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beuce

Engine Advice (Pictures Added)

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beuce
The 16 horse briggs in my T-16 sounds ok at idle but at full throttle it sounds like it is knocking. Also the knocking seems to get louder (or more pronounced) as the engine heats up. I am hoping someone here can give me some advice on the symptoms and remedy. I wonder if it could be something like an exhaust lifter that heats up and starts tapping the head, or a loose crank, or?, I guess I don't know where to start.

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dirtsaver
Brian I hate to bring bad news but sounds like maybe the wrist pin may be loose and slapping or the rod may be loose on the crank. Any way you look at it you need to break the engine down and check it out while there's still a chance to save it.

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roma3112
Brian Hopefully you have a spare tractor like some of us, because if i were you i would take that old girl apart before somthing major grenades inside. These cast iron engines are more and more expensive to fix and the people with used ones usually get a good bit of money for one, so if you have the skill I would definitely reccomend tearing it down and finding the problem. good luck john

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BLT
Before you do anything drastic, remove the cylinder head and check for carbon buld up on the fire deck. If you have an impression of the piston embedded in the carbon, that is a souce of rod knocking. Clean that out first and then run it. I am assumming that there is no other problems.

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patrician12
First thing to do is stop using it and pull it apart.The crank is steel and the rod aluminum.Rarely does the crank wear,the aluminum naturally wears first however if you let the rod go into orbit like a speeding bullet it will destroy the crank.Right now you are looking at $200.00 in parts.Piston,rings,rod and head and pan gasket.A short block of this motor is $900.00 so invest the money before it is destroyed.

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beuce
Larry and John, I shut it down when I decided the "knock" was probably engine noise. I do have a spare tractor, but I need to put some parts back on before I can mow with it, shouldn't be a big deal though. Bob, I am hoping it is just carbon, maybe something to do with the exhaust lifter, being it seems to get more pronounced as it heats up. It seems like the "knocking" is more in the lower part though, so I don't know at this point. The engine seems to run strong, other than a puff of smoke at start up or when I put it to full throttle. Thanks for the replies.

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MarkM1958
It would be a whole lot cheaper to rebuild it NOW and save the money of a new engine!!! Even if you have to pay the neighbors kid a few dollars to mow for you a time or two.

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firefoxz1
I agree with the concesses(sp) here. Tear it apart now before it costs you more later. I believe if it is a valve problem they usually get quiter as it heats up and the clearance shrinks (not sure), I redid an engine and made the clearance a little big on the exhaust and it clicked till it warmed up (live and learn it's to easy to take off to much, I go much slower now). Checking the carbon build up is a start but be prepared to yank it out.

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RedbarnRick
Before you tear your engine apart check out the BGB end of the drive shaft if the set screw gets loose it wears the yoke out and what sounds like a rod knock will start at about half throttle, this drove me nuts on my soveriegn until I replaced the yoke and the spacers. It's worth a looksee before you tear your engine apart

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beuce
I pulled the head and there was quite a bit of carbon build up, but as I turned the crank I could still hear a slight knocking sound, so I yanked out the engine. The piston is oversized .20 over and scored on the valve side right above the top ring on the side for about 3 inches. Not sure whats up with that. I can still see the cross hatch in the cylinder bore. The wrist pin has a slight wobble in the rod, not sure how much if any should be there. The rod has a number of .30. stamped verticle on the side but no other numbers. The piston has 211748 stamped inside on the skirt. So should I mic the bore and see what it comes out as? I am assuming at the least I will need piston, rings and rod? (Tried to post pics, but my computer is being stupid ;)) Rick, I will check out the yoke when I reassemble the tractor, thanks for the heads up...

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BLT
Briggs never made any mark to indicate an undersize rod. Their only undersize rod is .020. I am curious where the piston scoring was, exhaust or intake valve side. Also take off cylinder air baffle to see is any debris is lodged in the fins.

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