Trying to track down info
My brother and his wife have a bone stock 2005 Mustang GT with 25 thousand miles

recently after the car has sat for a few hours or overnight, they go to start it and there is a horrible clattering/rattling noise liek the top of the engine has no oil.... by a two-count, it subsides.... scared the CRAP out of them the first time it happened.

I have found no TSBs related to this and he is trying to make an appointment to take in for service....

Does this sound like a symptom of an oil pump going bad?

(oil changed religiously every 3K and using Motorcraft synthetic)

 

If the oil has been checked and is full, it sure sounds like somethings gone seriously wrong, such as perhaps an oil pump failure. Sounds like the pump itself is working but it's losing the prime. There may be engine damage being done during the initial startup with no pressure. Definitely a dealer issue. Good luck.

 

chatter at start-up might be related to vct phaser. My car chattered about 2 times, had 2 dealers check it out, but they found nothing wrong.

 

I may be wrong, but the phaser bolt issue was for a warm engine. I had to have it replaced on my '05 GT because of a "tick" when the engine was warm.

 

Yeah I know about that TSB and this has nothing to do with the cam phaser issue...............

 

Did you by any chance use other than a Motorcraft FL-820S filter? Many of the aftermarket filters do not have correct or any anti-drainback valves and will cause exactly this symptom on the mod motors.

 

I have exactly the same problem. After 4-6 hours the valve train rattles terribly when the engine is started. As soon as the oil pressure comes up, it's all normal again. This problem started soon after the 15k oil change.

The oil filter is the correct Motorcraft 820-S model (changed by the dealer), so I'm assuming it cannot be the anti-drainback valve.

I'm wondering if it is simply a loose lifter that drains down after several hours. The noise itself must the the cam follower having too much clearance which the hydraulic lifter takes up as soon as the oil pressure comes up.

I'm interested to hear others have the same problem. And that it has happend before on modular family engines. Anyone have any other inputs?

 

I've noticed it happening quite a bit on the Crown Vic Police Cars I drive, they use the old 2 valve 4.6L. We have the oil changed a Valvoline Express, and I'm sure they use the cheapest filters they can find because like 4 out of 7 cars do it after sitting for just 1-2 hours.

I think it might be a bad oil filter. You said it started shortly after the oil change, so you could always try and change just the filter yourself for about $3 and see if that helps.