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Old 10-21-2007, 12:38 AM   post #1 of 15
kwwolfe
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Default Sick GT235..Need HELP!!!

Last time I ran the tractor, it seemed fine. The only thing that I have done since then is used compressed air to get rid of some grass around the engine and what looks to be an old mouse nest. I bought this tractor used about 4 months ago, and it has worked great so far.

Now for the problem. When running, it now makes rythmic popping (bup bup bup bup POP, bup bup bup bup POP) sounds, like the compression is getting built up, and then is released. It is blowing black smoke (unburned fuel I guess).

I replaced both spark plugs. The old ones were convered in black sute. Nothing different.

The air filter is clean. I removed it and looked at the choke plate. It is moving freely as it should. I then started the tractor without the air filter on. It is blowing smoke and fuel back through the choke plate (air intake I assume).

I then removed the exhaust and blew air through it. Does not seem to be clogged. Air goes in one end and comes out the other just fine. I didn't try running it without the exhaust on for fear that I would wake the neighbors, and make myselof deaf since I was working in the shed.

I need help bad.
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Old 10-21-2007, 02:42 AM   post #2 of 15
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Default Re: Sick GT235..Need HELP!!!

Sounds like the valves need adjusting, like the lash is too close. Or at the other extreme, way to loose.
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Old 10-21-2007, 04:33 AM   post #3 of 15
HydroHarold
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Default Re: Sick GT235..Need HELP!!!

First, tractor was running fine.

Second, compressed air was blown all over (into?) engine crevices?

Sounds like too much compressed air into a tender carburetor area.... Naw... But check into the carb intake for a dead mouse or something else stuffed in there.

White smoke indicates: Oil burning or fuel NOT burning.

Black smoke and sooty plugs indicate: VERY rich mixture, too much gas-not enough air. (Thinking out loud so far...)

And then there's that "#&&@** mouse nest"... I'd run down every wire having to do with "ignition", especially primary wires (12volts) and see if there isn't an intermittent open/broken wire. Mickey loves wire insulation and will chew right through wires. Now I'm guessing electric here as you say you've already checked the intake of the carb for obstructions? AND the air cleaner is not blocked.

Also check to see the choke butterfly plates are opening all the way after the engine is running... AND that the float in the carburetor is behaving (NOT pinholed and sunk down in the bowl). IF there's a "main jet" adjustment screw see that it's not been inadvertantly spun out (rich mixture).

Anybody else?
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Old 10-21-2007, 07:32 AM   post #4 of 15
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Default Re: Sick GT235..Need HELP!!!

"OTHER'S" little 12 horse Briggs had similar symptoms the day I forgot to tighten the dip stick after checking oil level. It seems as if the crankcase ventilation system is rather touchy.

Possibly a vent hose or something in that area was displaced with the compressed air? Maybar
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Old 10-21-2007, 08:09 AM   post #5 of 15
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Default Re: Sick GT235..Need HELP!!!

Maybe thats why they call them Johnny Poppers slkpk
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Old 10-21-2007, 09:12 AM   post #6 of 15
kwwolfe
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Default Re: Sick GT235..Need HELP!!!

RED,
Could a valve go out of adjustment that quickly and due to compressed air? The tractor was running fine last time. Now it will not rev past half way. I should also mention that running like it does, it shuts right off at the first touch of the choke.

Hydro,
The smoke is black. Sute on the plugs. I took off the air filter and the choke plate is clean and un abstructed. When I ran the tractor without the airfilter on, you could see mist and smoke coming back through the choke plate.

I guess I might have to remove the air filter plate and look at the carb itself. Any hints that might be helpful. This will be my first time with this tractor. I took the carb off a 78 Cub 1250 once. That about sums up my mechanical experience. Thanks for the help guys.
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Old 10-21-2007, 11:32 AM   post #7 of 15
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Default Re: Sick GT235..Need HELP!!!

Sometimes things like that show up when you have done something like blowing the engine off and it really has nothing to do with what you did. From the sound of it you must have a stuck needle valve or the float may have a pin hole in it to be getting that much fuel in the engine. I guess it is a testament to those Vanguards that it can burn that much fuel, putting the choke on just puts it over the top as to what it can burn. I would try tapping lightly on the carb body with the handle of a screw driver before doing anything else to see if the float/needle valve may be stuck. The mixture screw is on the top side of the carb and should have one of those emissions caps on it so that may not be the prob but who knows. Either way it sure sounds like a sick carb given your troubleshooting so far.
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Old 10-21-2007, 04:13 PM   post #8 of 15
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Default Re: Sick GT235..Need HELP!!!

