So my 05 GT with about 65k kilometers (approx 43k miles) on it is starting to rattle for a second on start up after sitting a while. I know it is the timing chain rattling until the tensioners are activated with oil pressure, has to be that. Here are some facts:

-stock engine
-5W 20 oil, changed every 4500 kms
-proper ford filter with check valve

My 04 F150 is doing the same **** thing, might be time to replace a whole whack of timing chain tensioners and associated parts.

Thoughts?

 

I wouldn't worry about it. At 250k my F150 (4.9L 6 OHV) has had all kinds of rattles but it still drives fine. The odd thing is it has a bit of lifter clatter right after I change the oil but goes away in a few hundred miles. But its been that way for a few hundred thou...

The old saying is "better to have a little (valve train) rattle than none at all" because none at all could mean the tappet clearance was too tight and valves weren't closing all the way (= burnt valves).

Perhaps you're hearing a bit of roller follower/lash adjuster clatter rather than the chain? After all there's 24 of 'em working away. I hear my valve train a bit at idle when the hood is up and I only have 10k. Been that way since day one. I like it but I'm old school.

As for a bit of chain rattle, its not like it can skip a tooth if that's what it is.

Since it goes away under throttle (all the slack is taken up), the only other possibility I can think of is could an oil pump be getting weak? Seems like I read the 4.6 3V oil pumps have had some starving issues in race conditions. Perhaps a weakening pump isn't providing enough pressure to the "hydraulic actuated lash adjusters" (under the roller followers) at 1k rpm idle?

Finally, seems I read a thread today or yesterday that someone thought this issue could be from cam phasers? Not sure why that would cause rattle though.

 

Good info CDY...

 

Does it stop right away? Or does it stop after it warms up? If it stops after it warms up, then you could attribute the noise to the aluminum parts "shrinkage" when the car is cold and then quieting down after the car warms up and those parts expand to an acceptable tolerence. I had an Integra that did that; no big deal.

 

Great point. If I remember right, my all aluminum Lotus 907 DOHC had a difference of .002 valve clearance between being checked cold or warmed up.

 

The rattle only lasts about 1-2 seconds and goes away, so it is not the aluminum shrinkage. That would take a few minutes for the temperatures to rise and aleviate. I don't need to rev the engine to make it go away, it is gone at idle. Definately a chain tensioner issue. I have to tear my 04 F150 down to look at it (worse than my Mustang) and I suspect the Mustang not far behind. At least the cam phasers are okay.

 

One last thought - could it be the lash adjusters being pressurized?
I hear that brief thing too on my F150 where the lifters get pressurized after a second or two and then are quiet...
I would be surprised if its chain rattle. Even if it is, why tear into an engine over that?

 

What makes you think it is the tensioners?

What you are describing is very similar to a common noise heard on a lot of the 2v 4.6/5.4 engines. Some went to a Motorcraft filter to make it go away and Ford also found it to be pistons that were too small at startup and rattled until they expanded from engine heat. Neither were an engine failure issue, I also doubt they are what is causing your noise.

 

Okay, I dredged this thread up because it's happening to my GT with 85K on the clock. It only rattles for 1 or 2 seconds when it starts up from dead cold (after not driving for a day or two). There is no rattle with a warm engine.

It sounds like the chains but who knows...maybe something else? I don't want to tear the engine apart if it's just a tensioner lube issue. I'll be doing a big road trip this summer and don't want to risk a blown engine. Well, the engine is already blown since installation of the supercharger...but that's a good thing.


Anyone else deal with this? Comments much appreciated.