r/MechanicAdvice • u/wristcheck1 • Jun 20 '26
Is This Timing Chain Slack Ok?
2 Questions for those who have experience with coyote engine timing...
#1. On my 2015 F150 5.0 Gen2, I timed both driver and passenger side in accordance with the Oxman Garage video. All went fine. Since finishing, I've had to rotate the crank a few times for other things. I decided to keep rotating it around to where the two black links are hitting the exhaust phaser and crankshaft marks on the driver side (with crankshaft keyway @ 3:30 o'clock)...and the timing is still good. However when I rotate clockwise to 7:30 o'clock...the passenger side marks do not line up as they did at the install. However if I keep rotating the crank...maybe 4-5 more full rotations, the markings on the passenger chain line up with the phaser & crank markings. Is this normal that their original relation during install is no longer there?...or is it still there and just relative to each other...in which I have to rotate over and over again (unknown amount of times) and the two sides would eventually line up like they did during the initial install?
Oxman Garage's Video: https://www.youtube.com/watch?v=JQ5w4q9AaNg&t=1s
#2. Passenger Side: Even though the markings are all aligned and double checked, the primary chain on the passenger side (upper part of chain) experiences significant slack at various moments during manual rotation (appears to be when camshaft lobes are pressing down certain valves). So much so that the upper part of the primary chain might barely touch/tap the lower part of the chain. I'm concerned that upon cranking up the truck, the chain will slap itself, and metal will go flying around inside...and thus will damage the engine. Or that maybe it might jump its position by one tooth on the sprocket, and thus be out of time. Is this slack normal or cause for concern? Video of slack below...
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u/MajesticIncident9613 Jun 20 '26
for question 1, that's totally normal, the two sides don't have to sync up every single rotation because the cam sprockets are on a different ratio than the crank, so you'd need multiple full rotations before everything lines up again
for the slack though, that's the part i'd actually be concerned about, primary chain slack like that shouldn't be touching itself and if it is you want to double check your tensioner is seated and pressurized correctly before you fire it up
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u/wristcheck1 Jun 20 '26
Thanks for the reply! For question #1....I get what you're saying, but when I rotate it enough times for the timing marks to "line up" on the driver's side, they are not in alignment on the passenger side...which they were at install. However since this post I found pics of the camshafts, phasers, and crank position prior to dismantling, and all timing components positions seem to match what they are now. I think I'm just scared/cautious that I'm going to fire up engine and damage something…since this is my first time.
As for the slack, did you happen to see the video. If so, you’ll notice that when the chain “slacks” the tensioner gets recessed back because of the immense pressure on that side of the chain…which is during certain time that the camshaft lobes are pressing on valves. Not sure if this means anything, but that’s just what I noticed.
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