Sooty plugs sure sounds like too much fuel. Is the vapor you see at the choke plates caused by backfiring? Is it popping back through the carb? If yes, check on a hanging intake valve but run all the fuel checks and wiring checks first.

Another check you can do to see if it's getting too much fuel, disconnect the fuel line or shut off the fuel as the engine is running. If it starts to even out and run better before it stalls... it's carb/mixture problem... I'm officially voting "Carb Float Problem" at this point.

As far as your mechanical knowledge goes... you already know more than you did before this happened! You'll git 'er!
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Old 10-21-2007, 09:57 PM   post #9 of 15
kwwolfe
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Default Re: Sick GT235..Need HELP!!!

Harold,
I will try and run the test you suggested. Last time I ran the tractor, it did appear that something is coming back through the carb plate. If it is a stuck intake valve, is there a simple way to fix, this, or am I goign to have to start disassembling things. My brother in law gave me a can of car cleaner. Would spraying that in help any? How about a hammer?
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Old 10-22-2007, 12:35 PM   post #10 of 15
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Default Re: Sick GT235..Need HELP!!!

If your going to use a hammer.... use a big one and we want pics of during and after..
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Old 10-22-2007, 04:20 PM   post #11 of 15
kwwolfe
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Default Re: Sick GT235..Need HELP!!!

Talked to a guy here at work who builds pullers. His thought was either lose spark plug wire, or sticky exhaust valve. I will try and look into the spark plug option tonight. Hopefully it is only a loose wire. I don't know #$*%&$ about sticky valves.
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Old 10-22-2007, 11:02 PM   post #12 of 15
HydroHarold
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Default Re: Sick GT235..Need HELP!!!

Like I said, check ALL the ignition wires, low and high voltage. An intermittant open in the low voltage will act just like a plug wire failure.

Both plugs sooty indicate (to me) it's not one exhaust valve fouling two cylinders. Way too much unburned gas in there. I'm still going with too much fuel in the mixture. Maybe carb internal gasket failure, sunken float, bad jet setting due to adjusting with dirt in jet and the dirt working out...

Now I REALLY REALLY want to know what turns up!
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Old 10-23-2007, 12:37 AM   post #13 of 15
kwwolfe
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Default Re: Sick GT235..Need HELP!!!

Like I said, I am not a mechanic however I think I threw a rod. The guy I know at work suggested that I take out the spark plugs, connect them the wires and set them against the engine. Then crank it once to see if there is spark. Yep..both had spark. I was hoping for loose connection, but nope.

I was afraid to take off the head cover, but he reasured me that I could not do any harm, and that I should probably replace the gaskets anyway so....what the heck. Looking straight at the tractor, I took off the right cylinder cover. Back to the tractor and turned it over very briefinly (on ihs recommendation). Sure enough, only one valve going up and down. Took a closer look and this is what I pulled. This is supposed to be straight right? Well I pulled the other head cover to just to make sure. Yep, should be straight.

Now all I have to do is get another one and figure out how to reinstall it. What else do I need to know?
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Old 10-23-2007, 08:28 AM   post #14 of 15
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Question Re: Sick GT235..Need HELP!!!

Quote:
Originally Posted by kwwolfe View Post
Like I said, I am not a mechanic however I think I threw a rod. The guy I know at work suggested that I take out the spark plugs, connect them the wires and set them against the engine. Then crank it once to see if there is spark. Yep..both had spark. I was hoping for loose connection, but nope.

I was afraid to take off the head cover, but he reasured me that I could not do any harm, and that I should probably replace the gaskets anyway so....what the heck. Looking straight at the tractor, I took off the right cylinder cover. Back to the tractor and turned it over very briefinly (on ihs recommendation). Sure enough, only one valve going up and down. Took a closer look and this is what I pulled. This is supposed to be straight right? Well I pulled the other head cover to just to make sure. Yep, should be straight.

Now all I have to do is get another one and figure out how to reinstall it. What else do I need to know?

MMMphh--Bent push rod---maybe fell out of the rocker arm--but how?
I had one fall out on a Kohler Command series single cylinder , but did no harm--just turned the engine over -stuck it back in place.

Puzzling why it would just show up after air-blowing the motor off...????
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Old 10-23-2007, 09:01 AM   post #15 of 15
kwwolfe
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Default Re: Sick GT235..Need HELP!!!

glenn, "Puzzling why it would just show up after air-blowing the motor off...????"
You got me. I suspect it had nothing to do with the air. Maybe just bad timing. While I am fixing this, I am also going to pull of the heads, check the cyclinder and walls, clean the valves and valve ports, and put new gaskets on.

I saw carbon around the exhaust valve so I figured I might as well clean things up and makes sure everything else is OK while I have the head off anyway. Anyone have any suggestions on what to clean the valves with, or how to do it?
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