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Discussion Starter · #1 ·
It's a 23 horse horizontal shaft, about 300 hours. It runs with no load, but pretty much dies just turning on the blades. Spews black smoke, which I know is a fuel thing. But it also started using a quart of oil every 5 or 6 hours. Compression test shows 120 on one side, 150 on the other. Spark plugs were both sooty black, but both sides are firing. Replacing the plugs didn't help. Any ideas?
 

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Jersey Mechanic
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Blown head gasket(s) between the valve galley and combustion chamber? Would explain the use of oil and the fact that you still have decent compression.

Dan
 

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Or a crankcase full of gas. No way a Vanguard should be worn out at 300 hours. Change the oil and try running it without an air filter, it could be saturated with oil also.
 

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Discussion Starter · #5 ·
Agreed, no way it should be worn out, although it has always used a little oil. Maybe not broke in yet. :thThumbsU No gas in the crankcase but a totally saturated air filter. Running without the air filter allowed it to run better, but it's smoking like a steam engine out the air intake. The head gasket theory was my first guess also, does that still hold up? Would/could that affect both cylinders as far as fouling the plugs?
 

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Jersey Mechanic
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It is rare that BOTH head gaskets blow, but still possible, with the compression readings that you have I would pull the heads, clean the carbon, reinstall to correct torque and adjust the valves and see what that yields.

Dan
 

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The black smoke means it's running way too rich, and has probably carboned up the valves, rings, and pistons. It may well also diluted the oil, which will ruin bearings and cause it to burn the diluted oil.
Does it smoke out the intake while it's running? That would indicate an intake valve leaking or sticking - again, maybe carboned up.
It sounds like you have, at least, a carb problem making it run rich. Have you checked the choke butterfly to make sure it's opening?
 

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Discussion Starter · #8 ·
I've got it out of the tractor, will try to tear into it today. This hasn't been an ongoing problem, just started, so hopefully not to much has happened.
 

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Discussion Starter · #9 ·
And the answer is......Yep, both head gaskets. Hole between the cylinder and the oil chamber. If I had to guess, I'd say the heads were never properly torqued, couple of the bolts on each side came loose awfully easy. The repair shop said it wasn't a common problem, they didn't even have them in stock.
 

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I had many Vanguards when I had my rental business, never any HG issues. I would verify that the cooling system is clean while you're in there.
 

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Jersey Mechanic
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Before bolting that engine back together, check the heads AND block for trueness with a straight edge and feeler gauge. Your symptoms were classic head gasket, but it is VERY rare for both to blow unless it was overheated.

Dan
 
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