Startup rattle solved? VCT Solenoids
 

I have a 2006 F150 with a 5.4L and 110K on it. I've had the infamous startup rattle that happens when the truck sits more than 4 hours. It lasts 2 - 3 seconds, not loud, but definitely mechanical and goes away and all seems fine. I was pretty sure this was due to a tensioner blowout, and that I was looking at having to do the whole timing component replacement curse that so many have had to do. I had read in a post somewhere that someone had done this and it still didn't solve their startup rattle until they replaced the VCT solenoids. I thought since I was going to do that anyway, and it was fairly easy to do without removing anything, I would go ahead and replace them first and see if it did anything. Replaced with OEM VCT's and the old ones looked fine. No difference at all in the way it runs (didn't have any idle issues or stalling to begin with) or sounds once its been running. But to my surprise, my startup rattle is now gone?

Could the old VCT's been allowing a pressure leakdown that would cause the tensioners to let the chain slack to cause the rattle? I'm happy I don't need to do the timing components, but am watching carefully.

Using a good filter like the mc 820s with a good anti drain back valve form wally world is another thing . The old steel ratcheting tensioners hold pressure on chain until oil p comes up and they don't have a seal to blow out . Use some MMO to help slow clean engine . VCTs replacement is always a good thing to do first ,yes they do gum up and stick ,new ones are better .My vct changeout made it better for a few weeks but I did not try cleaning engine and passages .
Get that oil clean and change often before 5k ,don't let it get low.
Keep plugs /ignition in good shape change at 60k ,replace all boots ,learn to do hospital clean plug install .

I hate to be the 'Bubble Buster-in-Chief', but the oil sourcing the chain tensioners comes off the oil passageways to the front cam bearing. Never goes to, or through the VCT. What ever oil pressure is available in the head supplies the tensioner direct.

Attached is a good flow diagram.

Thanks for the diagram still get lost at the vct body . I knew it fed cams directly and vcts only flows to phasers . Would have been nice if they color coded it . I like seeing the returns to the crank . New rollers face the oil orifice more aimed at roller wheel .Lashs were improved also .

At 110k miles, it certainly wouldn't be terribly unusual to have beginnings of chain rattle. It's such a distinctive (marbles in a coffee can) sound, keep your ears tuned for it. Although short (2-3) second bursts of chain rattle immediately on startup isn't too destructive. Mine did it for 30 to 50k miles before I had to do a timing job at 212k.

I believe the MOST important thing for holding off a timing job is ---- not EVER let misfires develop. As chains wear and develop slack - ANY misfires will bust up chain guides and stuff goes downhill very fast from there.

Also, I believe keeping the oiling system VERY clean and fresh helps. On about every 3rd or 4th oil change, I pour in a quart of Motor Mechanic engine flush the last 30 -40 miles of the day - let it set overnight, next morning warm it up - drain & change oil and filter. (But opinions are like belly buttons. Everybody's got one, and I get pushback on this opinion).

Mine has rattled at startup like this, also. I remember the very first day I purchased my '07 back in early 2010. It had 42,994 miles on the readout. Took it home and parked it. Came back out an hour later and started it and it rattled. Did a whole bunch of research over the years and found many others doing the same thing mine does, with no adverse effects in the long term, while others basically explode. So, I just decided to run it and see what happened later on.

Surprisingly, it has been that way and still is that way today and it is currently pushing into the 160,000 mile mark now. Most recent oil analysis a couple of months ago shows the engine is in the health of a brand new engine, based on wear rates. Weird thing is, it does it only intermittently. I can let it sit for 2+ days and start it; no rattle. But, I can let it sit for 30 minutes to an hour and start it and an obvious rattle happens for about maybe a second. I honestly think it's lifters making noise on mine. Still pulls the same 18 MPG in town and 21 highway that it was getting almost 9 years ago.

Never have changed any parts out on mine. Still extremely quiet too. I'm not really sure what's causing the noise on mine, but definitely doesn't seem like it's the chain for it to be doing it this long with nothing changing. These 5.4 3v engines are weird.

Hey I have a theory. (Not the least surprising thing for me, huh?). I think the intermittent thing is a function of where the engine happens to stop during shutdown. You know how strong valve springs (probably on the double intake valve springs) can fight the chain when guys start putting timing chains on. - Sometimes on one side, then sometimes the complaint is on the other bank. If the engine comes to rest in one of those precious spots, the constant tension - I think - would push the oil out of the best of (non-ratcheting) tensioners. So the chain would be looser on startup one time, maybe not so much another. Also the effect would be worse on the side with the leakiest tensioner.

But I agree with you - the short rattle noise is not terribly destructive. Just an indicator to watch out for other things the symptom can lead to.

That's a very interesting and plausible theory. I've never actually thought about that. That could definitely be the cause. I'm hoping it never leads to anything. So far, it doesn't seem to be affected in any harmful way and my most recent oil analysis corroborates that. I'm not sure if you're familiar with these charts, but in case you are; Here's my most recent oil report attached below, in case you'd like to take a look.

https://cimg5.ibsrv.net/gimg/www.for...ae55508ecd.png

Comparison to what I read in this report, your engine markers all show excellent health. Like the closing comment atop your report -- 'keep up the good work'.

http://www.synmaxperformancelubrican...le_Reports.pdf

'08 Lariat 5.4L

Can't say that I have heard rattling under the hood on startup, but I do hear a rattling sound from underneath the truck on startup. All I could think of was maybe some small bits in the exhaust rattling around like in the muffler or something. I have not had someone start it with me underneath so I have not made a serious attempt to ID the issue. Could this be the same rattle you folks are talking about?