wrote: The lawn mower is probably losing spark. It will get good spark if it is cold, but once hot, one of 3 things could be happening. First, the spark plug could be filled with crud, and when it is cold, the crud has a lot of non conductive grease in there. This will turn to a liquid when hot and become conductive enough to short out the coil pack and kill the spark. I would replace it if it looks like there is crud between the edge of the steel and the porcelain on the inside of the spark plug. Look between the metal electrode and follow the porcelain where you can't see it anymore.. Yeah, thats the place, either clean it out and get the bl;ack stuff out, eliminating the short and it will probably work again. if not, the spark plug wire may be cracked and work while cold, but once it warms up, the break is separated enough not to work. Same thing with the coil. Or, the coil could be hust loose. It needs a ground to work and if the coil is loose, when cold it may be connected electrically then when it warms up it may disconnect. The coil and spark plug wire are one piece on a tecumseh or briggs and stratton and are less than 25 bucks normally. Get one, screw it on, wire it and rreplace the spark plug. Then, check to be sure the shut off wire isn't shorted to metal anywhere, it it is, the mower will still not start. tape it or reconnect it correctly to fix. The coil is under the crankcase cover. Oh, btw, the coil needs to be mounted the correct distance from the flywheel if you never seen one before. Try to line up or mark the old one before loosening it. Some coild only mount in one location so this may not matter.

Reply to
Marc Belanger

replying to JWitherspoon, Marc Belanger wrote: he said it will only run again when cold. Mine is doing the same thing as his, it is the coil. when it gets warm, the coil opens and doesn't give spark. When it cools back down, the coil fires the spark plug. it won't even sputter when it gets warm, when cold, starts right up everytime

Reply to
Marc Belanger

Don't people look at the dates of postings?????????????????????????????

Reply to
hrhofmann

Less than 1 chance in 10,000,000 of THAT being the problem. Spark plugs and infewrnal combustion engines don't quite work that way.

Again you are picking at straws - with something perhaps in the nieghborhood of a 1 in 5,000,000 chance.

Now you are gettind somewhere close to the realm of possibility - and even probability. The coils have solid state components in them that can fail from heat and vibration. The FIRST thing to do is remove the shroud and blow all the chaff and weed seeds out of the cooling fins to make sure the engine is cooling..Re assemble the engine - run it 'till it quits, pull the plug wire and hold the end of the wire while someone gives the rope a quick pull. If your eyes don't light up, you KNOW it is a spark problem.

Generally, if the coil is loose it will hit the flywheel and it is more likely to have a problem starting cold than hot.

Why not check that first, and quite possibly save yourself 25 bucks??

And in many cases (all older tecumsehs ) under the flywheel too.

On a Briggs (external mounted coil) a peice of cigarette package cardboard or a business card is "close enough for government work".

Reply to
clare

Then why did you send him on the wild-goose chase about the mythical hot fouling plug, hot-failing plug wire, and heat sensitive loose coil mounting???? On electronic ignition mower engines it is almost always the coil - except on those rare engines with a separate ignitor - where the ignitor itself may be bad and the coil still good (although USUALLY it is a bad coil that kills the ignitor module). On older point ignition engines it CAN be a bad capacitor (condensor) or a bad coil.

Reply to
clare

Some do, some don't. Why?

Reply to
Red

Geeeze,

the guy has been through 2 new mowers and maybe even a new wife by now.

Reply to
makolber

replying to Sherman, mowerboy wrote: My mower was doing the same thing but I fixed it it turned out to be my control cable it was just unnoticeable loose from years of fair wear and tear a new cable fixed my instantly

Reply to
mowerboy

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