Slapping noise on start up - intermittent
 

I noticed my engine will make a "slapping" sort of noise when I start it up sometimes. Its not every time I start the car but frequently enough for me to notice and catch onto it. Does anyone know what this noise might be?

Noise starts at 0:11 and ends at 0:14

MAybe oil pump related. Maybe it takes a few seconds to get everything lubricated.

I know the ls1 based truck motors did something similar. It did it on mine but not nearly as loud. It would do it at least until reached operating temp.

What oil do you run?

Castrol GTX 5W-30 with a Fram Tough Guard filter. I was told on another forum the Fram is a really bad filter to run with the 4V. Also, I was told by the previous owner to not run synthetic till it hit 50k miles (currently at a little over 48k) since the engine was rebuilt not long ago (mileage-wise - year-wise it was 2008).

I have heard bad things about Fram and their anti-flow back valves on the filters. I had a similar sound on my Jeep Wrangler when I ran a Fram once... switched back to the Mopar one and the noise went away.

Really? That's what the other person said. Seems like its the first step I need to take. Is it likely that something is damaged or am I probably okay? It hasn't been happening for too long.

The whole mileage thing is BS. You can use synthetic whenever. Switch to a Wix or OE Ford filter see if it helps.

I have never heard anyone say they had damage from this, but it probably isn't "good" for the engine.

I would think it is just a cheap first step to troubleshoot. Quart or two of oil and a new filter is less than 30 bucks.

For some reason I seem to think there might be a TSB for this...take it to your dealer and have them look at it.

Oh this car has absolutely zero factory parts on it. In fact the only factory parts are probably the block and the shaker.

Gotcha

I'd throw some motor honey in the oil and sell it... OK it might not be that bad.. you are thinking its rod knock and you want us to give another answer.. it could .. might maybe be piston slap.. it might have been there since you bought it?? In which case.. allllll ls motors do it, Mercedes do it and some new 5.0 do it.. just keep track of it and see if it gets worse