I've been dealing with lots of issues with my truck but one that keeps coming up randomly is a possible timing chain tensioner rattle. My truck is a 08 Ranger xlt 4.0l 4x4. Truck had bad timing chains when I bought it at 302,000km and had a timing chain snap at 305,000km. Bought a 09 4.0l that had fresh timing chains and guides and tensioners with all new hardware, gaskets etc. Never ran with the new parts till I put it in my truck myself. Primed the engine with oil before first start and its only ever "rattled" when it's sat for a few days. Never rattled once this winter at -30c or -40c but seems to have a very short start up rattle anything close to 0c or warmer but happens very hit and miss. Never rattles after I've had it running and start it up later in the day. Hard to explain.... only once has it rattled when warm. I was at the dump and shut it off, unloaded garbage, started it and then it rattled for the longest it ever has, about 5 seconds. But apart of me feels like it could be something else like an exhaust leak or injector issues or valve noise? It's been driving me crazy, does it sound like timing chain related? If you need anymore info just let me know, only I work on my vehicles so bear with me. I'm willing to try and learn what I don't know

 

Every time I start mine (same engine as you), I employ the "Clear Flooded Engine Method".
First start of the day or after a long shut down
1. Turn the ignition on (dash lights up)
2. Fully depress the accelerator. This turns off fuel delivery and spark too, I think.
3. Turn the key to start for 4 seconds. This pumps the oil. Release the key.
4. Then start as normal. You'll hear no rattle....or way less rattle.

I learned this here and it's what I do.

 

Yes I have done that afew times, if I remember correctly it still had the "rattle" noise on afew of the oil primed startups.

 

Did the rebuilder use Motorcraft parts? I think I read that we should avoid the aftermarket tensioners.
Try a thicker oil?

 

It was a mix of Motorcraft and a kit off Amazon. I tried finding some Motorcraft tensioners but the dealer didn't even have a rear tensioner in their system, they thought I didn't know what I was talking about. I've been adding some Lucas oil to hopefully help the oil stick to things a little better but honestly not sure if it's been helping at all. As far as thicker oil I've read mixed things online about doing that. Currently using 5w30, now that spring is here maybe I should try 10w30? I've also come across adding a oil line to pre prime the tensioners, but I don't have enough information on it to tackle the job. Anybody out there have any details about doing that?

 

"I've also come across adding a oil line to pre prime the tensioners", Never heard of that....sounds overly involved (complex & expensive)

At 302k km (189k mi.) the plastic guides might have perished and you might have noise.

Lots of "rattle chat" in your first post.

See how it goes.....Summer? try 15W-40 (cheap jug oil)

Get back to us and use fewer words.