The 3.5L EcoBoost is great engine with a few problematic complaints as of late. These engine that comes buried inside the F150, Explorers, and the Taurus SHO has been seeing a little growing pains concerning the timing chain. I mean that statement very literally - the timing chains are stretching causing all sorts of problems. A stretching chain starts out to cause a few drivability issues, maybe a little bit of noise, then escalates into a full blown tear-down due to bent valves. I love these 3.5L EcoBoost engines, but this is definitely an issue.
Have no fear though, as this problem can be remedied with a new timing chain. I can't say for sure that a new chain won't stretch again, but it will for sure fix your issues in the meantime. I should elaborate a bit on the chain failures. The 3.5L EcoBoost chain doen't actually stretch, because elasticity is not a property of metal. The chain actually just wears out at all of the pivot points for each link, likely because the way the chain is routed causing it to bend completely backwards as it travels along the water pump / center idler.A small amount of wear, multiplied for every link, creates a chain that is longer than intended.
Changing the timing chain on a 3.5L Ecoboost isn't nearly as bad as you might think. Even with the twin turbo engine having an impressive three timing chains, three chain tensioners, four chain guides, four camshafts, and 24 front cover bolts - at least the front cover area is rather open and easily accessible on the F150. I feel sorry for you Taurus, Explorer guys. Either way, many dealer techs prefer to drop the sub-frame on Taurus and Explorer models, and raise the cab on F150's but it is not required.
Eventually, I will divide this article up into a few pages explaining removal procedures for each model. There are going to be a few tools you will need to complete a task like changing your timing chain. A basic selection of tools will get the job done along with the addition of a few specialty tools.
Camshaft Timing Tools
3 Jaw Harmonic Balancer remover
Torx Plus TP55 **Must be TORX PLUS not regular TORX**
The Torx Plus socket is used for removal of the camshaft sprocket bolts. It is very different from a regular Torx socket. The use of the wrong tool will likely strip the bolt head out leaving you with a pretty significant issue. The puller is pretty standard to remove the harmonic balancer, noting that some pullers don't work with this balancer but I have confirmed the one I linked to does in fact work, and the camshaft holding tool holds the cams in the right spot for setting the chains. Obviously using the correct tools makes the job easier, the job can be done without the timing tools. However, because the tools are so cheap now, I highly recommend just buying a set because it makes life so much easier.
Be sure you know which bank is which. The "left" bank is the one that is on the drivers side or on the front of the engine in a front wheel drive application. Always think of it as if you were sitting in the drivers seat looking forward out of the window. This is always the way you consider left/right parts on the vehicle. Sometimes it is easier to say "drivers side" or "passengers side".
You should replace other parts while you're in there, in my opinion. Other parts such as the timing chain guides, timing chain tensioner, vct phasers, and so on. Remember you will also need all the applicable gaskets. Now, onwards to the step by step on how to change your Ecoboost timing chain.