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300 I6 idle speed/valve noise

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Old 03-16-2018, 03:32 PM
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300 I6 idle speed/valve noise

Engine is making a lot of valve noise (has since I first fired it up) and I’m hoping to get some info on that.
It seems awful loud but on other videos of I6s people always comment “sounds like a diesel“ so maybe it’s common.
Note: exhaust is gutted and glass packed so some of the noise heard is exhaust. Not sure how much of an effect that has but info is info I guess.

Also, could anyone happen to hear the idle and tell me if it sounds ok speed wise? I don’t have a tach and am just winging it and thought someone might chime in.

Vacuum gauge came today so I can adjust my mix. Would this also help me find a proper idle speed?
Could I request the steps to tune a carb with a vacuum gauge?

I posted in the inline 6 forum as well
 
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Old 03-16-2018, 08:42 PM
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What is the oil pressure while ideling? I'm conserned about a collapsed lifter at idle. Does the noise go away at 1200 rpms?
 
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Old 03-17-2018, 07:28 AM
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Oil pressure gauge shows above half way at idle

it is near impossible to tell if the noise still happens above idle because of the exhaust noise but it does seem to smooth out some.
 
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Old 03-17-2018, 08:56 AM
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Is this a rebuilt engine, where did it come from? I would pull the valve cover, turn the engine by hand to see rockers are installed completely. See if oil has been pumped to the rocker and see if the cam is moving the push rods. We need as much information as you can get us. And I am going to be away for a while.
 
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Old 03-17-2018, 09:08 AM
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I’ll see what I can do about opening up the valvetrain.

History of the truck is a little botched but here’s what I know. My grandfather bought it in 2003 title says he paid $100 for it. He never did a thing to it and let it sit under an overhang of the barn in the weather for 15 years. Maybe drove it once every 5 years around the yard, it would stall, and he would limp it back to the overhang. I’m assuming that since he paid 100 for it it probably wasn’t perfect to begin with. No rebuild, all I’ve done is freshen up the fuel system and the ignition system. Oil pressure takes about 10 seconds to climb above half way according to the oil gauge but we all know how that goes. He never works on his cars he just feeds them gas and oil. Whatever the Previous owner told him 15 years ago I’m sure he doesn’t remember now.
 
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Old 03-17-2018, 11:34 AM
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In dash gauge notoriously in accurate. Get a good mechanical gauge on the engine to verify pressure.
I've been under the hood of hundreds of these trucks over the years and some 300s are just noisy, some are smooth as glass, but mostly noisy
 
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Old 03-17-2018, 11:17 PM
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What they said of course. But in the video it just sounds like standard exhaust leakage noises to me.
Cracked exhaust manifold (usually on the back where you can't see it!)
Leaking transition/collector gasket/seal.
Rusted out holes in any part of the tubing ahead of the muffler (too loud and distinct in the video for it to be farther back I would think).
Old oil? Even with so few miles, if this is the oil that was in it 15 years ago, and there's no way to know if the PO even changed it at that point, it's way beyond time to change it!

Probably more stuff too (vacuum leaks for one), but that's a big enough list for now.

Paul
 
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