[bobofthenorth]

I've done a couple of them. Its not that big a deal. FordTechMakuloco is the go to guy on Youtube for instructional videos.

You'll have to remove the front cover - there's a lot of crap in the way to get to it. You probably should put in a higher volume oil pump at the same time because its oil pressure that keeps the phasers working. There's a variety of different advice on the interweb about removing valve springs to take the backlash out of the camshaft. I ignore that and put a couple vice grips on each camshaft. If you don't lock them or release the springs they absolutely will move when you take the timing chains off and then it gets a lot more complicated. These are interference engines so you absolutely can not turn them with the chains disconnected.

Makuloco will cover all this in much more detail. You should use Motorcraft phasers and you want to find ratcheting chain tensioners. The OE tensioners rely on oil pressure to hold their position. As the chain stretches they let it slap around when the engine starts and eventually that tears the plastic guides up. The whole job is not an insignificant cost - probably $2k in parts using Motorcraft phasers & chains, new Melling pump and aftermarket guides and tensioners. If you find debris behind the front cover then you should also drop the pan and clean up the crap that has settled there. You can get the pan out without pulling the engine but its a bit tricky.

There's no cam bearings on the 5.4s which seems pretty cheesy to me. The camshaft just runs in journals moulded into the head. I'm running one right now with an obscene amount of cam wear but it doesn't smoke and seems to be OK. The guideline is supposed to be if you can't catch your fingernail on the bearing surface its good to go but this one is like a rough file in there.

 

[bobofthenorth]

This leads to my next question... is it the cam gear or solenoid that is the typical point of failure? ............. but I think both sides went haywire at the same time.... do they rely on each other in some way?

The "typical" failure mode is that that the tensioners leak down allowing the chains to slap wildly until oil pressure comes up. If they're leaking that bad then they are depriving the upper oil galleries of pressure but that's more of a secondary effect. The slapping chains eventually blast the POS plastic guides into bits. If the chains are really slapping they will also grind the inside of the aluminum cover - there's reinforcing ridges on the inside that you'll see wear on if you have had bad chain slap. All that plastic and aluminum detritis ends up in the sump. It can then plug the oil pickup or the fine bits can get pumped through the oil galleys. That's why if you've got one that has failed tensioners you should also take the pan off and clean it up.

The ratcheting tensioners are held in place mechanically and only tighten further under oil pressure. That way the chains don't slap around on startup. These are ridiculously long chains - it doesn't take much slop to get them rattling around inside there.

 

[bobofthenorth]

I agree that it is unlikely to be timing/phaser related based on the symptoms you have described. If it was me I'd throw a set of VVT solenoids at it assuming you can't make it throw a code. Solenoids aren't very expensive. I expect you have checked the harness on each of them already but if not that's worth a look.

 

[bobofthenorth]

There's little tiny screens in the grooves on those solenoids. Make sure they're all intact. If they swallow a screen they can get cranky.