Constant tick -- not ping, not a knock...

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that_slow83
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Constant tick -- not ping, not a knock...

Post #1 by that_slow83 » Fri Sep 14, 2018 3:25 pm

Hey guys!
I have a 1983 F-150 with a 300 inline six, with the standard 1v carburetor (rebuilt), stock intake and exhaust manifolds, no cat, and no air pump.

The truck has been making a cyclic noise that sounds a bit like a tick or an exhaust manifold leak -- It's not deep enough or harsh enough to be a knock (thank god). If anything, it sounds like top end chatter from just one cylinder out of six. Just enough to throw off the smooth note that a straight six usually has. The noise is always there, whether the engine is cold or hot, under load or decelerating, or simply just idling.

-- I have run Rislone engine treatment and Marvel Mystery Oil, both with no changes to the sound. I changed the distributor cap, which improved overall sound, but didn't affect the tick.

I have had the valve cover and side cover off before. The rockers all looked good and all valves were opening, but the exhaust rocker on cylinder 5 didn't have much oil. The push-rods all looked okay from the side, but I didn't run the engine without the side cover installed. I have hydraulic lifters, so I **shouldn't** need to adjust my valve clearance.

I know these are notoriously tough engines, but I want to fix the tick in case it's causing damage. It gives me peace of mind to have a nice, smooth running engine.

To clarify, I do not believe this is detonation. I've had detonation before due to overadvanced timing, and the detonation only happened under load. This noise is constant with the engine's speed and simply gets louder when the engine is louder.

Here's some audio I recorded while I was driving (30 second clip)...
https://vocaroo.com/i/s1SHpHRBWsJ7
The audio upload site throttled my audio quality. Let me know if you can't hear the tick, I can send you the raw file.

Harte3
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Re: Constant tick -- not ping, not a knock...

Post #2 by Harte3 » Fri Sep 14, 2018 3:35 pm

That 'tick' might be an exhaust leak. Check the donut gasket between the exhaust manifold and exhaust pipe. If it is blown out, it might make a ticking noise.
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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that_slow83
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Re: Constant tick -- not ping, not a knock...

Post #3 by that_slow83 » Fri Sep 14, 2018 3:39 pm

Harte3 wrote:That 'tick' might be an exhaust leak. Check the donut gasket between the exhaust manifold and exhaust pipe. If it is blown out, it might make a ticking noise.


Thanks for the info,
I should have included in the post that I replaced the exhaust donut gasket over the summer. The old one was cracked, but the new one didn't change how it sounded.

That brings me to an interesting thought, though. When I bought the truck, the exhaust was very loud because there were holes rusted through the cat and muffler. I never heard the tick until I had the exhaust re-done.

Harte3
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Re: Constant tick -- not ping, not a knock...

Post #4 by Harte3 » Fri Sep 14, 2018 4:12 pm

Another place to look is the exhaust manifold itself and that may come with problems due to access. I had one that was cracked on the back side between the manifold and block...a real PITA to locate. It stayed that way until I did the rebuild with some mods including an Offy DP intake and the stock EFI exhaust manifolds.
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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that_slow83
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Re: Constant tick -- not ping, not a knock...

Post #5 by that_slow83 » Fri Sep 14, 2018 4:36 pm

Harte3 wrote:Another place to look is the exhaust manifold itself and that may come with problems due to access. I had one that was cracked on the back side between the manifold and block...a real PITA to locate. It stayed that way until I did the rebuild with some mods including an Offy DP intake and the stock EFI exhaust manifolds.


That's for sure a good possibility.
I found a couple weeks ago that my front-most exhaust manifold bolt was a little loose. Not sure how long it's been like that, but that could be the sign of a hidden crack.

I took a long piece of pipe recently and held it against the engine on one end and against my ear on the other. It amplified the tick a lot if I touched the engine on the head, where it went into the exhaust manifold. Would you expect an exhaust leak to be amplified by the stethoscope trick or not?

justintendo
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Re: Constant tick -- not ping, not a knock...

Post #6 by justintendo » Fri Sep 14, 2018 5:26 pm

wad a blanket or old towel up and try to temporarily seal up the tailpipe pretty tight with the truck idling...if your tick is a leak it will get louder. you will be able to do this for a few seconds before the towel gets too hot. sometimes it helps to get a friend to do the stuffing while you investigate the noise..
96 F150 rc/sb...4.9, m5od, 2.73 gears
dual electric fan, kirban fpr, modified airbox, front/rear hellwig swaybars, rancho shocks, 2" rear drop, steering damper, general grabber hts, pioneer stock size speakers/head unit, mtx 8" sub behind seat

Mdixon300f100
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Re: Constant tick -- not ping, not a knock...

Post #7 by Mdixon300f100 » Fri Sep 14, 2018 9:19 pm

My original log exhaust manifold had a hole near the linkage for the card heat. Switched to efi manifolds and it was gone. Stick your hand around ( not on) the card heat spring while running. You'll feel the leak if there's a hole.

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that_slow83
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Re: Constant tick -- not ping, not a knock...

Post #8 by that_slow83 » Sat Sep 15, 2018 3:56 pm

I tried the blanket trick and found my main pipe was loose at the flange. I could wiggle it by hand.
I tightened the flange bolts pretty good so it can't wiggle anymore, but the noise still hasn't changed at all.

I tried feeling around the spring for the exhaust flapper, but I couldn't feel any exhaust escaping there while the engine was on.

I also noticed the noise seemed to be coming from a little different place upon further inspection under the hood:
The fan seems to be making its own tick, and when you open the throttle by hand and take the engine off idle, you can hear a slightly sharper tick from near the intake manifold or engine head area.
How is the fan clutch supposed to work? I think mine may be seized, which is causing extra fan noise.

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