| ldh2176 | -- 01-03-2016 @ 1:33 PM |
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Hi everyone, I understand these v8 flatheads should run very quite. This is my first experience with a flathead and it has a knocking type noise. The engine was professionally built to factory specs. I pulled spark plug wires, took off the fan belt in case it was the water pumps, took out the fuel pump rod and pulled the engine and pan to double check the mains and rods. The knock will not go away. I checked the valves and none are hanging up. I checked the piston dome and valves for damage with nothing observed. Any thoughts? Thanks in advance.
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| cliftford | -- 01-03-2016 @ 5:28 PM |
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Is this noise occuring all the time or just at certain speeds? Has it done this since it was rebuilt of did it just recently develop? Most all these engines have some valve noise which is more of a clicking sound. With a little more info. some of us can help you.
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| ldh2176 | -- 01-03-2016 @ 5:38 PM |
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The noise is there all of the time and has been there since I first fired it.
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| MG | -- 01-03-2016 @ 5:52 PM |
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Could be a number of things. Is it a 'heavy' knock? Was the engine rebuilt recently? Could be a lifter out of adjustment or a valve spring keeper missing. Or, a broken valve spring. I'd pull the intake manifold and inspect the valve galley....
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| TomO | -- 01-04-2016 @ 8:32 AM |
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First I would try to isolate the noise by using a mechanics stethoscope or a long screwdriver held to the ear and moved around the engine. Check each cylinder by probing near the spark plug, then along the intake manifold, then along the sides of the block and finally along the oil pan. Once you know where the knock is coming from, you can start to disassemble the engine are and inspect for interference. If you still have the heads off, check for marks in the firing chamber and check for all of the valve guide keepers are fully seated.. Tom
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| Drbrown | -- 01-04-2016 @ 7:48 PM |
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The probing gets very exciting when you have the screw driver in your ear and you accidentally touch a spark plug (sorry TomO, I couldn't resist)
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| TomO | -- 01-05-2016 @ 8:16 AM |
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Drbrown, I don't like to use the Ford screwdriver for this test as the shank goes all the way through and gives you an electrifying experience, when you get close to a plug wire. I used to have red curly hair, before I tried this, now it is white and straight as an arrow. Tom
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| trjford8 | -- 01-05-2016 @ 8:37 AM |
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So that's why I've lost all my hair!
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| pauls39coupe | -- 01-05-2016 @ 8:50 AM |
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Check the clearance between the cam and crank gear teeth. Excess clearance will give you a pretty good knock. This may sound like it is at half the engine speed. If both gears were not replaced at rebuild time this may be your problem. Another possibility would be the fuel pump push rod being loose or a defective pump allowing the push rod to bounce. It will cause quite a knock. Either of these sound will echo around in a flathead, making them hard to trace without removing the fuel pump, or front cover.
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| harvsfl | -- 01-07-2016 @ 5:26 AM |
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A friends 41 had a knock and it was a cylinder sleeve hitting the head. The 41's are sleeved engines and the wrong head gasket was used. A head gasket with a smaller diameter cylinder hole was installed and the sleeve lock-tighted in. Problem solved.
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