2017 Engine "Knock" (vids)
Fleet Mechanic
Joined: Apr 2015
Posts: 1,641
Likes: 507
From: Phelan CA
I've definitely been meaning to do just that DSLTRK, we've been busy Mustang shopping. I would agree that the conditions would make one lean toward exhaust manifold leak, but it's definitely a knock from the bottom, center of the engine and not from one side or the other, but sounds do odd things so I wouldn't rule anything out just yet. Was relieved that I couldn't feel the knocking what so ever. Will report back, may dry out enough today to get back under there and check.
Somewhat of a similar story. I had a 2.3l Ranger have the knocking sound when warmed up. Sound seemed to be coming from the top rear of the engine.
Used the stethoscope method and it turned out to be the rear alternator bearing going.
5th Wheeling
Joined: Aug 2017
Posts: 38
Likes: 3
If it's intermittent, it is not a rod knock or wrist pin. I still think it's an exhaust leak because you state it comes on when warmed up. Metals often expand enough to open up gaps between the gaskets when the engine is at operating temp.
I can almost bet your oil analysis will come back squeaky clean.
I can almost bet your oil analysis will come back squeaky clean.
Thread Starter
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Tuned
Joined: Oct 2018
Posts: 410
Likes: 33
Every exhaust leak I have heard has had a distinct tick, like a loose spark plug bleeding compression. They can come and go though too, but I'd place good money it it not being an exhaust leak. Will get under there ASAP, but won't be this evening.
5th Wheeling
Joined: Aug 2017
Posts: 38
Likes: 3
Please let us know if you find anything. I was actually underneath mine yesterday trying to locate the source to no avail. Mines been doing it intermittently for about 10K miles and has not gotten worse. The oil analysis put my mind at ease a bit but the noise still concerns me somewhat. I'm thinking it may have something to do with the cam phasers as the oil pressure changes when the idle bottoms out. My wife's 4runner (OHCs) makes a similar noise under similar circumstances and the internet lore on those engines says it's completely normal valvetrain noise.
5th Wheeling
Joined: Aug 2017
Posts: 38
Likes: 3
Yep..mine sounds like that. Just not as loud or as pronounced as that video. Same frequency and tone.
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Postmaster
Joined: Aug 2015
Posts: 3,146
Likes: 32
From: Maryville, TN
Would you please stop ignoring Rvpuller!
He is more than likely right, it's just belt slap, hence the reason you only have the problem at idle. While it's not a common thing, it's not abnormal for the belt tensioners to go bad on these things fairly early. Spend 2 minutes taking the belt off, start the truck, see that your problem is gone, spend 5 minutes putting the belt back on, then you can confidently report the problem to your dealer for a 1 hour service session while you mustang shop.
He is more than likely right, it's just belt slap, hence the reason you only have the problem at idle. While it's not a common thing, it's not abnormal for the belt tensioners to go bad on these things fairly early. Spend 2 minutes taking the belt off, start the truck, see that your problem is gone, spend 5 minutes putting the belt back on, then you can confidently report the problem to your dealer for a 1 hour service session while you mustang shop.
Trailering
Joined: Oct 2010
Posts: 24
Likes: 1
From: Jupiter, Florida
Add me to the list of low RPM knocking. I watched those videos a few weeks ago and could not hear what the OP was describing. Now that I noticed my truck is doing it, I distinctly hear it in those videos. Raising the RPM would probably solve the issue. I wonder if there is a Forscan setting for increasing idle speed.
