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IronPony

Head Bolts

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IronPony
I have a AC712 with the Kohler 16hp K341 series motor. I replaced the head gasket and now find that I need to keep checking the head bolts to make sure they stay torqued down. 1)Is it normal for the head bolts to lossen up? 2) Is there any standard on wheather I should tighten them while the motor is hot or cold. Any advantage to either hot or cold?? Dan

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BLT
Dan, it wouldn't hurt to clean the threaded holes with a bottoming tap. Over the years the holes tend to collect debris from rust and what have you. That can also alter the bolt torquing.

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BillC
Not only should you clean the threaded holes in the block with a tap but I also strongly recommend looking at the cylinder head torque procedure in a Kohler service manual. For example B&S states graphite grease should be used on the cylinder head screws.

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HubbardRA
When I remove a head, I retap the holes to clean them, and also run a die down the threads on the bolt. Most times is put a couple drops of Kroil on the bolt threads and torque them down. Never had any to loosen up.

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Al
Hi, When you do the bolts, be sure to wire wheel them, and run a tap in the holes and blow them good. Check the head for flatness. If you can run a 002 feeler guage under the straightedge, resurface them. You can do this by getting a flat plate. A ground surface on a steel plate, or something like the flat on a ground top table saw. Put some 80 grit granet paper on it grit up. Take the head and slide it back and forth, rotate it 1/4 turn every stroke or it may not come out flat. Keep taking metal off until you see clean cut metal all over. When you start you will only see sanding marks where the bolts tighten down. This is because this is distorted down by the bolt heads. As you continue as the high spots are removed the marks will spread out until they meet. Then take a sheet of 120 grit and give it a few strokes as above. THEN WASH WITH HOT SOAP AND WATER. Next put a thin film of anti-sieze, graphite grease, Briggs valve stem lube, or a little oil. Put the oil on the bolt and let it drip off. DO NOT PUT OIL IN THE HOLES Put it together and torque it in 2 or 3 stages in the sequence the engine mfr calls out. Run it for an hour or 2 and then with it warmed up retorque them and you should be good to go. Even it it doesn't get retorqued you shouldn't have any more trouble. Note: Be sure you have the origninal type thick washers and not plain washers. We have to do almost every head we remove from the new OHV engines. However it seems that once they have adopted the original warpage and they are resurfaced they stay good from then on. The new Big Kohler OHV engines the head gaskets now come with new head bolts and you have to throw away the old ones. The new ones are Torque to yield as are most in the newer cars and they cannot be reused. They are actually tightened to the point where the molecules are at the separation point. My 2 cents worth and its free, value accordingly. Al Eden

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